# 2203 extra gain stage mod



## jd267

do any of you guys have a simple layout of adding an extra gain stage with fourth pre amp tube two a 2203 HW? I here there is a few ways of doing it,in front end , after v1 etc. I also was to,e it offers 40% more gain.


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## mickeydg5

All you have to do is look at the amplifiers in your signature.

But if you have those why do you need another to modify to do the same?


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## jd267

mickeydg5 said:


> All you have to do is look at the amplifier s in your signature.
> 
> But if you have those why do you need another to modify to do the same?



Lol. That's funny . My HW build is a lot easier to work on and understand. I want my build to be high gain that's all. I'm a metal player man


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## jd267

I'm sure John I has added a fourth pre to one of his builds . I came across some layouts from google but seem they have other things going on . 

One had the tube wired to the high input I think so low input would be stock still. I don't use low input ever but seemed like a quick way of adding the tube.


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## mickeydg5

I get that.

All you have to do is look at the amplifiers you have and decide what you like best in those and experiment from there. They have the extra gain stages.


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## jd267

mickeydg5 said:


> I get that.
> 
> All you have to do is look at the amplifiers you have and decide what you like best in those and experiment from there. They have the extra gain stages.



I want to see what works best in a 2203 not a deizel Herbert


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## jd267

I'm thinking if I add the extra pre and boost the amp also it will be really tight and high gain.. Yummy


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## jd267

If anyone has gone down this road and has a layout that can be posted up would be awesome! Thx


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## jd267

Does the forth tube just tap into v1?


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## john l

Added stages are fun. The way I've decided I like best in an 800 ditches the cathode follower and turns it into a gain stage so there's no added tube but it's more work than I care to type someone through lol. Sorry JD. The info is out there man, some ways sound like complete **** and others are great. This is the fun part where you get to learn what you like and don't like by trying things.


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## ampmadscientist

jd267 said:


> do any of you guys have a simple layout of adding an extra gain stage with fourth pre amp tube two a 2203 HW? I here there is a few ways of doing it,in front end , after v1 etc. I also was to,e it offers 40% more gain.



It's a lot more difficult to make it work right, than you realize.
When you add gain stages, you also add and amplify (a lot of) noise.
The circuit becomes prone to oscillation and ringing microphonics.

It would be easier to buy a Bogner. Which is: basically a 2203 with two more gain stages added.

In other words, there is no simple way to do it. Most people who try this end up with a big mess.


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## charveldan

I think the real question is how to turn your amp into a fridge full of beer ...


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## bulldozer1984

ampmadscientist said:


> It's a lot more difficult to make it work right, than you realize.
> When you add gain stages, you also add and amplify (a lot of) noise.
> The circuit becomes prone to oscillation and ringing microphonics.
> 
> It would be easier to buy a Bogner. Which is: basically a 2203 with two more gain stages added.
> 
> In other words, there is no simple way to do it. Most people who try this end up with a big mess.



Once again, you're wrong. When I started modding my 2204 I had no experience and yet I had workable sounds whilst being quiet enough in no time at all. 

@JD, with my Ceriatone 2204 I added another tube between V1 and V2 and just used 1 half of the triode. 

You really need to understand how a tube stage works before you start. Because, you need to know how to configure the circuit, where you are going to mount the new components and also how you are going to get the power supply to the new tube. 

I fudged around with the stock circuit as much as I could to get an understanding of how it all works. 

For instance, you can get a ****load more gain from a stock 2203 by removing the V1b 10k cathode resistor and putting a 2k7 resistor and 0.68uf capacitor in parallel in its place. But, it won't sound good. It will sound muddy on the bottom, and overly bright on top. 

So you need to understand what all the components do in the circuit so you can tune it. 

So from there you could drop the V1a coupling cap from 0.022uf to 0.0022uf to help tighten up the bottom and then either remove the bright cap or play around with some plate bypass caps to help the top end. And then there is always mucking around with the voltage divider/treble peaker. 

See what I am getting at here ? Once you add another gain stage you then add another set of components to play with. For example:- Plate resistors/capacitors, cathode resistors/capacitors, voltage dividers/treble peakers just to name a few. 

I am not saying that you shouldn't start playing around (it is loads of fun) but I am saying you should keep it simple to start off with.


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## charveldan

I have a 2203 with extra 12AX7 and i'll tell you how to do it for ....


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## flyingskull

Another idea to consider.

Check out 
sloclone forums
Ampgarage
metroamp.com

There is tons of info out there


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## charveldan

Mr numbskull i know u think ur very clever and my biggest fan but dont flatter urself i bant you 2 years ago.

Its not about you.


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## neikeel

charveldan said:


> Mr numbskull i know u think ur very clever and my biggest fan but dont flatter urself i bant you 2 years ago.
> 
> Its not about you.



Eh??


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## RickyLee

As the guys stated, there are many different combinations of things you can do regarding that extra gain stage. Look at all the different schematics you can find to get an understanding (and some ideas to try as well). As the gain stage/tube/triode itself is giving you the gain, then there is the attenuation and tone shaping that goes along with it. There are many things that can be done here which is way too much to go into for typing out much less even trying to explain band pass or high pass or low pass or theory in general. I barely have a grasp on filter networks myself. This will show how complicated it could really be if you wanted it be 

Introduction to Filters

Your interstage attenuation can be real simple and get the job done with just a simple voltage divider or add in a treble peaker or an extra grid resistor or grid load resistor. Part of the fun of it is experimenting with it to see if you can come up with your own recipe. But in reality it probably has been done close somewhere in time.

You might start off with just a simple voltage divider of 470K/470K following your gain stage with the usual Marshall type specs of 100K plate 2k7 cathode and hear MagiK right off the bat. Or it might sound like oscilating out of control farting.


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## jd267

That's what I was thinking Rick. Why not just use what Marshall/Ceriatone used for components ? To tune the extra gain stage . 

I know nothing about this and figuring things out as I go . Sorry for all the questions for the guys that are nolagable and been helping me along the way. Much appreciated. Adding an extra gain stage will push me in the direction I want to be in I would think.


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## RickyLee

For Metal, you might find a pedal up front might be one of the best things you can do. A pedal with mid and upper mid emphasis. And that is whether you add a gain stage or decide not to.


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## jd267

RickyLee said:


> For Metal, you might find a pedal up front might be one of the best things you can do. A pedal with mid and upper mid emphasis. And that is whether you add a gain stage or decide not to.



I always have a OD up front as clean boost my friend  To me 2203's sound like a sloppy mess with out a boost . Gross


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## jd267

Anyone else got any info on an extra gain stage ? Don't want it switchable either


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## jd267

What do you guys think of this?


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## jd267

What I came up with . Two 100k in the V, 68k to B+, 4k7 with .68.

Am I thinking right or am I crazy ? Haaa. Just kind of copied the 2203 give or take.


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## jd267

bulldozer1984 said:


> Once again, you're wrong. When I started modding my 2204 I had no experience and yet I had workable sounds whilst being quiet enough in no time at all.
> 
> @JD, with my Ceriatone 2204 I added another tube between V1 and V2 and just used 1 half of the triode.
> 
> You really need to understand how a tube stage works before you start. Because, you need to know how to configure the circuit, where you are going to mount the new components and also how you are going to get the power supply to the new tube.
> 
> I fudged around with the stock circuit as much as I could to get an understanding of how it all works.
> 
> For instance, you can get a ****load more gain from a stock 2203 by removing the V1b 10k cathode resistor and putting a 2k7 resistor and 0.68uf capacitor in parallel in its place. But, it won't sound good. It will sound muddy on the bottom, and overly bright on top.
> 
> So you need to understand what all the components do in the circuit so you can tune it.
> 
> So from there you could drop the V1a coupling cap from 0.022uf to 0.0022uf to help tighten up the bottom and then either remove the bright cap or play around with some plate bypass caps to help the top end. And then there is always mucking around with the voltage divider/treble peaker.
> 
> See what I am getting at here ? Once you add another gain stage you then add another set of components to play with. For example:- Plate resistors/capacitors, cathode resistors/capacitors, voltage dividers/treble peakers just to name a few.
> 
> I am not saying that you shouldn't start playing around (it is loads of fun) but I am saying you should keep it simple to start off with.




This is what I'm finding out as I go man . Thanks for the tips. Do you have any clips of your build ?


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## jd267

Seems that set up I posted from metro is a john wilder set up. Wonder if he ever started selling those.


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## jd267

This looks interesting wonder what it sounds like. Looks like a good platform to start with


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## ampmadscientist

Using those diagrams, you are going to have problems.

Not that you should be discouraged to experiment...it takes a lot of experience to make it work right.

It's not "just" hooking up the wires. Anybody could do that.
You gotta learn what causes the noise, and learn how to get the noise out.
It's complicated and time consuming. It takes mega patience...
If you don't have test equipment, that makes it much harder.

There are lots of guys who "modify" amps...making it useable is another thing entirely.
There are very few guys who know how to make it work right, that's the experience part.


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## ampmadscientist

bulldozer1984 said:


> Once again, you're wrong. When I started modding my 2204 I had no experience and yet I had workable sounds whilst being quiet enough in no time at all.
> 
> @JD, with my Ceriatone 2204 I added another tube between V1 and V2 and just used 1 half of the triode.
> 
> You really need to understand how a tube stage works before you start. Because, you need to know how to configure the circuit, where you are going to mount the new components and also how you are going to get the power supply to the new tube.
> 
> I fudged around with the stock circuit as much as I could to get an understanding of how it all works.
> 
> For instance, you can get a ****load more gain from a stock 2203 by removing the V1b 10k cathode resistor and putting a 2k7 resistor and 0.68uf capacitor in parallel in its place. But, it won't sound good. It will sound muddy on the bottom, and overly bright on top.
> 
> So you need to understand what all the components do in the circuit so you can tune it.
> 
> So from there you could drop the V1a coupling cap from 0.022uf to 0.0022uf to help tighten up the bottom and then either remove the bright cap or play around with some plate bypass caps to help the top end. And then there is always mucking around with the voltage divider/treble peaker.
> 
> See what I am getting at here ? Once you add another gain stage you then add another set of components to play with. For example:- Plate resistors/capacitors, cathode resistors/capacitors, voltage dividers/treble peakers just to name a few.
> 
> I am not saying that you shouldn't start playing around (it is loads of fun) but I am saying you should keep it simple to start off with.



*"Once again, you're wrong. When I started modding my 2204 I had no experience and yet I had workable sounds whilst being quiet enough in no time at all. "
*
I was modding amps before you wore diapers.
The preacher is preaching to the choir.
http://www.urbandictionary.com/define.php?term=preaching+to+the+choir


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## bulldozer1984

jd267 said:


> This is what I'm finding out as I go man . Thanks for the tips. Do you have any clips of your build ?



Mine has changed a little since this clip. It has less top end and thicker lower mids now. In this clip I was going for an Appetite For Destruction knock off. 
MP3 Player SoundClick

And here is the circuit. 
http://www.marshallforum.com/cellar...ing-my-afd-slash-tone-inside.html#post1236592

Unlike AmpMadFuckwit I actually try to give useful information and not just say "that won't work"


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## tschrama

You can go a long way with a simple multimeter and a soldering iron. Go for it 

Here's one of my first mods, it's the Roccaforte HG100 first gain stage:

100K anode (try out a 470p tot 2n2 cap from anode to cathode to reduce hiss)
10K cathode
100nF cathode bypass cap
22nF coupling cap
68K to 680K voltage divider to grid

-You might want to remove the 470p and/or 1nF bright caps around the sock gain pot, and/or the 470pF bright cap before the last stage.


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## hopkinwfg

wow great information here ! thats what i would also like to know how to learn how to add nice gain and how to we mod to different types of gain structures...


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## bulldozer1984

tschrama said:


> You can go a long way with a simple multimeter and a soldering iron. Go for it
> 
> Here's one of my first mods, it's the Roccaforte HG100 first gain stage:
> 
> 100K anode (try out a 470p tot 2n2 cap from anode to cathode to reduce hiss)
> 10K cathode
> 100nF cathode bypass cap
> 22nF coupling cap
> 68K to 680K voltage divider to grid
> 
> -You might want to remove the 470p and/or 1nF bright caps around the sock gain pot, and/or the 470pF bright cap before the last stage.



That is going to severely weaken the sound unless you alter the 2nd stage or add another stage. Doing that mod to a stock 2203 will actually reduce overdrive.


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## tschrama

jd267 said:


> What I came up with . Two 100k in the V, 68k to B+, 4k7 with .68.
> 
> Am I thinking right or am I crazy ? Haaa. Just kind of copied the 2203 give or take.



I didn't see this before. That'll work, but you have a real risk of HF oscillation. the whole amp has now enormours HF gain. Put a 470pF across the 68K anode resistor if you have any HF oscillation problems.

For the layout I would do it slightly different. I'll attach my version. Look around for Roccaforte gutshots. They are a great example for laying out a high gain amp.


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## tschrama

bulldozer1984 said:


> That is going to severely weaken the sound unless you alter the 2nd stage or add another stage. Doing that mod to a stock 2203 will actually reduce overdrive.



What makes you think that? It's a great high gain marshall mod that I have build lot's of times. Not my design btw, not taking any credits for it.


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## bulldozer1984

tschrama said:


> What makes you think that? It's a great high gain marshall mod that I have build lot's of times. Not my design btw, not taking any credits for it.



Unless I am not reading this correctly

100K anode - SAME AS STOCK
10K cathode - MUCH LESS GAIN THAN STOCK
100nF cathode bypass cap - ONLY BOOSTING HIGH END 
22nF coupling cap - SAME AS STOCK
68K to 680K voltage divider to grid - IS THIS 680k to ground and then 68k grid stopper ?


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## tschrama

bulldozer1984 said:


> Unless I am not reading this correctly
> 
> 100K anode - SAME AS STOCK
> 10K cathode - MUCH LESS GAIN THAN STOCK
> 100nF cathode bypass cap - ONLY BOOSTING HIGH END
> 22nF coupling cap - SAME AS STOCK
> 68K to 680K voltage divider to grid - IS THIS 680k to ground and then 68k grid stopper ?



I meant, 68k to 680K to GND, grid from the 68k-680K node. 

Besides that, you're all correct. But this is an extra stage. We were talking here in this thread about an additional boost stage, right? Sorry if I made you think otherwise.

You're analysis is also correct. Bass is boosted by 17dB, treble beyond 1KHz is boosted by 31dB. You can accomplish about the same with an Boss GE-7 setting the overall volume to +15dB, the bass sliders to +2dB and the treble sliders (> 1KHz) to +15dB.

That GE-7 trick is a great way to try out different kinds of boosts-specs. This one above is great for that very high gain modded Marshall sound, like an AFD100.


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## jd267

bulldozer1984 said:


> Mine has changed a little since this clip. It has less top end and thicker lower mids now. In this clip I was going for an Appetite For Destruction knock off.
> MP3 Player SoundClick
> 
> And here is the circuit.
> http://www.marshallforum.com/cellar...ing-my-afd-slash-tone-inside.html#post1236592
> 
> Unlike AmpMadFuckwit I actually try to give useful information and not just say "that won't work"



Cool man.. I want the half triode in front of V1 as a boost . I started making the components board for the stage . Should be fun


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## jd267

tschrama said:


> I didn't see this before. That'll work, but you have a real risk of HF oscillation. the whole amp has now enormours HF gain. Put a 470pF across the 68K anode resistor if you have any HF oscillation problems.
> 
> For the layout I would do it slightly different. I'll attach my version. Look around for Roccaforte gutshots. They are a great example for laying out a high gain amp.



Took your advice man and changed a few things around . The stage with be installed before V1 as a boost . Half triode . Here is what I got so far


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## jd267




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## charveldan

Lets hear a clip of how it sounds ....


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## jd267

charveldan said:


> Lets hear a clip of how it sounds ....



Got to finish it up first then I will for sure dude. Went on the Polaris razor with the fellas riding today . Prob will have it up and running tomorrow


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## charveldan

With my amp in the extra 12AX7 mode i usually run the "pre" about 6 and hit it with a cleen boost [volume up, gain down] and it sounds over the top.


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## jd267

Well it's wired up and installed just not hearing much difference lol. Something must not be right


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## mickeydg5

JD267
I received your pm.

Do you see that 22nF coupling capacitor (your C1) on that little board for the added gain stage.
The 22nf should connect from Anode to Next Stage Grid.




So move the 22nF connection from that side you have now to the other side of that same 100k resistor (your R2).

You stated that you already have a 68k grid resistor at the grid of the next stage so then remove one of the installed resistors, either R3 or R2. It is not required and it is in the wrong place anyway.


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## jd267

mickeydg5 said:


> JD267
> I received your pm.
> 
> Do you see that 22nF coupling capacitor (your C1) on that little board for the added gain stage.
> The 22nf should connect from Anode to Next Stage Grid.
> 
> View attachment 22350
> 
> 
> So move the 22nF connection from that side you have now to the other side of that same 100k resistor (your R2).
> 
> You stated that you already have a 68k grid resistor at the grid of the next stage so then remove one of the installed resistors, either R3 or R2. It is not required and it is in the wrong place anyway.




I see you made a correction thx. Just tried again . When hooking up to v1 grid it lets out a crazy hum. Still missing somthing. Hmmm


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## mickeydg5

I revised the JPG again.

Did you try the plate resistor bypass capacitor as mentioned? (like the 470pF mentioned)

I cannot see the added to well. Can you give a few good pictures from different angles?

Keep all other wires away from filament/heater wiring.


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## jd267

mickeydg5 said:


> I revised the JPG again.
> 
> Did you try the plate resistor bypass capacitor as mentioned? (like the 470pF mentioned)
> 
> I cannot see the added to well. Can you give a few good pictures from different angles?
> 
> Keep all other wires away from filament/heater wiring.



Just can't hook to the next number one grid. Let's out a crazy hum and cancels out the guitar . I have not tried the cap yet mick


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## jd267




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## mickeydg5

We still need better pictures, better lighting.

I do not see a wire connected to the grid control pin #7.
I do not see a ground wire connected to that ground bus at the top of the small board.
I cannot make out all of the heater wiring.

I see the green wire to plate pin #6.
I see the grey wire to cathode pin #8.
I see a blue wire (from where?) at heater pin #9.

We need more input.


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## jd267

The blue wire in my jumper is the wire that goes to next grid.


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## jd267

The ground wire is grounded to chassis ground


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## mickeydg5

jd267 said:


> The blue wire in my jumper is the wire that goes to next grid.


Not that blue wire. The other blue wire.




jd267 said:


> The ground wire is grounded to chassis ground


I think I can see a black wire at the left of the board to the upper ground bus. But it is hard to make out with the lighting.


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## jd267




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## jd267

mickeydg5 said:


> Not that blue wire. The other blue wire.
> 
> 
> 
> I think I can see a black wire at the left of the board to the upper ground bus. But it is hard to make out with the lighting.



Heater wires


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## jd267

I'll clean up the wiring when I get the stage working .


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## mickeydg5

The alligator clamps, extra wiring running around and flying heater wires will produce noise. So you will hear hum and noise as is at this point.

There still is no connection to added gain stage control grid pin #7. That is the input to the added gain stage. No input = no signal amplification = no gain.


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## jd267

mickeydg5 said:


> The alligator clamps, extra wiring running around and flying heater wires will produce noise. So you will hear hum and noise as is at this point.
> 
> There still is no connection to added gain stage control grid pin #7. No input = no signal amplification = no gain.



Yes that's what on my jumper . When it's hooked up it lets out a crazy loud hum and can't hear the guitar clearly . Trying to figure out why before I solder it down


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## mickeydg5

jd267 said:


> Yes that's what on my jumper . When it's hooked up it lets out a crazy loud hum and can't hear the guitar clearly . Trying to figure out why before I solder it down


From what I can see the blue wire on the alligator clamp is connected to the added gain stage's output at the junction of the 100k and 22nF which goes to the next gain stage grid circuit.


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## jd267

mickeydg5 said:


> From what I can see the blue wire on the alligator clamp is connected to the added gain stage's output at the junction of the 100k and 22nF which goes to the next gain stage grid circuit.



That's exactly right mick. But when it's hooked to next stage grid 1 it turns to a mess


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## jd267

Just soldered it down to see if the jumper was the cause . Amps not even playable with it hooked up.


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## mickeydg5

Still you have no connection to grid pin #7. Where is the input from the jack?
I though that was supposed to connect to the added gain stage which was mentioned to be first in line. Correct?

You are going to get a sh|t load of hum and noise with that alligator jumper and all that other stuff in there especially since going towards higher gain setup. That can also introduce oscillation.

Clean it up and connect everything. Double check your lead dress, connections, signal and power paths.
Then take some more good pictures and show us what you have. Ask questions if needed. We will ask questions if needed to make sure everything is routed and connected properly.

Afterwards then sound can be tested and discussed.


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## jd267

mickeydg5 said:


> Still you have no connection to grid pin #7. Where is the input from the jack?
> I though that was supposed to connect to the added gain stage which was mentioned to be first in line. Correct?
> 
> You are going to get a sh|t load of hum and noise with that alligator jumper and all that other stuff in there especially since going towards higher gain setup. That can also introduce oscillation.
> 
> Clean it up and connect everything. Double check your lead dress, connections, signal and power paths.
> Then take some more good pictures and show us what you have. Ask questions if needed. We will ask questions if needed to make sure everything is routed and connected properly.
> 
> Afterwards then sound can be tested and discussed.



**** do you mean a wire from pin 7 of the new stage to the next pin 7 on v1 grid? They tie pin 7 to pin 7?


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## jd267

I will clean it up a bit but I do t think that's the issue. The heater wires are not touching any other wires . Maybe the component choices are not correct .


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## jd267

The input from the jack is a shielded wire that is under the board to v1 68k grid resistor. Something else is wrong .


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## mickeydg5

jd267 said:


> What do you guys think of this?


This is basically what you are doing. I feel your signal routing is wrong but cannot see everything.

Your R2 is 4.7k, R3 is 68k and R4 is 100k. (The R3 68k is your existing grid stopper at the next stage control grid.

Your INPUT jack should be routed as this one, shown as green wire, but would still use a 68k grid stopper connected at pin #7.


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## tschrama

Maybe this helps: the boost stage schemo. I only work with schemo's never use layout. Atleast then you know what you are doing. Again with your own values; these should work fine but the added 470p cap is recommended.

PS
Needless to say you need a shielded wire to the boost-stage grid, ground the shield at the input jack, use a 33k (or 68K) grid resistor, soldered at the tube socket.


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## jd267

Took the day off today I don't work on boats in the rain . Ripped everything out and starting over . Going to copy my original layout I found that was just posted and go from there . Tired of chasing my tail but it's my own fault lol. Got to learn some how . Mick how about I buy you a plane ticket so you can come help


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## jd267

mickeydg5 said:


> This is basically what you are doing. I feel your signal routing is wrong but cannot see everything.
> 
> Your R2 is 4.7k, R3 is 68k and R4 is 100k. (The R3 68k is your existing grid stopper at the next stage control grid.
> 
> Your INPUT jack should be routed as this one, shown as green wire, but would still use a 68k grid stopper connected at pin #7.



Ok routed all wires with shielded wire in needed spots . Still same problem . I don't get it


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## jd267

The input from jack to pin 2 of v1 is going to volume pot , shield to ground. Should I do the same to gain stage I'm trying to get working?


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## jd267

Should prob just rip it all out lol. Don't have anyone local that could take a look at it . I wired everything like that layout and still nothing . If anyone wants to make a few bucks make me a layout that works around the Ceriatone 2203 layout and email it to me . If it works I'll send you $20 PayPal


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## mickeydg5

It would be best for you to take your layout and schematic with all additions and modifications marked and drawn on it. Then post them in this thread.


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## jd267

Ceriatone Amplification


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## jd267

The amp has No mods done that would interfere with gain stages or inputs


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## mickeydg5

Ok, so your amplifier basically follows the Ceriatone 2203 layout and JCM800 2203 schematic.
Is it your intention to have more gain via the added gain stage during use of both HIGH and LOW inputs? Correct?


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## jd267

mickeydg5 said:


> Ok, so your amplifier basically follows the Ceriatone 2203 layout and JCM800 2203 schematic.
> Is it your intention to have more gain via the added gain stage during use of both HIGH and LOW inputs? Correct?



It really does not matter to me mick I don't use low input so . What ever is easier


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## jd267

The only new thing I did was replace the stock pilot light with a jewel style light to v1 filaments. Two wires .


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## mickeydg5

As long as the indicator bulb is for 6.3VAC use that is fine. Make sure it does not pass close to signal wire and is twisted as the rest of the filament wiring.

It is not a matter of ease but rather intent of the use of the added gain.
I would rather leave the INPUTs intact and place the gain stage after V1 output and before V2 grid circuit.

I can modify a layout and schematic for your reference with your last described gain stage addition.
Give me a while and I will post attachments when done.


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## jd267

mickeydg5 said:


> As long as the indicator bulb is for 6.3VAC use that is fine. Make sure it does not pass close to signal wire and is twisted as the rest of the filament wiring.
> 
> It is not a matter of ease but rather intent of the use of the added gain.
> I would rather leave the INPUTs intact and place the gain stage after V1 output and before V2 grid circuit.
> 
> I can modify a layout and schematic for your reference with your last described gain stage addition.
> Give me a while and I will post attachments when done.



Would be cool of you mick I'll send you somthing for your time


----------



## jd267

Only other mods are depth mod and sat switch with diode on one side and led on the other . As we spoke of before in another thread .


----------



## bulldozer1984

This is why I said you should learn how the stock circuit works before trying to add more. You are trying to climb even though you can walk. I'm not trying to be an asshole it's just the way things are.


----------



## jd267

bulldozer1984 said:


> This is why I said you should learn how the stock circuit works before trying to add more. You are trying to climb even though you can walk. I'm not trying to be an asshole it's just the way things are.



I here you on that man but it's already 70% done so why stop now . I for sure need to learn about the circuit. Hopefully Mickey can help me out with this one.


I need some books or something. I just can't look at the amp and teach myself


----------



## hopkinwfg

damn reading this post makes me wanna diy a marshall 2204 ! but whats the diff between the metro design 2203 to the ceriatone 2203 ? i guess the basic block line up on the preamp circuit is the same huh ? 

am trying to understand how such circuit works like how each tube does in connected to the circuit and how each controls were being tied up to different values of components and block in the circuit....

is there some basic relation on whats going on inside the circuit lets say a metro 2204 to a SLO clone 50 watt ? am currently building the SLO blindly my just following simple instruction from the pics i found...


----------



## jd267

Building amps from a layout is easy to me after all I'm a mechanic . Now understanding what each component is doing etc is another story lol


----------



## mickeydg5

Here you go. None of this is set in stone and is somewhat in accordance to what has been or is being done to this amplifier. Values can be altered.

I tried attaching this way. If you cannot open and copy let me know.


----------



## hopkinwfg

mickeydg5 said:


> Here you go. None of this is set in stone and is somewhat in accordance to what has been or is being done to this amplifier. Values can be altered.
> 
> I tried attaching this way. If you cannot open and copy let me know.
> 
> View attachment 22385
> View attachment 22383


 
great information here Mick... well just curious to know if the Metro 2203 added gain stage done by Metro amp the same circuit as this add on?


----------



## mickeydg5

hopkinwfg said:


> great information here Mick... well just curious to know if the Metro 2203 added gain stage done by Metro amp the same circuit as this add on?


Where is the Metro 2203 added gain stage layout or schematic referenced?
I did not locate one (@ Metro).


----------



## jd267

Wow that is awesome Mickey! Unreal man . I'll try it later and get right back to you. I have to go pull an engine out of a boat quick


----------



## neikeel

mickeydg5 said:


> It is not a matter of ease but rather intent of the use of the added gain.
> I would rather leave the INPUTs intact and place the gain stage after V1 output and before V2 grid circuit.


 
What he says!

I think we suggested this at the beginning.

If you are feeling brave try this:


----------



## jd267

neikeel said:


> What he says!
> 
> I think we suggested this at the beginning.
> 
> If you are feeling brave try this:



I'm all set with that lol. Micks way or the high way


----------



## jd267

Well Mickey seems to have it working but new problem is the pre amp gain pot really has no effect on the amp lol. When all the way off it just squeals.


----------



## jd267

Mickey do those grounds on the shields have to go to the pre amp tubes? Why not to just ground if I may ask?


----------



## jd267

Can't turn the amp up either with out things going haywire . Can't run the gain and volume on low either just squeals


----------



## jd267

The the pre amp volume is off and master is up a little you can still here the guitar . Sounds like a ground problem


----------



## jd267

Moved the grounds from pre amp tubes to chassis ground and seemed to help. Need to sort out that problem with prea amp pot bleed threw . The amp is ripping though Mickey sound like an OD in front lol . For sure what I was looking for man


----------



## mickeydg5

I was 100% sure this kind of stuff was going to happen.   



mickeydg5 said:


> Here you go. None of this is set in stone and is somewhat in accordance to what has been or is being done to this amplifier. Values can be altered.





jd267 said:


> I'm all set with that lol. Micks way or the high way


I wrote that first. then you wrote the other.

It is not my way. All the layout and schematic show is a 2203 with an added gain stage according to the components you had picked.

The layout and schematic depict added components and hookup as required for the modification. The values chosen and the implementation will determine how it reacts. Other stock values may need tweaking to make things work together. The physical layout, component placement and wire dressing may cause odd behavior, noise and oscillation. I am going to say just from watching added gain stage and one wire modifications on these forums that it seems at least 7 or 8 out of 10 projects end up with oddities and problems. Not to discourage anyone.



jd267 said:


> Well Mickey seems to have it working but new problem is the pre amp gain pot really has no effect on the amp lol. When all the way off it just squeals.


The GAIN/Preamp Volume control works or should work like any other 2203. Your added gain stage should add only a limited amount of gain/volume to the amplifier if everything is technically sound.



jd267 said:


> Mickey do those grounds on the shields have to go to the pre amp tubes? Why not to just ground if I may ask?


As noted on the layout the wire shields can be connected to the preamp tube socket bolt/screw at the chassis mounting. I would prefer that.



jd267 said:


> Can't turn the amp up either with out things going haywire . Can't run the gain and volume on low either just squeals





jd267 said:


> The pre amp volume is off and master is up a little you can still here the guitar . Sounds like a ground problem


You need to double and triple check all soldering, connections, wire hookup and wire dress.
The inexperienced are bound to have these problems. I hated to say that but felt it should be said for everyone.

If you have a low signal level or always too clean sound problem then the signal may be being killed off to much at the new added gain stage. The stage has a lower than average output and you chose a 68k (plate) and 100k loading scheme which knocks the signal down quite a bit prior to V2. That may not be the best situation and increasing the values will help, especially increasing the 100k prior to V2 control grid.


Now are you just going through the motions or are you soaking this stuff in and learning something? 


One last thing. All we have to look at is the text in the post and attached files. There is no way for anyone here on this forum to know exactly what has been done in your amplifier.


----------



## jd267

I'm definitely learning a lot Mickey I would have never figured this out . Seems to be working fine only issue is with volume off on pre amp gain you can still here the guitar in a crackly way. I did not choose these values these are on that layout . You think the 100k and 65k are the issue ? Thanks a lot


----------



## jd267

I'm probably have not should have gone down this road lol. But I like to experiment and try to make things better . Does not always work out for me haaa


----------



## jd267

Bypassing cathode resistors did not do it for me but I'm sure there is more to it then I'm aware of . The forth gain stage sounds great but I don't understand enough about the amp to continue . Are there any books on 2203 curcuits fellas? I'm a really fast learner . After all I did build the amp with know experience.


----------



## mickeydg5

jd267 said:


> I'm definitely learning a lot Mickey I would have never figured this out . Seems to be working fine only issue is with volume off on pre amp gain you can still here the guitar in a crackly way. I did not choose these values these are on that layout . You think the 100k and 65k are the issue ? Thanks a lot



With the GAIN/PREAMP VOLUME off or at zero there should be no signal going through. You know I thought about that when looking at your pictures but did not show a correction on the drawings. Your picture seem to show the added gain stage connecting to B+ at the junction of the other V1 two stages plate resistors junction and I left it like that. There are two ways to handle that circumstance. One would be to incorporate another B+ resistor and filter capacitor to separate things. But you are running out of real estate and see crowded already. Another option would be to move the added gain stage B+ supply red wire connection to the other side of the B+ 10k and 50uF filter capacitor where V2's B+ supply is obtained. See what that does for the amplifier.


----------



## bulldozer1984

jd267 said:


> Bypassing cathode resistors did not do it for me but I'm sure there is more to it then I'm aware of . The forth gain stage sounds great but I don't understand enough about the amp to continue . Are there any books on 2203 curcuits fellas? I'm a really fast learner . After all I did build the amp with know experience.



You don't need a book on 2203's. You just need a tube amp book. Once you know what the components do you can apply that to any amp. 

[ame=http://www.amazon.com/Guitar-Amplifier-Handbook-Understanding-Amplifiers/dp/087930863X]Guitar Amplifier Handbook - Understanding Tube Amplifiers and Getting Great Sounds (Softcover): Dave Hunter: 9780879308636: Amazon.com: Books[/ame]


----------



## jd267

bulldozer1984 said:


> You don't need a book on 2203's. You just need a tube amp book. Once you know what the components do you can apply that to any amp.
> 
> Guitar Amplifier Handbook - Understanding Tube Amplifiers and Getting Great Sounds (Softcover): Dave Hunter: 9780879308636: Amazon.com: Books



Just bought that book . Thanks dude . I hate not understanding what is going on under the hood of this thing. Like I said building it is the easy part


----------



## bulldozer1984

Dave Hunters book is one of the most renowned books of it type. I have a copy at home too.


----------



## john l

Google Image Result for http://img502.imageshack.us/img502/2714/roccow.jpg

I'm on a tablet so I'm having trouble posting images but heres a gainy 4 stage thingy that doesn't sound bad as drawn. However I think it's much better after some additional refinement.


----------



## jd267

I was happy with mickeys set up as it sounded like a 2203 still. Just has some issues I don't know how to fix . Bleed threw when pre amp volume is off etc . The preamp pot acted very strange also. The amp would not clean up at all


----------



## mickeydg5

JD267
Not to worry. You can always try again later.

I mentioned a solution to signal bleed in post #100.

Every situation like this will most likely need tweaking.
Like the 470k resistor to ground between V1b and added gain stage may need to be reduced; something between 200k to 360k may suit the progression better.
The 680nF on the added gain stage may be too much; 100nF may be optimal.
The 100pF on the added gain stage may be too small; 470pF or even 1400pF may be better options using the least as possible.
The 100k to ground after the added gain stage and before V2 may need to be increased; somewhere between 200k and 330k maybe.

Like I somewhat mentioned above, the builder has to make everything play well together.


----------



## mickeydg5

JD267
Here are some changes and markups if willing to give it a go and continue.


----------



## jd267

So was screwing around with the gain stage again today and added the changed that Mickey recommended. I did not have a 220k resistor but changed the 100k to 120k. I do have 220k in half watt and guess I can use that for now till I can get a 1 watt. Amp still has the same problems . I made a video so you can see Mickey just waiting for it to post . We really need to get this working because I can't go back to the way the amp sounds with out it haaa.


----------



## jd267

http://youtu.be/_heBJDHdw2o


----------



## hopkinwfg

jd267 said:


> http://youtu.be/_heBJDHdw2o



nice tone !! except for the bug and nice playing too !!


----------



## Wiley Coyote

I've read quite a few threads before joining the MF and I have to say (not taking any sides here) that I haven't seen or heard very much in the way of professionalism from AMS. If I were an amp guy in search of a tech, well let's just say AMS would have even more forum time to fiddle fook around with.


----------



## bulldozer1984

jd267 said:


> http://youtu.be/_heBJDHdw2o



that my friend is called high frequency oscillation. Put some 250pf caps over the plate Resistors (parallel) of the first 2-3 stages. It should help. It's not the only solution though 

Awesome tone man


----------



## jd267

bulldozer1984 said:


> that my friend is called high frequency oscillation. Put some 250pf caps over the plate Resistors (parallel) of the first 2-3 stages. It should help. It's not the only solution though
> 
> Awesome tone man



Still getting that bleed threw also with preamp volume and master


----------



## flyingskull

That is awesome tone man, really jealous


----------



## jd267

Help me understand what is what here . The 100nf cap and 4.7k resistor is the cathode resistor bypassed with a cap. What are the other two resistors doing and cap? Also why the resistors on the grids?


----------



## bulldozer1984

jd267 said:


> Help me understand what is what here . The 100nf cap and 4.7k resistor is the cathode resistor bypassed with a cap. What are the other two resistors doing and cap? Also why the resistors on the grids?



I can only assume the resistors and cap you are talking about as I don't know how your circuit is setup at the moment. Can you please point me to the correct layout of your circuit. 

Regarding your grid resistor question. 
Resistors tied directly to the grid help to not overload that tube stage with too much signal. Which is good for eliminating noise and also squeal.


----------



## mickeydg5

jd267 said:


> Still getting that bleed threw also with preamp volume and master


Can you provide a video of the "bleed through" you are experiencing while describing it with settings?

As mentioned, that whistling is high frequency oscillation.
I will put some more on the drawings for you.

The 120k is fine instead of the 220k. Actually it is best to keep them low to tame the preamp. They can be raised to try to get more if needed later.
You do not need 1W resistors in those positions. Half watt resistors are fine.

Some updated drawings. Notice things in red like notes, resistor values and added plate resistor bypass capacitors.


----------



## neikeel

My suggestion is add a cold stage and get it working and then slowly drop the cathode resistor value +/- bypass cap to taste.


----------



## mickeydg5

His stage is fairly cold. We are tweaking the second and third stage to be colder now.

If the oscillation is caused by something other than just a gain issue it may be harder to manage.

Make sure that the current problem is not caused by tube socket contacts or the tubes themselves.
Try cleaning things with an electronic contact cleaner, socket prongs and tube pins. Swap tubes around or even try lower gain tubes to test outcome if possible.

It could be a combination of those things although the gain may hold the higher fault. Things just need to be checked and managed.


----------



## jd267

Well made the changes and they did not effect the squealing when pre amp gain is low. Is it possible that the stage is running to cold? It gets better when pre amp volume is turned up


----------



## jd267

New video 

http://youtu.be/f2HpRt-PzjA


----------



## jd267

Well after messing around may be onto somthing . NOW v3 does not like my 80's square getter 12ax7 . When putting a sovtek lps in its spot noise is gone lol. Moved the square getter to inverter . It's lost the tone I like but that must tell us somthing ? Mickey will you take the floor now


----------



## jd267

mickeydg5 said:


> This is basically what you are doing. I feel your signal routing is wrong but cannot see everything.
> 
> Your R2 is 4.7k, R3 is 68k and R4 is 100k. (The R3 68k is your existing grid stopper at the next stage control grid.
> 
> Your INPUT jack should be routed as this one, shown as green wire, but would still use a 68k grid stopper connected at pin #7.





So Mickey if I dont want the grid resistor on NOW v3 pre amp tube socket where would it go on my fabricated board? There is know room for it in the tube socket area . Need it on the board

By v3 I mean 1- 3 in line .


----------



## jd267

[/QUOTE]


----------



## jd267

Also after reading what this person has stated in his directions 

Says 3 and 4 should Equal 500k. ?


----------



## jd267

jd267 said:


> So Mickey if I dont want the grid resistor on NOW v3 pre amp tube socket where would it go on my fabricated board? There is know room for it in the tube socket area . Need it on the board
> 
> By v3 I mean 1- 3 in line .



I figured this out .. Stepped away for a bit and went back . I also noticed the cap 1000pf paralleled on the 100k of old v1 to pin 6 makes the problem worse . I removed it.


----------



## jd267

I should also add that I played with resistor values and had the amp sounding incredible. Very high gain ! This had no effect of the squeal problem,stayed the same .


----------



## RickyLee

Yeah, you just have to find the values and recipe that will give you the compromise between the awesome tone you want and stability. Sometimes you tinker and find the most incredible high gain tone but the amp will not cooperate when you start turning the volume up to band levels.

My preamp tone somewhat fell together but I got lucky the first time with my values. I still want to go back and tinker a bit later on. But my tone is opposite from yours. Mine is a high gain tone but with more of a Classic 70's - 80's Marshall voicing.


----------



## jd267

I really need to fix this problem . It's driving me crazy. Nik from Ceriatone said its from lead dress. I told him a did not have the problem before adding the gain stage but since it's very high gain it's showing it true colors lol.

So what wires should not be near others? Could someone make me a list of wires to look out for ? I dont know what wires should not be touching others.


----------



## RickyLee

I have a project that has a lot crammed into a smaller chassis. I have wires on top of wires and some crossing as well. My amp is quiet so at this point I am not going to do anything with it unless I rework it then I will try making it look more pleasing to my eyes.

Do you have shielded wire for your input and a few other inputs to gain stages? Using any of the hot shield, input Ground or capacitor shield schemes?


----------



## jd267

I have shielded wire on input to v1, also pre amp volume, volume pot also. Prob missing a few other spots it was used . My layout is posted in this thread.


----------



## jd267

What gets me is why when swapping third pre amp tube from Chinese 12ax7 to sovtek lps the problem is gone. Also so is my high gain lol


----------



## bulldozer1984

Looking at your lastest vid I noticed that extra pot and switches on the front. You said a depth mod. I can only assume that the extra pot controls that, and it controls the low end of your negative feedback loop. If that is the case, you should not have mounted it on the front. You should never put any power amp signal anywhere near the input stage. Because it can cause noise issues.


----------



## jd267

It did not make this noise before the added stage and don't think the depth mod is the problem . Why when I put the lps in v3 the noise goes away? Know one seems to be questioning that . Where is Mickey been he is MIA lol


----------



## bulldozer1984

jd267 said:


> It did not make this noise before the added stage and don't think the depth mod is the problem . Why when I put the lps in v3 the noise goes away? Know one seems to be questioning that . Where is Mickey been he is MIA lol



Man.. You need to listen for a second. You keep saying "I dont think it is that". If you knew what you were doing, this thread wouldn't exist. 

What you dont seem to understand is, you have added another gain stage. That is 4 stages of tube amplification. Amplification makes everything louder.. Guitar signal, and noise ! 

We aren't answering that last bit because nobody has any idea why. To be honest, your build is quite messy, and is not a good foundation for a high gain preamp. I am not saying you cannot get that amp working right, but I am saying you really need to start from scratch. 

Quite a few times, there have been suggestions that you need to clean up your lead dress. You should have listened !

Mickey probably feels he has given you enough of his free time to help you out. He was giving you alot of advice, and some of it you wouldn't take. Would you put alot of time into a mechanic apprentice that wasnt listening to your words of wisdom ? 

I do not mean this post in offence, but I needed to spit it straight.

Maybe this will be the statement that turns it around for you.. When I added my 4th stage, it had alot of HF oscillation as I turned the preamp knob up (although not as bad as yours). After a couple of hours of frigging around, I removed all the components/wires/circuitry from the added stage and one by one put it back together. I put it back together and the HF oscillation was gone ! So obviously there was something that I had done that was inducing noise. To this day I don't know what it was.. 

The difference between my amp and yours is that my amp was built by Ceriatone so it is very neat and tidy. Before I added my extra stage, I spent months learning what the components do and then putting that to practice by messing with the stock circuit. I had a high gain amp without adding extra stages (think Chupacabra or Yeti).


----------



## jd267

What Is messy about my amp? The wiring? I have been listing the whole time dude what do you mean? The amp was quiet as a mouse (with depth pot mod) before adding the stage. I have been doing what Mickey has been saying step by step he is the only one that has been steering me in the right direction . What have you recommended this whole gain stage mod? Thanks for making me look like a jerk dude


----------



## jd267

Just so you know I unhooked the depth mod and wired the NFR direct to 8ohm tap like stock and it made know difference. 

Trust me I'm listing. Remember this is my first build of any kind of amp from scratch . I think I did pretty dame good...


----------



## RickyLee

I had an issue last week with an amp that all of a sudden had bad noise oscillation when I had nothing plugged into it - no guitar plugged into the amp or no cable plugged into the front input. I would plug my guitar into the amp and the noise would go away. I started thinking about what I had last done to it which was replace the shielded cable from input to first gain stage. So before I started removing wires and such I replaced the first 12AX7 and problem was cured. 

Sometimes tubes are part of the noise problems or enhance the noise that is already there. The difference between a Sovtek LPS and Chinese 12AX7 could be drastic in a high gain circuit.

I was curious as to V3, is it the cathode follower circuit? I remember reading that the Sovtek LPS sometimes go bad running in a cathode follower circuit, even more so if the cathode to heater voltage spec is exceeded. Most Marshall cathode followers exceed this rating. So I am wondering if your LPS is a bit on the weak side on its gain compared to the Chinese 12AX7?


----------



## jd267

bulldozer1984 said:


> Man.. You need to listen for a second. You keep saying "I dont think it is that". If you knew what you were doing, this thread wouldn't exist.
> 
> What you dont seem to understand is, you have added another gain stage. That is 4 stages of tube amplification. Amplification makes everything louder.. Guitar signal, and noise !
> 
> We aren't answering that last bit because nobody has any idea why. To be honest, your build is quite messy, and is not a good foundation for a high gain preamp. I am not saying you cannot get that amp working right, but I am saying you really need to start from scratch.
> 
> Quite a few times, there have been suggestions that you need to clean up your lead dress. You should have listened !
> 
> Mickey probably feels he has given you enough of his free time to help you out. He was giving you alot of advice, and some of it you wouldn't take. Would you put alot of time into a mechanic apprentice that wasnt listening to your words of wisdom ?
> 
> I do not mean this post in offence, but I needed to spit it straight.
> 
> Maybe this will be the statement that turns it around for you.. When I added my 4th stage, it had alot of HF oscillation as I turned the preamp knob up (although not as bad as yours). After a couple of hours of frigging around, I removed all the components/wires/circuitry from the added stage and one by one put it back together. I put it back together and the HF oscillation was gone ! So obviously there was something that I had done that was inducing noise. To this day I don't know what it was..
> 
> The difference between my amp and yours is that my amp was built by Ceriatone so it is very neat and tidy. Before I added my extra stage, I spent months learning what the components do and then putting that to practice by messing with the stock circuit. I had a high gain amp without adding extra stages (think Chupacabra or Yeti).




Well I'm man enough to say this and not a petty bitch so here it goes 

After you saying the depth pot to close to input jack could be the problem I went back and looked again . I did unhook it from the NFR and jump the resistor back to 8ohm tap I did not unhook the other end of wire 


I ran a shielded wire to the pot and the problem got better . I then moved the pot from that area and the problem is gone lol. 

So yes I guess I'm an asshole like you said haaaa. Kidding . Cut me some slack this is my first build 


You hit the nail on the head dude . Cuttos


----------



## bulldozer1984

jd267 said:


> Well I'm man enough to say this and not a petty bitch so here it goes
> 
> After you saying the depth pot to close to input jack could be the problem I went back and looked again . I did unhook it from the NFR and jump the resistor back to 8ohm tap I did not unhook the other end of wire
> 
> 
> I ran a shielded wire to the pot and the problem got better . I then moved the pot from that area and the problem is gone lol.
> 
> So yes I guess I'm an asshole like you said haaaa. Kidding . Cut me some slack this is my first build
> 
> 
> You hit the nail on the head dude . Cuttos



You're not an asshole at all. Trust me, we have had those guys on here and you're not one of Em. I was never trying to make you feel bad about the build quality, I think you did a great job considering its your first build. I was just getting at the fact that lead dress etc could cause issues.

Ok, so the squealing has gone ? How about the bleed issue ?


----------



## jd267

bulldozer1984 said:


> You're not an asshole at all. Trust me, we have had those guys on here and you're not one of Em. I was never trying to make you feel bad about the build quality, I think you did a great job considering its your first build. I was just getting at the fact that lead dress etc could cause issues.
> 
> Ok, so the squealing has gone ? How about the bleed issue ?



Gone brotha! Or should I say mate ! Lol


Now let's juice up the gain my Marshall forum friends


----------



## bulldozer1984

Hopefully that depth control is gone forever. I don't see the point of them anyway unless its a production model amp. If you are tweaking the amp yourself, you are tweaking it to you taste. You tweak the entire frequency range to your liking and then you're happy. I tweak it so it sounds awesome with all the tone controls at 12 o'clock so when playing live I have plenty of range to tune it to the room. Well at least that is how I operate. 

So you want to add more gain ?


----------



## jd267

O yes more gain.. The depth pot will be in the back now


----------



## bulldozer1984

jd267 said:


> O yes more gain.. The depth pot will be in the back now



Leave the depth pot out until the end, please. 

Judging by the first vid, the amps tone sounds quite balanced so I don't want to change the voicing too much. 

On the last cathode (V2a), put a 0.68 or 1uF cap in parallel with the 820r resistor.


----------



## jd267

What about the two resistors on my added gain stage R3 and R4 ? I have a 68k and a 100k that's killing gain it seems. Well cutting it back


----------



## bulldozer1984

No leave them alone. They are keeping your amp quiet and tight. Go with my suggestion


----------



## john l

Great job. So I've lost track....How do you have it configured? Micky update the drawing so we can see where he's at.


----------



## jd267

Tried the cap and seemed to put a stank on the amp tone I did not like . I raised the 68k on B+ to 100k. And added the needed gain . 

How can I restore some of the lost low end from the caps on added gain stage?


----------



## bulldozer1984

jd267 said:


> Tried the cap and seemed to put a stank on the amp tone I did not like . I raised the 68k on B+ to 100k. And added the needed gain .
> 
> How can I restore some of the lost low end from the caps on added gain stage?



Oh I thought the 68k was your grid resistor ?? Can you please show us an updated schem ? If we are going to do this we need to do it properly, not guessing.


----------



## jd267

I don't have a schem . The value I went up with is r1 on the above layout.


----------



## jd267

That 22nf on my fabed board is that robbing lows?


----------



## john l

Which drawing though. The last one Micky drew?


----------



## jd267

Yes


----------



## john l

jd267 said:


> Yes



Jd just take 5 minutes to draw your bonus board with the values you used and up load it so we can see.


----------



## jd267

The values are the same as mickeys as of now .


----------



## bulldozer1984

Ok so I have attached the schem.

R1 (plate resistor) = 100k
R2 (cathode resistor) = 4k7
R3 (voltage divider) = 68k 
R4 (stunt resistor) = 100k 
C1 (cathode cap) = 100nF
C2 (coupling cap) = 22nF


----------



## mickeydg5

From post #96



mickeydg5 said:


> I was 100% sure this kind of stuff was going to happen.





mickeydg5 said:


> The physical layout, component placement and wire dressing may cause odd behavior, noise and oscillation. I am going to say just from watching added gain stage and one wire modifications on these forums that it seems at least 7 or 8 out of 10 projects end up with oddities and problems. Not to discourage anyone.
> 
> You need to double and triple check all soldering, connections, wire hookup and wire dress.
> 
> The inexperienced are bound to have these problems. I hated to say that but felt it should be said for everyone.
> 
> One last thing. All we have to look at is the text in the post and attached files. There is no way for anyone here on this forum to know exactly what has been done in your amplifier.




From post #100



mickeydg5 said:


> With the GAIN/PREAMP VOLUME off or at zero there should be no signal going through. You know I thought about that when looking at your pictures but did not show a correction on the drawings. Your picture seem to show the added gain stage connecting to B+ at the junction of the other V1 two stages plate resistors junction and I left it like that. There are two ways to handle that circumstance. One would be to incorporate another B+ resistor and filter capacitor to separate things. But you are running out of real estate and see crowded already. Another option would be to move the added gain stage B+ supply red wire connection to the other side of the B+ 10k and 50uF filter capacitor where V2's B+ supply is obtained. See what that does for the amplifier.




I have been busy with work and then I had to take care of the yard.

I have also done some testing with cascading, oscillation and whistling. Even with 12AY7 and 12AU7 I can get oscillation. So it is not particularly the tube or gain factor though higher gain does bring out the noise and oscillation in spades.

Your Sovtek is either very weak or very unsusceptible to noise/microphonics or both. That can make it seem as if the problem has vanished. But it has not. Or in could have been a socket prong to tube pin contact problem.

Your amplifier has a lot going on and is crowded. This adds problems. Added and extra wiring adds problems. Layouts where circuits an wiring are crisscrossing adds problems. That has everything to do with layout and lead dress as Nik put it and I had mentioned in post #96. Bulldozer also mention placement of controls and wire routing. The added gain brings out the problems big time. That is what most do not understand, meaning the affect it has on showing noise and weaknesses. There are lots of things than can induce or create noise form mediocre solder connections to wire routing as you are finding out and that is going to be picked up and multiplied endlessly with all of the added gain. The filtering will not be able to handle it, more about that coming up.

Like Bulldozer stated, he had the same problem and one fookup killed it. He took it apart and rebuilt it. Then it worked. But he has no idea what caused it. The problem with that is if the same or another problem occurs in the future he is back in the same boat.

Yes the plate resistor bypass capacitor 1000pF was placed there to see if it may help. It did not it made things worse. That can indicate too many stages with too much gain in one spot. As I mentioned in post #96 additional filtering circuits in the B+ rail may be required to separate gain stages.

JD267, you have been implementing suggestions as noted in the post in an effort to rid the problem. It is not my or anyone else's design, layout or routing. Notice it is not that easy. As I mentioned in post #96, there is no way for anyone here to know exactly what has been done in your build. You are making an inexperienced attempt at a higher gain modification on a build but like I mentioned 7 out of 10 crash and burn. But there is no harm in trying.

It seems the DEPTH CONTROL was contributing to noise/oscillation and moving or removing it helped. That is part of layout and lead dress.

You can return some low end by increasing cathode bypass capacitors, adding one to V1b. Decreasing the plate resistor bypass capacitors should help retain more lows and mid frequency.

Another note for anyone with added gain stage modifications is that oscillations are not always heard. As I mentioned doing test comparing stock and then switching to added stage you can witness an unheard as well as a heard oscillation by monitoring the power tube idle current. When oscillation occurs current will increase dramatically, usually doubling or more. That is even when unheard. That can still do damage if becoming a runaway state. Very high frequency oscillation may involve very high AC amplified voltage.


----------



## jd267

Understandable Mickey . Seems to be going well if you ask me . I don't have any weird problems I'm just trying to tune the stage now . 

Would like some more thump as I feel it lost some now . 

Would like to tame some highs also

The amps pre amp pot sounds good at 12oc so I think the amp has plenty of gain I would think.

Would also like to darken the tone a little also.


----------



## jd267

bulldozer1984 said:


> Ok so I have attached the schem. Please confirm.
> 
> R1 (plate resistor) = 100k
> R2 (cathode resistor) = 4k7
> R3 (voltage divider) = 68k
> R4 (stunt resistor) = 100k
> C1 (cathode cap) = ?
> C2 (coupling cap) = ?





Cathode cap 100nf. Coupling cap 22nf


----------



## bulldozer1984

jd267 said:


> Cathode cap 100nf. Coupling cap 22nf



Increasing the value of C1 anywhere up to 1uF will bring in more lower mids for a thicker tone.


----------



## jd267

bulldozer1984 said:


> Increasing the value of C1 anywhere up to 1uF will bring in more lower mids for a thicker tone.



I messed around with that cap last night and things got loose sounding . Maybe this is the end of the road . I'm trying to shape the palm mutes if that make any sense to you.


----------



## jd267

Seems I tamed the highs a bit playing with the voltage dividers . Hey fellas would any of you guys know how to remove my FX loop? The Ceriatone fx loops are a joke anyhow and would like to put my depth pot there and block the other hole.


----------



## john l

jd267 said:


> Seems I tamed the highs a bit playing with the voltage dividers . Hey fellas would any of you guys know how to remove my FX loop? The Ceriatone fx loops are a joke anyhow and would like to put my depth pot there and block the other hole.



It should be a simple matter of removing what's there and running a wire from the center wiper of the master to the PI entrance.

Point G to Point Q on the ceriatone 2203HW layout.


----------



## jd267

I have been looking at that . Wiper to cap it looks like thanks john you guys are the best and this would have not happened with out all your help . Mickey , John I etc . I noticed that there is some squeal when pre amp gain is very low like on one but goes away ones it hits two or three. No squeal at loud volume .


----------



## john l

More than likely you have an oscillation that travels out of the what humans can hear when you turn the pot. 

Post pics of your amp so we can see how everything's wired and we may be able to help you arrange things to help with that. 

Most of he time oscillations can be corrected by better layout but other times you might have to add little suppression circuits to stabilize the problem. 

As far as getting a little more low end back in the picture you might like the old trick of adding a 100k-220k res in between the center wiper of the master and PI entrance. I only bring it up since you'll be there getting rid of the loop any way. 
This forms a low pass filter to help the master sound fuller early on.


----------



## jd267

What's the best way to run the B+ wire to my fabed board ? When I move it around the problem gets better . Away from pre amp tubes? Is there a way to make my (depth) mod more powerful ?


----------



## jd267

john l said:


> More than likely you have an oscillation that travels out of the what humans can hear when you turn the pot.
> 
> Post pics of your amp so we can see how everything's wired and we may be able to help you arrange things to help with that.
> 
> Most of he time oscillations can be corrected by better layout but other times you might have to add little suppression circuits to stabilize the problem.
> 
> As far as getting a little more low end back in the picture you might like the old trick of adding a 100k-220k res in between the center wiper of the master and PI entrance. I only bring it up since you'll be there getting rid of the loop any way.
> This forms a low pass filter to help the master sound fuller early on.



I'll give that a try john !


----------



## jd267

Now I have a hole in the front of the chassis . Dame it lol. Got some plugs on the way or I can order a new faceplate from Nik . Or put some more mods lol


----------



## bulldozer1984

jd267 said:


> I messed around with that cap last night and things got loose sounding . Maybe this is the end of the road . I'm trying to shape the palm mutes if that make any sense to you.



WHen it comes to tweaking, less is more. I hope you tried small increments. 100n, 220n, 330n, 470n, 680n etc. 

Try John suggestion (BTW good one John I am keeping that one in my pocket for another day) and if it doesnt work you can play around with the cap that controls the depth mod.


----------



## jd267

Dozer I ended up using your 1uf on 820ohm . I also moved my slope to 39k and changed voltage dividers to 220k /390k to that new stage . Got rid of some of the highs and thickened up the tone .


----------



## bulldozer1984

jd267 said:


> Dozer I ended up using your 1uf on 820ohm . I also moved my slope to 39k and changed voltage dividers to 220k /390k to that new stage . Got rid of some of the highs and thickened up the tone .



Are you happy with the tone ?


----------



## john l

Since it's brought up. I think the 1meg/.0047 resonance is ridiculous sounding in these amps. 250k/.0033 is much more "real" sound.


----------



## jd267

I have a .0033 on my resonance mod now . Still 1 meg pot though. I also went down to 250pf on the fizz cap . The amp sounds like my old rev blue ubershall when I would boost it now haaaa. This amp is a beast for sure . John when I tried your resistor mod that was from wiper of mast vol to cap where fx loop was right? If so it made the amp sound jingly like . Hard to explain


----------



## jd267

Well here is where I'm at fellas prob not your thing but this is a modern metal 2203 style amp . https://youtu.be/zHAcTspsr5c I was trying all different settings . Just a few slow riffs


----------



## jd267

The next question. Lol. I have el34 power tube , 6550's and kt88's. Should I try them ? Just got to swap a resistor may be worth it


----------



## jd267

I remembered to run 6550/kt88 I would need to lower the 47k bias resistor to bias pot . I deleted my question


----------



## john l

jd267 said:


> I have a .0033 on my resonance mod now . Still 1 meg pot though. I also went down to 250pf on the fizz cap . The amp sounds like my old rev blue ubershall when I would boost it now haaaa. This amp is a beast for sure . John when I tried your resistor mod that was from wiper of mast vol to cap where fx loop was right? If so it made the amp sound jingly like . Hard to explain



250pf on fizz cap??? Do you mean treble cap. The fizz cap is the 47pf in between your phase inverters plate resisters on the board. That is a mod some do but not for what you're trying to do. 

The treble cap is 470-500pf and if you drop it to 250p it's pretty subtle, to me it sounds like there are less high mids in the tone. 

If everything is working correctly elsewhere in the amp the 100k-220k in series with the wire to the .022 entering the PI should do exactly how What I said earlier. You may also notice that the volume isn't completely gone when the pot is turn all the way off but this is normal. This is a popular tweak in a few books out there.


----------



## mickeydg5

john l said:


> More than likely you have an oscillation that travels out of the what humans can hear when you turn the pot.
> 
> Post pics of your amp so we can see how everything's wired and we may be able to help you arrange things to help with that.
> 
> Most of he time oscillations can be corrected by better layout but other times you might have to add little suppression circuits to stabilize the problem.
> 
> As far as getting a little more low end back in the picture you might like the old trick of adding a 100k-220k res in between the center wiper of the master and PI entrance. I only bring it up since you'll be there getting rid of the loop any way.
> This forms a low pass filter to help the master sound fuller early on.





bulldozer1984 said:


> WHen it comes to tweaking, less is more. I hope you tried small increments. 100n, 220n, 330n, 470n, 680n etc.
> 
> Try John suggestion (BTW good one John I am keeping that one in my pocket for another day) and if it doesnt work you can play around with the cap that controls the depth mod.


Yes to all of that.

The 100k prior to the PI is basically like the added grid stoppers. In this case the higher value of 100k will impede more signal but will significantly shelve off more higher frequency than say a 10k or the standard 68k commonly seen.

Remember my note. Just because you cannot hear an oscillation does not mean it is not there or that it cannot be created under certain circumstances.


----------



## bulldozer1984

[ame]http://www.youtube.com/watch?v=zHAcTspsr5c[/ame]
The payoff for me was when you tuned back to standard and played Jake. Sounds mean.. I like less gain personally but it does sound good. Its hard to judge from YT clips but it seems like you achieved your original goal.


----------



## jd267

john l said:


> 250pf on fizz cap??? Do you mean treble cap. The fizz cap is the 47pf in between your phase inverters plate resisters on the board. That is a mod some do but not for what you're trying to do.
> 
> The treble cap is 470-500pf and if you drop it to 250p it's pretty subtle, to me it sounds like there are less high mids in the tone.
> 
> If everything is working correctly elsewhere in the amp the 100k-220k in series with the wire to the .022 entering the PI should do exactly how What I said earlier. You may also notice that the volume isn't completely gone when the pot is turn all the way off but this is normal. This is a popular tweak in a few books out there.




I meant fizz cap. PI resistors cap. I may go back to 120p. I tried the 100k off wiper and did not like what it did but thanks for the suggestion john. How does the high pass tremble peaking cap differ from the tremble cap above it?

The 500pf cap to tremble pot. And the other 500pf that went to the old v2. Why on the yeti Nik removes one of the 470k resistors paired with the cap?


----------



## john l

jd267 said:


> I meant fizz cap. PI resistors cap. I may go back to 120p. I tried the 100k off wiper and did not like what it did but thanks for the suggestion john. How does the high pass tremble peaking cap differ from the tremble cap above it?
> 
> The 500pf cap to tremble pot. And the other 500pf that went to the old v2. Why on the yeti Nik removes one of the 470k resistors paired with the cap?



Hmm I think that you may not be describing what you think your describing jd . 
Bright cap (cap across pre gain)
Treble peakers/voltage dividers (470-500pfs across 470k resistors)
Treble cap (470-500pf in your tone stack goes to your treble pot)
Fizz cap (47pf that bridges the 82k and the 100k phase inverter plates)

The reason you don't see that 470k in the yeti or the chup is because he made it variable, note the second gain control.


----------



## jd267

john l said:


> Hmm I think that you may not be describing what you think your describing jd .
> Bright cap (cap across pre gain)
> Treble peakers/voltage dividers (470-500pfs across 470k resistors)
> Treble cap (470-500pf in your tone stack goes to your treble pot)
> Fizz cap (47pf that bridges the 82k and the 100k phase inverter plates)
> 
> The reason you don't see that 470k in the yeti or the chup is because he made it variable, note the second gain control.



Ahh that explained that. John I changed the fizz cap lol. I just went back to 100pf. I put the 250pf across where the tremble peaker cap is with 470k resistors and it made the amp more dark but to dark . May be on to something there. Maybe a 300pf may do it for me . It seemed to make the tremble pot not so responsive and touchy .


----------



## jd267

The cab thanks bob sourmash!


----------



## mickeydg5

JD267
I listened to your last video. I do not know how it was recorded but it sounded fairly dark on my end. Maybe to dark, unless you had the PRESENCE and TREBLE turned down.


----------



## jd267

mickeydg5 said:


> JD267
> I listened to your last video. I do not know how it was recorded but it sounded fairly dark on my end. Maybe to dark, unless you had the PRESENCE and TREBLE turned down.



It's like ubershall dark lol. Mickey that resistor on our board for gain stage the one with 1400pf on it if I raise that what will that do increase gain? I would like to take a touch of gain away so lower it back to 68k? I have a 100 in there now


----------



## jd267

I put the 47pf back . Did not really notice that much difference. What did help was cutting the tremble peaking cap to 250pf on voltage divider resistors 470/470k.

I'm Just posting what I'm screwing with guys . 

One MAIN Problem is the amp really turns to a hot sloppy mess when the drop c guitar gets plugged in OMG so loose and gross sounding lol. Lowering bass and resonance does not help. 

It may be time for AKA the Mickey Mod. If you feel up to it Mickey could you make one of those nifty layouts for me? With the components off a mini switch ? I know I ask for a lot . Hole is already drilled


----------



## john l

jd267 said:


> It's like ubershall dark lol. Mickey that resistor on our board for gain stage the one with 1400pf on it if I raise that what will that do increase gain? I would like to take a touch of gain away so lower it back to 68k? I have a 100 in there now



That's your plate load and it controls the plate voltage that stage sees. 100k is typical there. Raising it will give you the impression of more gain even though that's not really what is happening. You might like the effect of a smaller value gain pot, lots of high gainers utilize these. Put a 1meg resistor across the gain pot and see if that starts things going in the right direction.


----------



## jd267

john l said:


> That's your plate load and it controls the plate voltage that stage sees. 100k is typical there. Raising it will give you the impression of more gain even though that's not really what is happening. You might like the effect of a smaller value gain pot, lots of high gainers utilize these. Put a 1meg resistor across the gain pot and see if that starts things going in the right direction.



I put the 68k back and seemed to make the amp sound clearer if that makes sense. Across the gain pot like two end lugs?


----------



## john l

jd267 said:


> I put the 68k back and seemed to make the amp sound clearer if that makes sense. Across the gain pot like two end lugs?



Yep across the end lugs. It's kinda like having a 500k pot there but not exactly the same. I like to use all the way Down to 250k gain pots. 

Raising preamp voltages can definitely effect how clear a stage can sound.


----------



## jd267

john l said:


> Yep across the end lugs. It's kinda like having a 500k pot there but not exactly the same. I like to use all the way Down to 250k gain pots.
> 
> Raising preamp voltages can definitely effect how clear a stage can sound.



How would you go by doing that?


----------



## jd267

Really learning a lot guys . You were not kidding about lead dress geezz. So I had a squeal when pre amp volume was under 3 so I started moving around wires and about an hour later I found the problem. My saturation switch mod was causing it . I had to move the cap from it to right above v3 pre amp tube and run a shielded wire to the switch next to the input jack and noise is gone!! . I tryed to put a switch on front with stock slope resistor on one side and 47k on the other and it would not work it made the amp squeal again. Seems anything next to the input jack is an issue. Should I make a box shield for the inputs? I have to try dialing some gain out of the pre amp also I'm going to try john's resistor across the pre amp pot to bring it down to 500k and if it works I'll change the pot that should cut the gain right? The amp mushes out past 12oc lol


----------



## jd267

John I just tried your suggestion on the filter caps . I cut the fist one back to 2.2 and really helped things out. I also removed the 680nf and placed a 470nf there with the 2k7 stock resistor . That's helped also. The 470 is a lot bigger in size than the 680nf cap?


----------



## hopkinwfg

epic !! so everything is on set with the extra 12ax7 stage gain boost huh ? any schemetic thats finalised for sharing ? haha..


----------



## john l

jd267 said:


> Really learning a lot guys . You were not kidding about lead dress geezz. So I had a squeal when pre amp volume was under 3 so I started moving around wires and about an hour later I found the problem. My saturation switch mod was causing it . I had to move the cap from it to right above v3 pre amp tube and run a shielded wire to the switch next to the input jack and noise is gone!! . I tryed to put a switch on front with stock slope resistor on one side and 47k on the other and it would not work it made the amp squeal again. Seems anything next to the input jack is an issue. Should I make a box shield for the inputs? I have to try dialing some gain out of the pre amp also I'm going to try john's resistor across the pre amp pot to bring it down to 500k and if it works I'll change the pot that should cut the gain right? The amp mushes out past 12oc lol



Yep. The circuit is laid out the way it is because that's the way the signal needs to flow, if you start adding mods to parts of the circuit that live down the road IE cathode follower and NFB loop... next to things like the inputs which are just extensions of your grids at the beginning you're going to have problems. 
Add to this that anything happening at the inputs gets re amplified many times over and it makes sense either steer clear of this area for certain mods.


----------



## john l

jd267 said:


> John I just tried your suggestion on the filter caps . I cut the fist one back to 2.2 and really helped things out. I also removed the 680nf and placed a 470nf there with the 2k7 stock resistor . That's helped also. The 470 is a lot bigger in size than the 680nf cap?



Hmmmm. I think were having a terminology issue here again. Filtering would be your giant dual caps standing up on your chassis. 
Edit 
Do you mean your coupling cap? It's a great way to keep things nice and tight especially with the resonance mod there to bring it back it a more efficient place on the amp.

The 680nf probably has a lower voltage rating them your 470nf is all.


----------



## mickeydg5

Yes, the Mojo Dijon capacitors are large. The 470nF being 630V will be much larger than the 680nF 160V. The large separation in voltage rating makes a big difference in package size.


----------



## mickeydg5

jd267 said:


> I put the 47pf back . Did not really notice that much difference. What did help was cutting the tremble peaking cap to 250pf on voltage divider resistors 470/470k.
> 
> I'm Just posting what I'm screwing with guys .
> 
> One MAIN Problem is the amp really turns to a hot sloppy mess when the drop c guitar gets plugged in OMG so loose and gross sounding lol. Lowering bass and resonance does not help.
> 
> It may be time for AKA the Mickey Mod. If you feel up to it Mickey could you make one of those nifty layouts for me? With the components off a mini switch ? I know I ask for a lot . Hole is already drilled





jd267 said:


> John I just tried your suggestion on the filter caps . I cut the fist one back to 2.2 and really helped things out. I also removed the 680nf and placed a 470nf there with the 2k7 stock resistor . That's helped also. The 470 is a lot bigger in size than the 680nf cap?



Changing the .022uF coupling capacitor to 2.2nF(.0022uF) and the .68uF cathode bypass to 470nF(.47uF) is similar and part of that switchable Mickey style modification.
The thing is will the switch and wiring put your amplifier back into oscillation territory if laid out and mounted near your INPUT or other components in that area?


----------



## RickyLee

john l said:


> That's your plate load and it controls the plate voltage that stage sees. 100k is typical there. Raising it will give you the impression of more gain even though that's not really what is happening. You might like the effect of a smaller value gain pot, lots of high gainers utilize these. Put a 1meg resistor across the gain pot and see if that starts things going in the right direction.



A question for John or Mickey as well as you guys know your theory. Sorry to jump into your thread JD as this is where the action is and my B+ thread is not getting any LOL.



I had a gain stage plate resistor value of 330K, cathode is 3.3K. My B+ going into/feeding the plate load was 273VDC. This gave me 128VDC on that triodes anode. The filtering node was shared by most of the other preamp gain stages as well. So I moved the filtering and B+ feed for this mentioned gain stage to just after the screens filtering node and created a new filtering node to just be used for this said gain stage. The B+ feed was now 407VDC. BUT, the voltage seen on that triodes anode just after that 330K plate only went up to 170VDC even though the B+ was increased by over 130VDC. Is this due to an equation that is proportional in its factor?


----------



## jd267

john l said:


> Yep. The circuit is laid out the way it is because that's the way the signal needs to flow, if you start adding mods to parts of the circuit that live down the road IE cathode follower and NFB loop... next to things like the inputs which are just extensions of your grids at the beginning you're going to have problems.
> Add to this that anything happening at the inputs gets re amplified many times over and it makes sense either steer clear of this area for certain mods.



Wish I new that before drilling two holes in the chassis 

Nik wants $50bucks for new faceplate. I have to order it now


----------



## jd267

mickeydg5 said:


> Changing the .022uF coupling capacitor to 2.2nF(.0022uF) and the .68uF cathode bypass to 470nF(.47uF) is similar and part of that switchable Mickey style modification.
> The thing is will the switch and wiring put your amplifier back into oscillation territory if laid out and mounted near your INPUT or other components in that area?



So the 47uf cut bass? It's hard to tell . I a/b the two caps and the .47 sounded clearer . The resonance pot is up max now though witch I don't like 

Guys how can I get more swing out of that resonance mod? More thump. Correct me if I'm wrong but could I do that mod with a cap across the ohm tap and NFR PLUS my resonance mod? I don't know how to make it more responsive


----------



## ampmadscientist

jd267 said:


> Really learning a lot guys . You were not kidding about lead dress geezz. So I had a squeal when pre amp volume was under 3 so I started moving around wires and about an hour later I found the problem. My saturation switch mod was causing it . I had to move the cap from it to right above v3 pre amp tube and run a shielded wire to the switch next to the input jack and noise is gone!! . I tryed to put a switch on front with stock slope resistor on one side and 47k on the other and it would not work it made the amp squeal again. Seems anything next to the input jack is an issue. Should I make a box shield for the inputs? I have to try dialing some gain out of the pre amp also I'm going to try john's resistor across the pre amp pot to bring it down to 500k and if it works I'll change the pot that should cut the gain right? The amp mushes out past 12oc lol



Now you're getting it. Takes practice doesn't it?

When the amp mushes out, it's because the low frequencies are distorting too much. (clue)


----------



## mickeydg5

RickyLee said:


> A question for John or Mickey as well as you guys know your theory. Sorry to jump into your thread JD as this is where the action is and my B+ thread is not getting any LOL.
> 
> I had a gain stage plate resistor value of 330K, cathode is 3.3K. My B+ going into/feeding the plate load was 273VDC. This gave me 128VDC on that triodes anode. The filtering node was shared by most of the other preamp gain stages as well. So I moved the filtering and B+ feed for this mentioned gain stage to just after the screens filtering node and created a new filtering node to just be used for this said gain stage. The B+ feed was now 407VDC. BUT, the voltage seen on that triodes anode just after that 330K plate only went up to 170VDC even though the B+ was increased by over 130VDC. Is this due to an equation that is proportional in its factor?


Voltages and currents as applied to branches determines those things. You moved your stage up to a higher B+ voltage point but it still shares power with all circuits connected in parallel and series. That stage will allow a certain amount of current based on its resistances/impedances. The other circuits will also be taking their associated currents based on their resistances/impedances developing their voltage drops. All of this works together and has to be figured out together according to the design scheme and Kirchoff's Laws or any other laws and theorems that may want to be applied.


----------



## mickeydg5

jd267 said:


> So the 47uf cut bass? It's hard to tell . I a/b the two caps and the .47 sounded clearer . The resonance pot is up max now though witch I don't like
> 
> Guys how can I get more swing out of that resonance mod? More thump. Correct me if I'm wrong but could I do that mod with a cap across the ohm tap and NFR PLUS my resonance mod? I don't know how to make it more responsive


Be careful of your referencing names and value callouts.
It is .47uF (point 47 microfarad). In general a larger value capacitor will provide more lower frequency. The .47uF will be a bit tighter having a little less low frequency than a .68uF or a 1uF.
A .33uF will be even tighter still.

I lost track of what is in your RESONANCE modification.
And is that what you guys were referring to earlier as the DEPTH modification also or is the DEPTH modification something else entirely?


----------



## RickyLee

mickeydg5 said:


> Voltages and currents as applied to branches determines those things. You moved your stage up to a higher B+ voltage point but it still shares power with all circuits connected in parallel and series. That stage will allow a certain amount of current based on its resistances/impedances. The other circuits will also be taking their associated currents based on their resistances/impedances developing their voltage drops. All of this works together and has to be figured out together according to the design scheme and Kirchoff's Laws or any other laws and theorems that may want to be applied.



Thanks for that. Basically, I am seeing normal operation there. I was expecting a bit higher voltage closer to 200V at that gain stage anode. Was just looking for a bit more headroom from that stage. I have some more info I will post in my B+ thread as to have it there for future reference for anyone looking - mainly my own bad memory.


----------



## jd267

mickeydg5 said:


> Be careful of your referencing names and value callouts.
> It is .47uF (point 47 microfarad). In general a larger value capacitor will provide more lower frequency. The .47uF will be a bit tighter having a little less low frequency than a .68uF or a 1uF. A .33uF will be even tighter still.
> 
> I lost track of what is in your RESONANCE modification.
> And is that what you guys were referring to earlier as the DEPTH modification also or is the DEPTH modification something else entirely?



I have a 1 meg audio taper pot with a 0.0047 cap or 0.0033 cap that runs to the 100k NFB resistor . Other wire from pot goes to me 8ohm tap.


----------



## jd267

Fellas I'm staring at a quad of shunghang 6550's and a quad of JJkt88's on my bench . Should we try those in this amp?


----------



## bulldozer1984

jd267 said:


> Fellas I'm staring at a quad of shunghang 6550's and a quad of JJkt88's on my bench . Should we try those in this amp?



No. 1 thing at a time man yeh ? Rushing into things without knowing what will happen is not a good idea. (AKA drilled holes in the faceplate) 

The first coupling cap really should be 2.2nF to tighten things up. 
Adjusting the shunt resistor at what would have been the first voltage divider before you added the new stage (so now the second voltage divider) to 220k is a really good idea too. Stock is 470k, change that to 220k. If that is too much change, try 330k.


----------



## jd267

bulldozer1984 said:


> No. 1 thing at a time man yeh ? Rushing into things without knowing what will happen is not a good idea. (AKA drilled holes in the faceplate)
> 
> The first coupling cap really should be 2.2nF to tighten things up.
> Adjusting the shunt resistor at what would have been the first voltage divider before you added the new stage (so now the second voltage divider) to 220k is a really good idea too. Stock is 470k, change that to 220k. If that is too much change, try 330k.



I put those back to 470k/470k . Why would you want to change them? What will it achieve 

The two 470k in a v configuration one to ground and one with tremble peak cap right?


----------



## bulldozer1984

jd267 said:


> I put those back to 470k/470k . Why would you want to change them? What will it achieve
> 
> The two 470k in a v configuration one to ground and one with tremble peak cap right?



Firstly, I did say to reduce the first coupling cap.

Re the shunt resistor, Sending more signal to ground tightens things up - but at the expense of possibly losing too much gain. Which is why i suggested several values. 

High gain amps are a balancing act. Sometimes you need to tweak each stage.


----------



## jd267

bulldozer1984 said:


> Firstly, I did say to reduce the first coupling cap.
> 
> Re the shunt resistor, Sending more signal to ground tightens things up - but at the expense of possibly losing too much gain. Which is why i suggested several values.
> 
> High gain amps are a balancing act. Sometimes you need to tweak each stage.



I here you on that man! I'll give it a try . I believe Mickey had me put a 220k there and remember it robbing a lot of gain so I put the stock values back. It's on the last layout he made of the mods


----------



## mickeydg5

I think everyone is loosing track of what resistor value is where now. Maybe the capacitors as well.


If you want to try to get a bit more low end from the amplifier then try moving the wire from your feedback and RESONANCE control to the OT 4 ohm secondary tap.


----------



## jd267

mickeydg5 said:


> I think everyone is loosing track of what resistor value is where now. Maybe the capacitors as well.
> 
> 
> If you want to try to get a bit more low end from the amplifier then try moving the wire from your feedback and RESONANCE control to the OT 4 ohm secondary tap.



I tried that Mickey I don't like the tone of the 4 ohm tap . I tried each tap and 8ohms is best to my ears.


----------



## mickeydg5

What brand and type power tubes are in the amplifier at this point?
What is the plate voltage and idle bias set to with these tubes?


----------



## jd267

Has el34 bht Ruby 's in it now running at about 35ma plate voltage I think / was 450.

I'll try the 6550's and kt's later just have to swap that 47k out


----------



## jd267

I'm going to install a switch on back with the correct resistors to swap from 6550 to el34 like I did to my cobra . Got to call classictone and see if I can run the 6550's to the proper bias . If not I'll stick to el34's . Hate biasing 6550's cold sounds like crap


----------



## mickeydg5

35mA is decent for 450VDC. I just wanted to make sure there was ample bias/current at idle to provide decent bass response.

6550 are usually biased just a tad more than EL34. So if you like 35mA for your 6CA7/EL34 types then 6550 would get 40ish or low 40's. (Depending on the actual tube set of course.)


----------



## jd267

I put those bastards up to 50ma give or take


----------



## bulldozer1984

mickeydg5 said:


> I think everyone is loosing track of what resistor value is where now. Maybe the capacitors as well.



It depends whether JD has changed them Since I confirmed them on page 6. If he has well then yeh we are all fuked 

Personally, I think a thinned out tight pre amp and then reclaiming bottom end in the power stage where it's clean is the best way. Especially for dropped tunings. But, everyone is different so these suggestions can only ever be a guide as JD will hear things differently etc.


----------



## jd267

All components are pretty much the same . Voltage dividers are back to stock. First coupling cap got changed that's it .


----------



## jd267

Amp really liked the 6550's . Did not have to change anything amp biased right up .. I also put a 390 resistor to ground In voltage divider . 390/470. Seemed to help


----------



## jd267

bulldozer1984 said:


> It depends whether JD has changed them Since I confirmed them on page 6. If he has well then yeh we are all fuked
> 
> Personally, I think a thinned out tight pre amp and then reclaiming bottom end in the power stage where it's clean is the best way. Especially for dropped tunings. But, everyone is different so these suggestions can only ever be a guide as JD will hear things differently etc.



I feel the same way about power amp bottom end . The 6550's added some and sounds good. The headroom helped also, I like the compression of the el34BHT but the amp is already compressed with the two 10 V zeners on. 

Amp is really sounding good . I will say this it crushes the 2203KK . I owned two in the past


----------



## jd267

Can't wait for that book to show up so I can read it like the bible . I really think this amp can sound better . Still missing something. Fellas why the 68k on NOW v3? What do the grid resistors do?


----------



## bulldozer1984

jd267 said:


> Can't wait for that book to show up so I can read it like the bible . I really think this amp can sound better . Still missing something. Fellas why the 68k on NOW v3? What do the grid resistors do?



68k grid resistor on what was V2a ?
I Already explained the grid resistors.


----------



## mickeydg5

jd267 said:


> Can't wait for that book to show up so I can read it like the bible . I really think this amp can sound better . Still missing something. Fellas why the 68k on NOW v3? What do the grid resistors do?


 It was there for good measure as a grid stopper to impede signal especially to help with noise or maybe oscillation back when the problem was major.

If it does not harm the tone much then leave it. It may also be lowered in value or removed if desired.

What resistors do you now have between V2 and V3?


----------



## jd267

Mickey how would they effect tone? Resistors between v2 and v3 what ones ?


----------



## mickeydg5

Everything affects tone in there.

Last I understood you had a 22nF coming off of the plate of the added gain stage (now V2 in order of signal) with that being tied to a 120k resistor to ground and from the junction of those two components a 68k grid stopper was to be placed providing connection to the next stage control grid of now V3.
All of that is shown on the last schematic markup I had posted.

The grid stopper impedes the signal to the valve control grid. The signal will be slightly weaker but most of all it will shelve or drop off some high frequency. A larger resistor there will drop more signal level while curtailing even more high frequency.


----------



## jd267

mickeydg5 said:


> Everything affects tone in there.
> 
> Last I understood you had a 22nF coming off of the plate of the added gain stage (now V2 in order of signal) with that being tied to a 120k resistor to ground and from the junction of those two components a 68k grid stopper was to be placed providing connection to the next stage control grid of now V3.
> All of that is shown on the last schematic markup I had posted.
> 
> The grid stopper impedes the signal to the valve control grid. The signal will be slightly weaker but most of all it will shelve or drop off some high frequency. A larger resistor there will drop more signal level while curtailing even more high frequency.



So if I want to ditch more (highs) I would use bigger grid resistors ?

I moved that 68k on v3 grid back to my fabed board .


----------



## mickeydg5

jd267 said:


> So if I want to ditch more (highs) I would use bigger grid resistors ?
> 
> I moved that 68k on v3 grid back to my fabed board .


 Yes that can and will help. Although it is not the only way.
One the board is ok but at critical times resistors mounted directly on the control grid socket pin is best case for impeding noise there.


----------



## jd267

mickeydg5 said:


> Yes that can and will help. Although it is not the only way.
> One the board is ok but at critical times resistors mounted directly on the control grid socket pin is best case for impeding noise there.



I just read that the grid resistors also act as a low pass filter .

Mickey what is happening to an amp when you put a OD up front as a clean boost . Why does it cause compression? What part of the amp does the OD effect the pre amp?


----------



## mickeydg5

jd267 said:


> I just read that the grid resistors also act as a low pass filter .
> 
> Mickey what is happening to an amp when you put a OD up front as a clean boost . Why does it cause compression? What part of the amp does the OD effect the pre amp?


Hee, hee, ha.
JD267, read between the lines. Or around or on the side of. 
If I say the resistor is impeding and curtailing high frequencies (blocking) then what do you have? Yes it is passing more low frequencies. So yes that indicates that it may be considered a type of low pass situation for frequency.

A clean boost provides signal gain which means there is an increase in signal amplitude. That added amplitude is feed to the next gain stage which works it beyond its normal limitations or linear range, also referred to as overdriving. The overdriven stage clips the peaks of the signal. That trimming of peaks provides compression of the signal levels.

A clean boost up front at the INPUT is going to affect every stage. The level or strength of the signal will determine where it begins to distort and compress most. If you slam the front end with a large boost then it will distort and compress at the first stage and so on.


----------



## jd267

mickeydg5 said:


> Hee, hee, ha.
> JD267, read between the lines. Or around or on the side of.
> If I say the resistor is impeding and curtailing high frequencies (blocking) then what do you have? Yes it is passing more low frequencies. So yes that indicates that it may be considered a type of low pass situation for frequency.
> 
> A clean boost provides signal gain which means there is an increase in signal amplitude. That added amplitude is feed to the next gain stage which works it beyond its normal limitations or linear range, also referred to as overdriving. The overdriven stage clips the peaks of the signal. That trimming of peaks provides compression of the signal levels.
> 
> A clean boost up front at the INPUT is going to affect every stage. The level or strength of the signal will determine where it begins to distort and compress most. If you slam the front end with a large boost then it will distort and compress at the first stage and so on.



 I guess that is the same thing lol. 

Would like to get some more compression out of my amp . Need it tighter


----------



## mickeydg5

Give us a description and pictures of what has been added and changed from the stock layout as of now.
Maybe we can figure how to get more compression/distortion out of it.


----------



## jd267

Everything is the same Mickey. Got a 1uf cap on 820ohm on v2b , went smaller on first coupling cap that's about it. What do you think I can try for some more compression ?


----------



## jd267




----------



## jd267

Voltage divider has a. 330k to ground not 120k.


----------



## mickeydg5

You may try a larger plate resistor value at the first stage; 150k to 220k value.
Maybe try a cathode bypass capacitor on second stage at the 10k; 100nf to 470nF value.
Try lowering the 1400pF plate bypass capacitor on added stage.

Experiment with those.

Watch for oscillation by monitoring idle bias at bias tubes.


----------



## jd267

mickeydg5 said:


> You may try a larger plate resistor value at the first stage; 150k to 220k value.
> Maybe try a cathode bypass capacitor on second stage at the 10k; 100nf to 470nF value.
> Try lowering the 1400pF plate bypass capacitor on added stage.
> 
> Experiment with those.
> 
> Watch for oscillation by monitoring idle bias at bias tubes.



By the first stage you mean the one we added right?


----------



## mickeydg5

jd267 said:


> By the first stage you mean the one we added right?



No, look at the schematic. The added stage is now the 3rd stage.


----------



## jd267

mickeydg5 said:


> No, look at the schematic. The added stage is now the 3rd stage.



I know that just wanted to make sure you meant v1


----------



## jd267

Mickey what is that 1400pf cap doing on the added stage?


----------



## mickeydg5

Remember we were trying to address high frequency oscillation. That was an attempt which may help but as much capacitor value may not be required since the lead dress/wire routing has been changed for better conditions.

The problem with large plate bypass capacitors is that it may rob the tone of some more frequency. So drop the value to keep extra signal as long as there are no feedback/oscillation conditions.


----------



## bulldozer1984

That 1400pf is a plate bypass cap. That is a large cap for that area. It is for reducing oscillation and can also be for reducing some unwanted high end. 

To reduce oscillation without robbing high end, try up to 250pF. But, if you are wanting to reduce high end then anything up to 1nF/1000pF can be used.

EDIT: Sorry Mickey I didn't realise you had posted. It was on another page.


----------



## mickeydg5

That is ok. You explained it a little in a different way.

Note that the 1400pF value was used with the 68k resistor while the 1000pF is used with the 100k to get a similar cutoff frequency.


----------



## jd267

mickeydg5 said:


> You may try a larger plate resistor value at the first stage; 150k to 220k value.
> Maybe try a cathode bypass capacitor on second stage at the 10k; 100nf to 470nF value.
> Try lowering the 1400pF plate bypass capacitor on added stage.
> 
> Experiment with those.
> 
> Watch for oscillation by monitoring idle bias at bias tubes.



Adding a bypass cap to the 10k (now 4k) sounded like poop. I went up on both plate resistors to 120k and really helped . Going to try 200k but don't have any at this time . I feel it shaped the low end a bit. The 1400pf cap I swapped for a 500pf but liked the 1400 better. Thanks mick


----------



## jd267

I feel the amp is coming together slowly. May try the el34's again now that my ears are use to the 6550's . I remember going from el34 to 6550 in my cobra then back to el34 and liked them better . Feel they add more compression.


----------



## jd267

I fired up my 2203 (Marshall) today and A/B my build with it . Apples to oranges lol it's funny how Modern my amp sounds now and how brutal it can get.


----------



## bulldozer1984

jd267 said:


> Adding a bypass cap to the 10k (now 4k) sounded like poop. I went up on both plate resistors to 120k and really helped . Going to try 200k but don't have any at this time . I feel it shaped the low end a bit. The 1400pf cap I swapped for a 500pf but liked the 1400 better. Thanks mick



High value plate resistors basically "starve" the triode stage of voltage. What happens is that yes you do add some gain but a side effect can be a looser sound with more compression. If that is what you want then great but just keep it mind.


----------



## jd267

bulldozer1984 said:


> High value plate resistors basically "starve" the triode stage of voltage. What happens is that yes you do add some gain but a side effect can be a looser sound with more compression. If that is what you want then great but just keep it mind.



Yes seemed to help a bit I only went up in value a little . The low end of the amp is kind of odd. I'm trying to get better shape out of it.


----------



## mickeydg5

What is the problem with the low end?
Describe in detail please.


----------



## jd267

mickeydg5 said:


> What is the problem with the low end?
> Describe in detail please.




I would say the lows need to be Shaped better.

Best I can describe it


----------



## mickeydg5

There are qualifiers for the words shape and better.


----------



## jd267

mickeydg5 said:


> There are qualifiers for the words shape and better.



Yes I know it's hard to explains though . Wish I could get my hands on a ubershall layout


----------



## hopkinwfg

hey jd... post us a vids of the amp ? or any raw tracks plz ?


----------



## jd267

hopkinwfg said:


> hey jd... post us a vids of the amp ? or any raw tracks plz ?



Ahh to much work to mic the cab and what not lol. Also my Laney ironheart 120 will be here tomorrow to I'll be tied up with that for a bit


----------



## hopkinwfg

jd267 said:


> Ahh to much work to mic the cab and what not lol. Also my Laney ironheart 120 will be here tomorrow to I'll be tied up with that for a bit



its cool to hear your success story haha ... i been wanting to try something like what you did too... but am already in process of doing my SLO diy...maybe someday.. but am very intrigued by your extra gain and bottom end you mentioned.. maybe dont need a too professional setup on recording but if could show us the tone you getting it be interesting


----------



## jd267

I will for sure man. It sounds like a ubershall now lol. Super high gain. Out of all my amps it has the most gain on tap hands down. Lol

The gain pot gets fuzzy past 4


----------



## bulldozer1984

jd267 said:


> The gain pot gets fuzzy past 4



Too much distorted low end is why it sounds fuzzy.. My amp is 4 stages and is usable right through the pots range. 

You need to attenuate more low end in the pre amp and bring it back in the power amp.


----------



## hopkinwfg

jd267 said:


> I will for sure man. It sounds like a ubershall now lol. Super high gain. Out of all my amps it has the most gain on tap hands down. Lol
> 
> The gain pot gets fuzzy past 4



uberschall? haha cool ! but maybe you can cut more gain out so it stay tight and focus when at high gain but still thicker meatier and a tad darker  keep us posted on your clips


----------



## jd267

hopkinwfg said:


> uberschall? haha cool ! but maybe you can cut more gain out so it stay tight and focus when at high gain but still thicker meatier and a tad darker  keep us posted on your clips



It is tight and focused and crazy thick . 

Question for The teachers of the thread . How can I make the fourth gain stage switchable ? Put a mini on off from grid wire? Or cathode pin? Just guessing lol.


With forth gain stage the amp don't clean up it very brutal and I love that about it . I would like to make the fourth stage switchable.


----------



## jd267

I would also like to make a mid shift mod kind of like what lee Jackson does . Just a on off on switch though. Off stock,right to left (other values). Guys got any experience with that?


----------



## jd267

bulldozer1984 said:


> Too much distorted low end is why it sounds fuzzy.. My amp is 4 stages and is usable right through the pots range.
> 
> You need to attenuate more low end in the pre amp and bring it back in the power amp.



How is that done? Why do you think it pre amp bass? Sounds like the amp just has a ton of gain on tap to me  after 4 it turns to a mess with gain. I would like to put the gain stage on a switch .


----------



## bulldozer1984

Before fuking around with switching, get the amp sounding right ! If the gain knob can't go past 4 without sounding like ass then you need to tweak it. Put up a clip and I'll tell you what needs to be done. We need to hear it to help You.


----------



## jd267

bulldozer1984 said:


> Before fuking around with switching, get the amp sounding right ! If the gain knob can't go past 4 without sounding like ass then you need to tweak it. Put up a clip and I'll tell you what needs to be done. We need to hear it to help You.



Cool I'll do that ! Would like to mic the cab but it's hard to talk to you guys at the same time . iPad clips blow


----------



## jd267

Seems John I's idea with 1m resistor from wiper to ground on 1m pre gain pot made the gain more useful. I just ordered a 500k pot to install.


----------



## jd267

Would like to dial the amp in more to my liking . I lowered the 820ohm cathode resistor to 1.5k and seemed to make a difference to my ears for the positive. The amp is missing something still but don't know what . I put back the 33k slope resistor also. The first stage plate resistors I went from 100k 100k to 120k/120k seemed to also help kind of. 

Making a clip won't really do much for you guys as it's hard to tell what an amp sounds like over the computer. Wish someone lived close that could check the amp out for some tips.


----------



## jd267

Do any of you guys have any high gain 2203 layouts with fourth pre amp tube mod that I could check out? Maybe get some ideas from.


----------



## jd267

What do you guys think of this? Herd from a good source it's a killer set up.


----------



## bulldozer1984

jd267 said:


> Would like to dial the amp in more to my liking . I lowered the 820ohm cathode resistor to 1.5k and seemed to make a difference to my ears for the positive. The amp is missing something still but don't know what . I put back the 33k slope resistor also. The first stage plate resistors I went from 100k 100k to 120k/120k seemed to also help kind of.
> 
> Making a clip won't really do much for you guys as it's hard to tell what an amp sounds like over the computer. Wish someone lived close that could check the amp out for some tips.



For Fuk sake man I'm trying to help you. You can spend half hour or even less throwing a mic up to the cab and pressing record. Just by listening to it I/we can make suggestions as to what needs to be changed tonally. If it is tonally balanced then we just need to reduce gain. If you can't do that one simple thing I'm done helping you. Sorry but you're asking for free help and not taking our advice and it's very frustrating.


----------



## jd267

All I'm saying is how can you say what needs to be changed and get a accurate feel for the amp threw your PC speakers lol. That's all I'm saying dude no need to act like a douch. What you here and what I hear are two different things . I herd your amp clips thats for sure NOT my take on high gain Nor the tone I'm after .


----------



## jd267

Fellas why the values on the added gain stage board? Should we try more Marshall type values ?

Edit . I played around with a few values on my added gain stage . The 65k Mickey suggested with 1400 cap on it I lowered the resistor value to 33k and seemed to compress the low end palm mutes . I guess the lower the value there the more compressed the lows will sound/feel. 


What I don't like about the tone is the palm mutes they sound sloppy . That's the best way I can describe it . In this case I would boost with my maxon as a clean boost but the amp is no longer able to be boosted . That's the reason why I suggested making it switchable or use low input for fourth stage . 

I should prob hang it up here and be done with the amp lol. But we all know how that goes . Thanks for all your help everyone !! Mickey you have been a big help and for sure a blessing to have you on the board .


----------



## bulldozer1984

Oh, insulting me now. Nice. FWIW, my amp is not an AFD clone anymore. That tone was something I wanted to achieve. I moved on after I achieved it. 

Your amp is sloppy on palm mutes because there is too much low end being distorted in the pre amp. Obviously I can't feel the amp over the Internet (did I ever say I could?) but I can listen to the tone and that can tell me a lot. But if you don't believe me, no worries.

I'm done with this thread, but on the way out I'll have a stab at fixing your amp. Swap out the now second stage coupling cap from 22nF down to 10nF and then if needed down to 2.2nF (or anywhere in between) Best of luck


----------



## tschrama

Clips and a schemo .. really go a long way getting help.

But indeed.... he's asking for free help and not taking any our advice and it's very frustrating.... I quit right after I noticed it.


----------



## jd267

bulldozer1984 said:


> Oh, insulting me now. Nice. FWIW, my amp is not an AFD clone anymore. That tone was something I wanted to achieve. I moved on after I achieved it.
> 
> Your amp is sloppy on palm mutes because there is too much low end being distorted in the pre amp. Obviously I can't feel the amp over the Internet (did I ever say I could?) but I can listen to the tone and that can tell me a lot. But if you don't believe me, no worries.
> 
> I'm done with this thread, but on the way out I'll have a stab at fixing your amp. Swap out the now second stage coupling cap from 22nF down to 10nF and then if needed down to 2.2nF (or anywhere in between) Best of luck




I just don't like being yelled at man I'm not some 22 year old kid . I tried swapping out the second cap to a 2.2 and all the tone was gone . I'll try the 10nf. Again was not insulting you just defending myself against your swearing at me etc.


----------



## jd267

tschrama said:


> Clips and a schemo .. really go a long way getting help.
> 
> But indeed.... he's asking for free help and not taking any our advice and it's very frustrating.... I quit right after I noticed it.



Free help? Is there a credit card swipe some where in this thread ? Lol


I built a high gain 2203 with the help of guys on this forum how much more do I need to listen than that? No sweat I'm sure I'll figure it out. Keep in mind I did build the amp and fix the main issues by my self .


----------



## jd267

bulldozer1984 said:


> Oh, insulting me now. Nice. FWIW, my amp is not an AFD clone anymore. That tone was something I wanted to achieve. I moved on after I achieved it.
> 
> Your amp is sloppy on palm mutes because there is too much low end being distorted in the pre amp. Obviously I can't feel the amp over the Internet (did I ever say I could?) but I can listen to the tone and that can tell me a lot. But if you don't believe me, no worries.
> 
> I'm done with this thread, but on the way out I'll have a stab at fixing your amp. Swap out the now second stage coupling cap from 22nF down to 10nF and then if needed down to 2.2nF (or anywhere in between) Best of luck




I ordered those 10nf caps you recommended I'll give that a go man . Thanks again no hard felling I just don't respond well to being yelled at .


----------



## jd267

Installed 500k pot,adjusted cathode resistors, tightened up the coupling cap on added gain stage and put the stock cap back that was changed, adjusted grid resistors, messed with bright cap values, swapped some pre amp tubes around and Bam!!! Just what I was looking for .I see what you guys meant by you change one thing and other values need tweaking . Think I'm ready to build Niks 2555 kit very soon ! Won't need to bother you Mickey so much this time lol you sure you don't need any amp parts? I will gladly buy what you need and drop ship them to you just let me know !!! Ended up with the 6550's biased about 46ma at idle . What a monster and super proud of myself for building it for my first build . Does not make much noise either ( your normal for a high gain build).


----------



## mickeydg5

Glad to hear it shaped up and you are liking it. 

Provide some video or audio if you get a chance. That is about all I would like. As I said before I need nothing but do appreciate the offer. 

I figured the 6550 would idle at about mid 40 mA. I may have mentioned that in this thread. 

Start a nice new thread with the 2555.


----------



## jd267

Of corse mojo sent me 10uf instead of 10pf


----------



## jd267

mickeydg5 said:


> Glad to hear it shaped up and you are liking it.
> 
> Provide some video or audio if you get a chance. That is about all I would like. As I said before I need nothing but do appreciate the offer.
> 
> I figured the 6550 would idle at about mid 40 mA. I may have mentioned that in this thread.
> 
> Start a nice new thread with the 2555.



I will for sure this fall. The amp will be a lot neater with it being my second build and being more knowledgeable.


----------



## jd267

mickeydg5 said:


> Glad to hear it shaped up and you are liking it.
> 
> Provide some video or audio if you get a chance. That is about all I would like. As I said before I need nothing but do appreciate the offer.
> 
> I figured the 6550 would idle at about mid 40 mA. I may have mentioned that in this thread.
> 
> Start a nice new thread with the 2555.




Agh it's not really what I wanted out of the amp to be honest. My stock 2203 with a boost still sounds better with more thump to it. I'm starting to think the added stage placement may be playing a role in what I don't like about the tone. Should I try to put it he half triode in front of V1? I'm sure there is more to it like you guys have been saying . Amps thin sounding . Ton of gain but it's not my type of gain . I know I ranted about it but I was just happy the amp worked lol. Wish I had a real tech that has a shop near by that builds amps that could help me out with my values


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## jd267

jd267 said:


> What do you guys think of this? Herd from a good source it's a killer set up.



Hey fellas why the .1uf caps for the PI ?


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## mickeydg5

jd267 said:


> Agh it's not really what I wanted out of the amp to be honest. My stock 2203 with a boost still sounds better with more thump to it. I'm starting to think the added stage placement may be playing a role in what I don't like about the tone. Should I try to put it he half triode in front of V1? I'm sure there is more to it like you guys have been saying . Amps thin sounding . Ton of gain but it's not my type of gain . I know I ranted about it but I was just happy the amp worked lol. Wish I had a real tech that has a shop near by that builds amps that could help me out with my values


Are you playing the same guitars, cables and cabinet with each amplifier?

There is more going on in the boost pedal than is happening with your added one gain stage.

It does not really matter if it is after or before V2 as long as you are holding the range of passed frequency but keeping it in check and applying gain. Honestly I do not know what is in your amplifier any longer. You had mentioned tweaking a bunch of things in the thread. You need to be explicit about what has been done and is in there.

The larger .1uF coupling capacitors after the PI in that layout provide more lower frequency to the power amplifier.


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## bulldozer1984

I know I said I was done in this thread,but I want to help.. As I have said before, clips would help. As I have also said, thin preamp, thick power amp is the key here. 

0.1uF PI coupling caps will add clean bottom end. Which is good. You can further enhance the bottom end (cleanly) by reducing the size of your "resonance cap". 2.2nF is good there. This cap should be in series with your negative feedback resistor. 

What is the value of your -Ve feedback resistor BTW.


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## neikeel

bulldozer1984 said:


> I As I have also said, thin preamp, thick power amp is the key here.
> 
> 0.1uF PI coupling caps will add clean bottom end. Which is good. You can further enhance the bottom end (cleanly) by reducing the size of your "resonance cap". 2.2nF is good there. This cap should be in series with your negative feedback resistor.
> 
> What is the value of your -Ve feedback resistor BTW.


 
..and if running 6550s with smaller grid resistors you need bigger PI caps to compensate for loss of low end,


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## Vostre Roy

Hey, I've followed that thread because some of the guys shared some awesome pieces of knowledge in here and they probably know more than I do, but I feel like I gotta add my grain of salt a bit ahaha

OP, I know your struggle, I got my first kit a bit over 2 years ago, back then I couldn't read a schematic, tell the difference between a resistor and I wasn't sure how to use a multimeter. Now I've got a working Weber 8CM100 (JCM800 2203 clone) wich I've moded a bit, though I haven't added a tube yet

If you plan on building more amp, or modding yours more, I can't stress enough how much knowing how to read and draw a schematic will help you (and us to help you). Also, check for Uncle Doug's video on youtube, very knowledgeable dude who is awesome at explaining his stuff. 

Also, when I mod my amp, I usually mod 1-2 things and then use the amp for a week or two, to really know if I like the mods or not. I also love to add switches that goes from a value to another, so I can hear the difference between the two at the flick of a switch (for preamp stuff, like bypass cap, cathode resistors or bright caps)

Cheers man! This thread has a lot of useful information, glad you made it and that a lot of people shared their knowledge


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## jd267

bulldozer1984 said:


> I know I said I was done in this thread,but I want to help.. As I have said before, clips would help. As I have also said, thin preamp, thick power amp is the key here.
> 
> 0.1uF PI coupling caps will add clean bottom end. Which is good. You can further enhance the bottom end (cleanly) by reducing the size of your "resonance cap". 2.2nF is good there. This cap should be in series with your negative feedback resistor.
> 
> What is the value of your -Ve feedback resistor BTW.



NfR is 100k stock. I tried other values but the amp became to smooth to my ears . I got my PC back up and running I'll try to make a miced clip. Im going to change those PI caps also in a few mins.


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## jd267

All values are back to mickeys layout he made . When I change values I do one or two at a time . I did not like what I had after hearing the amp for a bit so I put it all back the way Mickey had it . Mick you recommended lowering the grid resistors correct ? The stock 2203 did not use one on v2 .


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## bulldozer1984

jd267 said:


> NfR is 100k stock. I tried other values but the amp became to smooth to my ears . I got my PC back up and running I'll try to make a miced clip. Im going to change those PI caps also in a few mins.



Honestly, the 100k is your biggest problem. It got too smooth because you didn't tweak the rest of the amp around it. 
You should drop that to 47k and then tweak the preamp to get your hair back.


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## jd267

bulldozer1984 said:


> Honestly, the 100k is your biggest problem. It got too smooth because you didn't tweak the rest of the amp around it.
> You should drop that to 47k and then tweak the preamp to get your hair back.



Ahh I here you man thanks for the tip . I'll figure out what needs to be done over time if not I'll put it back to three stages and tweak that . The amp as of now really needs a gate to be half way quiet lol. For sure a learning experience on high gain .


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## bulldozer1984

All good bud.


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## jd267

I bothered you guys enough . Also it's hard explaining things I here threw text . Maybe if you guys lived close I would bring it by lol. So say I change the layout back to three stages I can bypass some cathode resistors with 1uf caps, and mess with plate resistors . Going up on plate resistor values creates more gain right? Or is it down


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## neikeel

jd267 said:


> I bothered you guys enough . Also it's hard explaining things I here threw text . Maybe if you guys lived close I would bring it by lol. So say I change the layout back to three stages I can bypass some cathode resistors with 1uf caps, and mess with plate resistors . Going up on plate resistor values creates more gain right? Or is it down


 
It gives you less clean headroom and the perception of more gain, depending on where your cathodes are biased.


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## mickeydg5

Since you are still messing with things and have seemed to get a handle on the noise/oscillation I will propose these new diagrams. This should give back or retain some of the low end.


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## jd267

neikeel said:


> It gives you less clean headroom and the perception of more gain, depending on where your cathodes are biased.



How do you check cathode bias? Off the cathode pin on socket?


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## jd267

mickeydg5 said:


> Since you are still messing with things and have seemed to get a handle on the noise/oscillation I will propose these new diagrams. This should give back or retain some of the low end.
> 
> View attachment 22676
> View attachment 22677



Thanks again Mickey your the best !


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## Jae

I know this is an older thread but I thought I'd chime in. I just finished a jcm800 2204 with the extra gain stage. But I did it without adding an extra tube. A lot more gain but like alot of people said it is very time consuming and you have to be very patient and most importantly know what you are doing. High gain amps I found was not an easy task. I did the initial thing of changing resistor values and even adding a bypass cap but that caused a host of problems like oscillations bad distortion etc. I went the route of adding an extra gain stage. From there you have to make sure you route the wires properly so that there is no oscillations etc. I even added a tube buffered effects loops, power scaling and a separate supply voltage to set up an amp that can take almost any 8 pin power tube. I've had the luxury now of experimenting with pretty much all the tubes from the tube store  
But again building it takes ALOT of pre thought and planning ahead. Some things may not fit properly in the chassis. You'll have to drill more holes. Even with the new slots you have to make sure any of the components with fit physically with the others. Took me about a year or more to get it right. Now I've finally built my second one. To get low noise minimal or no hum is a challenge as well. Good luck to anyone willing to take the effort and patience.


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## bulldozer1984

One of the things that you need to understand is the various methods used to filter frequencies in order to make it sound good. Anyone can make an amp produce a lot of distortion, but making it sound good seperates the men from the boys. You also need to experiment with supply voltages to find what works best for you. Getting yourself well versed in relation to biasing, low and high pass filters, voltage dividers etc is what is needed to be able to tweak it to your liking. 

All amps are different and so are people's ears.


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## mickeydg5

I am Mickeydg5 and I LIKE bulldozer's post.


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