First amp build - I need all the help you can give me!

waltschwarzkopf

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Hello, World!

It looks like my old 8040 is not going to recover, so I am thinking of salvaging most of the parts and building a new amp. The clean channel works, so I thought about rewiring the tube to use in the clean channel, but I guess that is going to be more work than starting from scratch.

Questions:
  1. How many tubes do I need for a 5-10W amp. It may be driving 1-2 12-inch Celestions.
  2. Do I need tubes in every section? Pre-amp, power amp, rectifier.
  3. Can I make it hybrid? Let's say, 1-2 tubes in the preamp and SS power stage.
I don't play too heavy, but I like some overdrive every once in a while. I thought about keeping it simple and doing a single channel, with little head room. My old G15RCD has two gain knobs, could I use, let's say a 12AU7 for (low) gain 1 and a 12AX7 for (high) gain 2?

I looked for some circuits online and there are plenty from all brands and also from DIY kits, so I cannot decide, as I haven't done this before. I am quite handy with electronics, I've modded all my guitars, and now I'm troubleshooting the terminally-ill 8040.

I found a couple of quite simple circuits online, I think they are Marshall-based, which is the sound that I'm aiming for.

LoW_Jim_V1_1.spl7 (tube-town.net)
You Can DIY!: Build a Single-Ended Guitar Tube Amplifier | audioXpress

I combined them into one, in order to keep it simple (audioXpress) but to have a 3-band EQ (LoW Jim), see attached file. I hope my circuit makes sense. I could re-purpose the transformer and some parts of the 8040 to power the new project, and even keep the SS power stage if you think this is a good idea.

What do you think?

Any help and advice will be greatly appreciated! Feel free to recommend a circuit or to modify the one I made. I wanted to upload the actual circuit .diy file, but it is not allowed.

Cheers,
Walt
 

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Marcomel79

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Hey man, ive only built one amp, the px18 from tube town and i can tell you that All components were very good quality and very good price. Optimal for first time build. They offer schematic and a layout diagram, but no step by step instruction. Pretty easy to follow though. And if you get stuck, you got the whole forum to get help from. Good luck whatever you choose.

Marco
 
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South Park

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A good first amp to build is X84 high octane . Do not get over your head with this single ended single channel . The things you will learn you will need for bigger stuff .
 

waltschwarzkopf

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Hey man, ive only built one amp, the px18 from tube town and i can tell you that All components were very good quality and very good price. Optimal for first time build. They offer schematic and a layout diagram, but no step by step instruction. Pretty easy to follow though. And if you get stuck, you got the whole forum to get help from. Good luck whatever you choose.

Marco
That looks great, I had seem their page but rather focused more on the tiny heads.

One question: What is the deal with all four inputs? I don't think you can connect for guitars simultaneously to the same amp, right? Anyway, since most people always use a patch cable to jump both channels, wouldn't it be easier to just wire it that way and have a single input?
 

waltschwarzkopf

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A good first amp to build is X84 high octane . Do not get over your head with this single ended single channel . The things you will learn you will need for bigger stuff .

That looks neat, although I don't know if I found the right one. Could you share a link to the schematics you used?
 

South Park

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That looks neat, although I don't know if I found the right one. Could you share a link to the schematics you used?
The web site is AX84 HI octane it is a high gain single ended amp all the info is thar on the build I built one . Sorry about the spelling
 

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waltschwarzkopf

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A good first amp to build is X84 high octane . Do not get over your head with this single ended single channel . The things you will learn you will need for bigger stuff .

I found that the P1 AX84.com - The Cooperative Tube Guitar Amp Project is actually simple and recommended for beginners, I might go for that one. It's a pity that they don't make the kits anymore, so I'll have to assemble the parts by myself. But the amp layout has everything I want. Thanks for the tip!
 

ibmorjamn

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Well , it is totally up to you. I started with a single ended amp but I was not that happy with it. I would listen to some DYI builds on YouTube and decide a amp style you like. Every amp site I have seen suggests your first build be simple . Probably either a Fender or a Marshall.
 

2L man

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My first amp build was SEPlex by dvnator which he documented very well to his pages. It is single ended amp and has six potentiometers which all have effect to sound so it is versatile and sound quite good and marshally using very low volume and it is I play more than other.

Depending of output transformer current rating it can be build different max powers but for about max 10W Hammond 125DSE and EL34, 6L6GC or KT66 can be used when power supply outputs about 400VDC/100mA. For EL84 and 6V6GT H125CSE and about 350VAC produce about 4W.
 

Marcomel79

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That looks great, I had seem their page but rather focused more on the tiny heads.

One question: What is the deal with all four inputs? I don't think you can connect for guitars simultaneously to the same amp, right? Anyway, since most people always use a patch cable to jump both channels, wouldn't it be easier to just wire it that way and have a single input?
The four inputs are two separate channels, each one has a high and low sensitivity. If you patch them together you can blend the sounds.
 

Pete Farrington

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What is the deal with all four inputs? I don't think you can connect for guitars simultaneously to the same amp, right?
The intention back in the early 50s when the concepts coalesced into the now classic valve amps was indeed to facilitate a whole string band (guitars, bass, mic) to plug into the same amp.
 

waltschwarzkopf

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The intention back in the early 50s when the concepts coalesced into the now classic valve amps was indeed to facilitate a whole string band (guitars, bass, mic) to plug into the same amp.
Alright, that's what I thought.
So, if we want to use the amp for only one guitar, would it make sense two wire both channels directly together to the same input jack?
 

Matthews Guitars

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If you go with a single ended output stage, you can build an all tube amp with decent gain with three tubes. Just build a hotrodded plexi front end without a phase inverter and a single ended output using a 6V6.

Run V1's two triodes in series to stack the gain, insert a jack between them for a low gain clean channel, run the second stage output into a phase inverter (V2) and then thru the tone stack, feed that to the output transformer. Of course you'll want to add volume and gain controls.
 

Pete Farrington

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we want to use the amp for only one guitar, would it make sense two wire both channels directly together to the same input jack?
That’s certainly an option. I prefer to use a separate jack for each channel, but use their internal switching to feed both channels if only the #1 jack is used.
That allows me to use an external ABY box to switch between channels when I’m playing with the band.
But when noodling around at home, I can just plug into the #1 jack and blend the channels as desired.

Run V1's two triodes in series to stack the gain
To me, stack implies an additive effect, eg stacking HT caps to double the voltage rating (and halve the effective capacitance).
Whereas cascading gain stages results in the total gain being the product of the individual stages, eg cascading 2 stages, each with a gain of ,50 results in a combined gain of 2500 (and a big smile :)).
 

Chris-in-LA

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Alright, that's what I thought.
So, if we want to use the amp for only one guitar, would it make sense two wire both channels directly together to the same input jack?
No, no sense. Jumping the channels just adds mud and reduces clarity, leave them separate. The high treble channel is where the grind comes from.
 

Wormscoffer

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I have an AX84HO (High Octane) that I started years ago. I'll finish it once I'm done with the PiDP11 that has me fully occupied. There's plenty of demos of them on YouTube and the site, though seemingly dormant, has plenty of info.
 

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