# Jumping channels on 1959



## Jodyzuza

Is there any preference on jumping the channels, I.e. Which inputs to jump? Or how about using a Y cable of sorts?
This is my first plexi so trying to learn how to use it lol


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## dreyn77

Great BUY! 

have fun with it. 

Personally I just plug the vintage pickups into the channel with the most 'gain' sound, and hot modern pickups into the other 'low input' channel. Pedals also go into this input aswell. 
If you put them into the high input that makes 'more sound' than it's suppose to make. it's for extra effect and you might notice more 'faults' like 'hiss' and 'noise'.

If you've got a bright sound, it's suppose to be bright. 

because you're suppose to use the guitar's tone pot and vol to get other sounds.


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## Rolandj00

I use a George L's jumper ,It is a perfect fit made just for the 4 input heads.I am not sure if it matters but I jump from top of channel 1 to bottom of channel 2 and plug my axe into bottom of channel 1. this gives the ability to blend the 2 channels . It gives the best tone with an even amount of cut and bottom end for me, but thats with no pedals, just an absolute monster thru my 1986 JCM 800 brown grill full stack cabs, both of my wifes cats along with my mother in law have moved out of the house , and I have this monster to thank congrats on obtaining a great head, crank it and shake the walls!!!!


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## Jason77

Typically, people plug into the bright 1 input and run the jumper from bottom left to top right. But you can do any combo you like. Here's a cool trick you may not know about: because of how the two channels are tied together at the mixing stage, the unused channel will still have an affect on the channel you're plugged into. So, if you're plugged into the bright channel only, you can add some girth by turning up the normal channel volume. Likewise, if you're plugged into the normal channel, you can brighten it up by turning up the bright channel volume.


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## kamran

i dont jumper, i feel like it adds mud, but then again im going for a punchy rock tone, not a bluesy warm tone. if youre going for ac/dc or evh style plexi tones, keep in mind that neither of them jumper. it sounds very bright, but its great for a band mix.

i should add that with my modded superlead i couldnt jumper even if i wanted to, but when it was stock i still didnt enjoy the jumpered sound.


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## Rolandj00

what mod do you have on your super that makes it unable to jumper??


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## Joshabr1

No jumper here. But I use a superbass mostly. I didn't jumper my superleads either. Channel 1 high input for me. It worked for Koss. I use old greenbacks and 65s thru basketweaves so that adds plenty of low end. But u have it in front of ya. Try every combination u can and let your own ears decide.


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## AlvisX

I jump the channels ALL the time. I get no "mud" ...just TONE ......
Makes all the guitars sound "right"


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## kamran

AlvisX said:


> I jump the channels ALL the time. I get no "mud" ...just TONE ......
> Makes all the guitars sound "right"



To each his own 

If I played more lrads, or more stuff your style I'd most likely jumper also, being a power chord rocker it doesn't really get me going though the same way just plugging it the bright channel (Either high or low) does. 

And to whoever asked, I have the Dookie mod, not sure what's goino on internally but they plug all of the inputs except for one when the do the mod.


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## sct13

What I have been told... and it works, 

If there is a bright cap that makes the bright channel very bright then jumping the into the second channel will add gain without it being flubby, also the bright cap is taken out of the circuit when turned up past 8 or so. 

So jumping the channels is mostly for when your not playing at full volume. I have considered trying a bright cap on channel two just to see if some of that mud can be cleaned up. not really sure what will happen actually. A Superbass will only get more bassy when jumpered. 

So if there is a sweet spot on you channel one but you want a little more flavor jumper it and increase volume slowly. 

Also the two channels do mix without a jumper as stated earlier...true many don't know about that.


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## kamran

sct13 said:


> What I have been told... and it works,
> 
> If there is a bright cap that makes the bright channel very bright then jumping the into the second channel will add gain without it being flubby, also the bright cap is taken out of the circuit when turned up past 8 or so.
> 
> So jumping the channels is mostly for when your not playing at full volume. I have considered trying a bright cap on channel two just to see if some of that mud can be cleaned up. not really sure what will happen actually. A Superbass will only get more bassy when jumpered.
> 
> So if there is a sweet spot on you channel one but you want a little more flavor jumper it and increase volume slowly.
> 
> Also the two channels do mix without a jumper as stated earlier...true many don't know about that.



While it may sometimes sound like it jumping channels doesn't add any gain


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## AlvisX

I like the sound of a shared cathode , all my 4 hole amps end up with it and I think that may be a part of what make jumpin channels work so well for me .
Brite cap to taste . My 1959 has a 470pf at the moment and I think no cap over the mixer. My volumes usually dont go past 6 ....which is plenty loud . I try to set things where the Les Paul is on the edge of feedin back on an A power chord ...to where the teles / strats clean straight up with just a little back off in the guitar volume. I think that was what did it for me ....the teles thru just the brite channel were just too harsh, but combined with the 'norm" channel ,made em fat ,but still twangy
I dont get / do the "dime" thing


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## sct13

kamran said:


> While it may sometimes sound like it jumping channels doesn't add any gain



Didn't mean it in the technical sense, nextime I'll be more specific as to not spread bad info. "sounds bigger or fuller" is more the proper statment.


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## sct13

AlvisX said:


> I like the sound of a shared cathode , all my 4 hole amps end up with it and I think that may be a part of what make jumpin channels work so well for me .
> Brite cap to taste . My 1959 has a 470pf at the moment and I think no cap over the mixer. My volumes usually dont go past 6 ....which is plenty loud . I try to set things where the Les Paul is on the edge of feedin back on an A power chord ...to where the teles / strats clean straight up with just a little back off in the guitar volume. I think that was what did it for me ....the teles thru just the brite channel were just too harsh, but combined with the 'norm" channel ,made em fat ,but still twangy
> I dont get / do the "dime" thing



I like to "dime" it just to get the agression out.... kind of rebellious, wanton foolery...

But finding those sweetspots is imparitive to good tone managment. and thats per guitar types and styles of playing.


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## NativH

sct13 said:


> I like to "dime" it just to get the agression out.... kind of rebellious, wanton foolery...


Sometimes, you just gotta do what you just gotta do. Marshalls can be cathartic.


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## LAARS

Here is how I do it. Trace from Voodoo amps has this posted on his website.


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## kamran

AlvisX said:


> I like the sound of a shared cathode , all my 4 hole amps end up with it and I think that may be a part of what make jumpin channels work so well for me .
> Brite cap to taste . My 1959 has a 470pf at the moment and I think no cap over the mixer. My volumes usually dont go past 6 ....which is plenty loud . I try to set things where the Les Paul is on the edge of feedin back on an A power chord ...to where the teles / strats clean straight up with just a little back off in the guitar volume. I think that was what did it for me ....the teles thru just the brite channel were just too harsh, but combined with the 'norm" channel ,made em fat ,but still twangy
> I dont get / do the "dime" thing



I don't dime them either. Sounds like butt to me. My sweet spot is 4, still nice and articulate but screaming. 

Funny thiugh, we have the same way of judging our levels, except instead of setting it on the verge of the a chord feeding back, I turn it up until it feeds back with control easily. 

By the way, fat and twangy is my middle name 
That's why P90s are my best friend.


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## usednabused

George L's and the standard jumping procedure...there is a reason you see everyone in the world doing it that way!


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## tone seaker

To my ears jumping takes gain away. I don't jump but turn up the unused bass volume to 7 or 8 and it thickens it up without being jumped to


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## AlvisX

I pretty much use this amp only outdoors (unless I use if for bass) 
Here's a couple clips while tuning sh*t up for a few last outdoor shows this year
Channels jumped ,volumes on 5 / Bass 4 / Mid 7 / treb 4 / pres 6 / Lar-Mar to where the dishes in the sink jUST rattle .
WGS 65's

LP
[ame="http://www.youtube.com/watch?v=x6qIAouV72k"]1973 Marshall 1959 & '56 Les Paul Jr - YouTube[/ame]

Tele
http://www.youtube.com/watch?v=KA54ye6C7Jk


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## Georgiatec

If you run FX in the jumper "loop" you can totally change what channel II sounds like. Not the same amp I know, but I run my 2061x Guitar>top lead input, bottom lead input>Boss CE-2>TC Flashback Delay>TC Hall Of Fame Reverb> top bass input. I then use the bass volume and tone to mix the wet signal with the dry signal from the lead channel.
Pretty sure the four hole 50/100 watters work the same way. 
If you use an A/B/Y switch you can run an o/d in front of the first input without affecting the second channel. The four inputs gives so many possibilities


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## Joshabr1

kamran said:


> I don't dime them either. Sounds like butt to me. My sweet spot is 4, still nice and articulate but screaming.
> 
> Funny thiugh, we have the same way of judging our levels, except instead of setting it on the verge of the a chord feeding back, I turn it up until it feeds back with control easily.
> 
> By the way, fat and twangy is my middle name
> That's why P90s are my best friend.



Yep. My shared cathode lead spec other wise loves it around 4-6. All the grind I would ever need. And unholy loud. No need to turn up past that to me.


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## AlvisX

Joshabr1 said:


> Yep. My shared cathode lead spec other wise loves it around 4-6. All the grind I would ever need. And unholy loud. No need to turn up past that to me.



shared cathode , major part the "plexi" puzzle IMO


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## Coronado

I just picked up a 1978 and I'm new to the whole 4 input thing, but I gotta say, I love all of the options! Georgiatec was really helpful and gave me the rundown on how to loop effects into my jump. I don't have an A/B/Y splitter yet, so I tried running some OD through my loop as well (bottom number 1 to chain then up to top #2 input). I guess there are so many ways to do this (as Georgiatec mentioned). Are there other ways as well to add OD while using a jumper? I know when I crank it up a bit the amps gain is fantastic, but I also like to add some OD at lower volumes as well. 

As always, thanks for all the help and advice!


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## Georgiatec

Try a few o/d or distortion pedals in front of the first input to begin with. The pedal of choice back in the day (mid-late '70's) was the MXR distortion+. The original Boss OD1 also had good (more subtle) results. There are so many available these days that you could be spoilt for choice. A lot of the tones from the past were happy accidents due to the limits of what was actually available.


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## adamzapple

I've gone through different combinations on my 1959HW. Lead input only, normal input only, jumpered and Y-cord. I like all four for different situations. Right now, I'm using lead input only. I dime all the controls, use a Rivera RockCrusher to control the output and use guitar volume/tone to control the tone. From bright to dark it goes: lead>Y-cord>jumpered>normal. There's a place for all of them. The Lead channel has plenty of bass as long as you turn it up to 10, back off the guitar volume to 5-7 and tone 2-4.


__________________
'03 Gibson Les Paul R7 Stinger
'96 Gibson Les Paul R8 Iced Tea
'00 Fender Stratocaster American Standard
'10 Fender 52 Telecaster Vintage Reissue
'12 Gibson J45

Marshall 1959HW
Marshall 1960TV
Marshall Class 5 Mark II
Fender 57 Twin Reissue


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## DaDoc

I like using a Y cable myself, Volume on channel one at 3 1/2 and channel two at 4, plenty of volume! I go from my pedalboard to a Fender Tube Reverb then through the Y cable to the amp, and use either a Maxon OD-9 Tubescreamer or B.K. Butler Tube Driver for distortion, sometimes along with a Roger Mayer Octavia. The Tube Driver gets the most use, it's the best distortion unit I've ever heard, and I've heard a bunch of 'em!

Besides, if it works for EJ, it works for me..


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## Coronado

Thats one area I've been a tad confused about -if I'm jumping cables (guitar into top #1 left, jumping from bottom left to top right), is it better to adjust _both _volumes, or better to just adjust the guitar input? (top left). 

Thanks!
Ray


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## jack daniels

A lot of guys jumper from the lo input sensitivity bright channel to the hi input sensitivity normal channel and inject the guitar signal into the hi input sensitivity bright channel. After watching Jamie Humphries (Lick Library tutor) jumper his 4 holer Marshall for a Gary Moore video, I now do mine like Jamie does all the time which is.... Guitar signal into lo input sensitivity bright channel, and jumper from hi input sensitivity bright channel to lo input sensitivity normal channel. For whatever reason, this works best for me and my applications.


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## shane159

AlvisX said:


> I jump the channels ALL the time. I get no "mud" ...just TONE ......
> Makes all the guitars sound "right"



Same here.


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## FutureProf88

I've tried jumping and not jumping. It almost depends on the day but I think that I prefer just plugging in to the high channel and then turning the normal channel up. This does change the tone of the high channel a bit. 

I disagree that jumping gives you bluesy tones. I think that jumping the channels makes the amp much punchier and more aggressive sounding. Just the normal channel will give the "bluesiest" tone while just the bright channel will give a nice blues/rock tone all the way up to early hard rock when cranked.


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## sct13

Jumping tends to add more lows to the bright or more bright to the normal. depending on which side your plugged into. 

The knobs themselves are interactive as well without jumping. 

I usually do not like the results of jumping, It adds a flubby tone I can hear as intrusive.


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## stalefish

FutureProf88 said:


> I've tried jumping and not jumping. It almost depends on the day but I think that I prefer just plugging in to the high channel and then turning the normal channel up. This does change the tone of the high channel a bit.
> 
> I disagree that jumping gives you bluesy tones. I think that jumping the channels makes the amp much punchier and more aggressive sounding. Just the normal channel will give the "bluesiest" tone while just the bright channel will give a nice blues/rock tone all the way up to early hard rock when cranked.



Yup. I prefer not to jump, or when I do, I just tickle in a little of the normal vol. 

Another thing.....when using humbuckers, jumping channels, and cranking volumes, back the bass off. Some guys roll all the way down to 0. The way the tone controls interact with the gain stage, the more you crank it, rolling off the bass knob helps keep things tidy.


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## Joshabr1

On shared cathode amps jumping makes them muddy to me. I think it matters much what ur set up is. If u have 2 basketweaves shared cathode and pafs jumping wouldn't make sense. If u had to cabs full of 75s and a strat jumping would be a good option.


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## Joshabr1

I have 2 basketweaves with 003 cones and a les paul with paf pickups w a superbass (100pf) bright cap. I plug into bright channel and eq presence 6 bass0 mid 10 treb 10 bright vol 9 normal vol about half up. This setup gets a very kossoff sounding tone. Now with the strat it's a totally different set up.


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## Maklaca

Coronado said:


> Thats one area I've been a tad confused about -if I'm jumping cables (guitar into top #1 left, jumping from bottom left to top right), is it better to adjust _both _volumes, or better to just adjust the guitar input? (top left).
> 
> Thanks!
> Ray



When jumping, you will want to use both volumes. Most people use jumpers because they feel the bright channel is too bright and the other channel is not brought enough.
Jumping connects the two channels in parallel. allowing you to dial in the right mix of each channel to get the tone you like.


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## mickeydg5

Plugging into the NORMAL channel and then jumping to the BRIGHT channel will attenuate more high frequency. If you want to retain more highs from the guitar then plug into opposite.

It does not matter if you plug into a HIGH or LOW input since plugging into both jacks of one channel will provide only the lower dB input.
It does matter where the jumper is plugged into with HIGH providing higher dB and LOW having the less dB input.


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## ampmadscientist

Jodyzuza said:


> Is there any preference on jumping the channels, I.e. Which inputs to jump? Or how about using a Y cable of sorts?
> This is my first plexi so trying to learn how to use it lol



Jumping the channels allows lows (from one channel)
and highs (from the other channel)
To round out the tones, highs and lows together...

But it barely adds any gain. About 20% and hardly anything to brag about.

*Using a Plexi:
you have to crank it wide open, to cause the output tubes to overdrive.*
(it's louder than God)
Then, use an attenuator to lower the volume.
(the attenuator IS the master volume)

*Otherwise, if you don't play it WIDE open, there is no point in owning a Plexi.*

If you play a Plexi on LOW volume
It's very clean and has no guts whatsoever.

Trying for a great sound at low volume?
So, most people who bought a Plexi...bought the wrong amp.

Most people do not understand the purpose and use of the Plexi.
They wind up using distortion pedals to correct the misunderstandings.

And if you are using distortion pedals, you missed the point of a Plexi entirely.


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## FutureProf88

ampmadscientist said:


> Jumping the channels allows lows (from one channel)
> and highs (from the other channel)
> To round out the tones, highs and lows together...
> 
> But it barely adds any gain. About 20% and hardly anything to brag about.
> 
> *Using a Plexi:
> you have to crank it wide open, to cause the output tubes to overdrive.*
> (it's louder than God)
> Then, use an attenuator to lower the volume.
> (the attenuator IS the master volume)
> 
> *Otherwise, if you don't play it WIDE open, there is no point in owning a Plexi.*
> 
> If you play a Plexi on LOW volume
> It's very clean and has no guts whatsoever.
> 
> Trying for a great sound at low volume?
> So, most people who bought a Plexi...bought the wrong amp.
> 
> Most people do not understand the purpose and use of the Plexi.
> They wind up using distortion pedals to correct the misunderstandings.
> 
> And if you are using distortion pedals, you missed the point of a Plexi entirely.



Angus ran his on ~5-6.


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## jack daniels

sct13 said:


> Jumping tends to add more lows to the bright or more bright to the normal. depending on which side your plugged into.
> 
> The knobs themselves are interactive as well without jumping.
> 
> I usually do not like the results of jumping, It adds a flubby tone I can hear as intrusive.



** If your Marshall has a shared cathode configuration **


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## sct13

I am referring to this one....the flubby isn't too bad, but I don't like it in the mix


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## jack daniels

sct13 said:


> I am referring to this one....the flubby isn't too bad, but I don't like it in the mix



It appears as though you have the split cathode circuit minus the 2K7 resistor piggybacked across the .68uF capacitor (lead circuit). Is the amp tube rectified by chance since you speak of flubbiness?

Here's what I highly recommend for "flubiness removal" even w/tube rectified circuits.....






Ayan Smooth-n-Slim Mark II:

From Gil Ayan:
What do you get when you cross a degreed engineer and a musician? Trouble for sure, but over the years I have sometimes been able to sort of merge these two disciplines with good results. For a while I was primarily interested in optimizing the performance of my own gear, and that led to hot-rodding some guitars and performing mods on a couple of my amps. This year, I set out to try to reach an overall improvement in tone by tinkering with some mods, and accidentally stumbled on the idea of designing a signal conditioning device that could be used by those with a sophisticated taste for tone who are never quite satisfied with the performance of their rigs. The premise here is that you are a guitar player, you use vacuum tube amplifiers, you are not happy with the current supply of tubes, and you choke at the thought of spending some $75 per tube on N.O.S. 

Those who have old Fenders may have had this experience: you outfit your Twin with a new quartet of 6L6 GCs and you find the bottom end is loose and muddy, and the top end sounds cold and shrill. Yes, it happens to a lot of us regardless of whether the amp uses 6L6s, EL34s, 6V6s, etc. If you fall in this category, then Smooth & Slim may be for you. Comments from those who have tried my two prototype versions of the unit have been very favorable: "the reason I like my distortion with the Smooth & Slim so much is because my amp actually doesn't sound distorted!" (yes, taken literally it may seem like a contradiction, but if you dig good tone you will know exactly what this guy is saying!); or "I love what this thing does to my Deluxe Reverb, it seems to enhance the sustain and upper midrange in a very musical way." Okay, okay, so much for plugging my own creation, but to be honest with you, it is the best companion for my Boogie Mark I.

From Gil's Partner, Carlos Holguin:
My name is Carlos Holguin and I've been playing music, first as a bass player and then as a guitar player, for over 25 years. I play mostly rock, but also blues (doesn't everyone?), some Latin, classical, and folksy finger-pickin' stuff. 

In my early days I went through a number of the usual amps: among them a Fender Super Reverb, Twin Reverb, Bassman, and a great old Gibson amp with two big knobs on the front and a single 15" speaker, which I could kick myself for unloading. Although all of these amps could cop a decent clean sound, what I really wanted was a set-up that would do that endless sustain thing, a la Carlos Santana. 

In about 1974, I read a review in Guitar Player Magazine - the Alembic Report, as it was called - of a new amp put out by Mesa Engineering. Carlos Santana and John McLaughlin were playing them, and according to McLaughlin, it was real easy to get endless sustain out of the little combos. There was no place to demo one of these amps down here in L.A. because they were being hand-built, a few at a time, in a garage up in northern California, and no music stores had'em yet. It was a leap of faith, but I went ahead and sold all my gear, added some cash from my gas station job, and put in an order. 

Now, back in those days Mesa offered a number of options to anyone buying their amps. You could get reverb, a graphic EQ, a JBL speaker, or an extra pair of power tubes, which you could switch on to kick the amp up from 60 to 100 watts. If you wanted one of these options, it would set you back $80 bucks, two options $160, and so on. All I could manage to scrape up was enough for one option, and since I already had an old Fender outboard reverb that I liked - and I sure didn't want my partners blowing my new amp away with their Twins - I opted for the 100 watt switch. That little Boogie combo has been my main amp ever since. 

Soon, Mesa became famous and started pumping out with a bunch of other models, and other amp companies started copying the Boogie's cascaded preamp. But when they first came out, these little Boogies had something no other amp had: a bunch of extra gain stages that would make your guitar sustain for days. The amp was also very heavy on midrange, and its basic tone therefore contrasted quite a bit with, say, the scooped midrange sound made famous by Marshall amps. Both are classic great sounds, but very different. 

Anyway, after tweaking around with this amp for a while, it was clear that the lead sound just wouldn't happen if the bass control was set at anything over 2. Running it up any higher would cause the amp to spew out this muddy, sloppy distortion that just sucked. This is commonly described as a "farty" or "flabby" sound, and it's pretty ugly indeed. For many years, I just zeroed out the bass control and adjusted the treble and middle knobs to taste. I thought the amp sounded pretty good this way, especially with a humbucker-equipped guitar, but the tone was still a bit thin for my taste. It seems that dialing out the bass robbed bottom end, but that was nevertheless a better choice that the flabby bottom. Over the years I tried many things to work around this compromise: expensive NOS tubes, different pickups, strings, stomp boxes, and so on. Nothing worked too well, so my final solution was to play through two amps: a Fender set clean and bassy, and the Boogie, overdriven, with lots of mids and highs. This gave me what I considered a great sound in the toughest venues, such as the great outdoors, but it was a royal pain to haul around all that extra gear, and I'm not getting any younger. 

Then, thanks to the Internet, I managed to hook up with Gil Ayan. [He's the first guy I ever met face-to-face after exchanging messages over the Internet, kinda weird when you don't have a face to go with a name, but that's another topic.] He's an electrical engineer, a tone fanatic, and a damn good guitar picker. He also favors Boogie Marks, and he'd apparently been ruminating on the thin-or-flabby dilemma for some time. He posted a couple of messages theorizing that, somewhat like Jim Marshall later implemented in his high-gain line of amps, if one were to realign selected portions of those bass frequencies before hitting the gain stages, one could get good, smooth distortion, and then the bass control could be turned up without adding flabby bottom. Gil's set out to achieve these results without the need for amplifier modifications, and eventually came up with the box that pulls off this trick, called Smooth & Slim. 

Well, it worked... I mean, it really worked. The distortion on the Boogie immediately became way smoother, to the point where the amp didn't sound, well, distorted. And, because I could now run up the bass without flabbiness, I recovered a good deal of the bottom end I had been losing all those years. The amp started singing with a very cool sweetness. I got really excited and spent some time comparing the tone of the amp through the Smooth & Slim and Santana's "Europa" sound off the Moonflower disk. Now, that's a great guitar tone without a doubt, but I could still hear a little raspy edge to his distortion, whereas mine had all of the good stuff, but none of that objectionable rasp. Wow! Another bonus was that I could now use my single-coil Fender Stratocaster and make it sound great as well - Strat users are probably very familiar with the rather shrill tone that results when using these guitars in conjunction with Boogies set for overdrive. When Gil asked me to help him build a few of the boxes, I was more than happy to oblige, and thus our partnership was born. 

Is the Smooth & Slim for everyone? Probably not. There are lots of players who like a raw, edgy distortion, and quite a few who are perfectly happy with the clipping a stomp box delivers through a Twin. Hey, whatever's cool. On the other hand, if you're a player who likes the smooth, sweet sustain featured on Abraxas, or if you lust for a smoking Dumble Overdrive Special, to take just two examples, you owe it yourself to try out the Smooth & Slim. Not many of us can afford Dumbles, but there are quite a few decent high gain amps out there that the average picker can latch on to for not too much green, and, with the addition of the Smooth & Slim, he/she could find him/herself in Tone Heaven quite inexpensively! Okay, so they won't sound as good as a Dumble right off the shelf... what's a tone prospector to do? 

Most cats start by forking over $75 a pop for some really high quality power tubes. Still not there? Pickups might be next - you can replace them out at about $100 each and hope you pick the right one within the first two or three tries. Then, stomp boxes are yet another choice. And these are the cheap fixes, as anyone who has seen the prices lately in Vintage Guitar Magazine will tell you. I went down this path myself for many years and many dollars. (Actually, I'm still a sucker for anything that might improve my tone, budget permitting.) Truth is, none of it made as much difference as putting the Smooth & Slim in front of my amp. You might be surprised at just how smooth and singing your amp might sound with one of these gizmos, too. 

After testing the original Smooth & Slim design with several amps, we've added some final touches and hand-built the first units, which will be ready to be offered for sale soon. We will make an announcement on some of the newsgroups popular amongst guitarists and we'll be gald to take orders at that time. If you have any questions in the meantime, just holler: Gil's email address is shown at the bottom of the Home Page, and mine appears below. We're excited and proud to be able to bring to all of you a product both Gil and I believe in!


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## sct13

It is an entirely stock, Diode rectified 50watt. (The tag says JTM45 MkII) 

But I am pretty sure is a 68/69 Plexi Panel 50watt. 

Its not switchable, but I have a JTM45 build that I want to make switchable. 

It is a split cathode on V1 

Why what do you see? 

Here is a better pic...

OP; Sorry don't mean to hijack your thread.


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## jack daniels

sct13 said:


> It is an entirely stock, Diode rectified 50watt. (The tag says JTM45 MkII)
> 
> But I am pretty sure is a 68/69 Plexi Panel 50watt.
> 
> Its not switchable, but I have a JTM45 build that I want to make switchable.
> 
> It is a split cathode on V1
> 
> Why what do you see?
> 
> Here is a better pic...
> 
> OP; Sorry don't mean to hijack your thread.



I'm seeing a split cathode circuit minus the 2K7 resistor in parallel with the .68uF cap. The split cathode circuit requires a jumper cable for channel interaction Versus a shared cathode circuit w/no need for a jumper cable for channel interaction.


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## jack daniels

My Mouradian JTM45/50 has the shared cathode config.


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## sct13

I see what your seeing, That resistor is under that .68 uf Cap,


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## jack daniels

sct13 said:


> I see what your seeing, That resistor is under that .68 uf Cap,



Then your amp is wired split cathode which means your Vol I and Vol II shouldn't interact UNLESS you have a jumper cable across said channels. Conversely, with a Bassman, Super Bass, JTM45, JTM45/100 you don't need a jumper cable for Vol I and Vol II to interact. FWIW buy yourself an Ayan S&S passive lo pass filter. You won't regret it as you'll get rid of that "flub" that you spoke of. Great little units, I bought one when I had my Mesa Boogie Mark I reissue amp.


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## SmokeyDopey

FutureProf88 said:


> Angus ran his on ~5-6.



Well, I would say it _is_ wide open there... You do have more room: up to 10. But but at that point (5 or 6), the output tubes are already singing like the fat lady.
No need to go all the way to 10 for it to be wide open, at least what I think. 10 is cool for when the room is all funked up, ya know?


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## SmokeyDopey

10 is the sound of Satan clearing his throat. Throw a fuzz in there if you want him to yell.


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## jack daniels

SmokeyDopey said:


> 10 is the sound of Satan clearing his throat. Throw a fuzz in there if you want him to yell.



[ame]http://www.youtube.com/watch?v=rXH_12QWWg8[/ame]


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## Joshabr1

I'm getting to we're I like my superbass on 9. It has a 100pf bright cap (favorite value) 5k is just to much for me. But when u get up past 7 the amps w bright caps will gain low end from the cap being bypassed more and more. They sound the best around 8 really. Loud as your ex mother-in-law.


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## Joshabr1

When u get em turned up to 8 or so you can really ride your volume and tone controls. You can go from clean to head ripping with the touch of your hand


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## Metroman

For me channel jumping is just another way to get a great sound and more versatility. Its 1 of Many great sounds to be had from most any nice 4 holer.

Ive mainly been a Dual Showman guy since 72 ( Most I like though use a Marshall... or have ) and got a Metro Amps GMP45 about 9 months ago and now I can even hardly play the Fender, and the Fender is a great amp. Its been modded by Richie Hall of Hall Amplification to have an ODS mod, PPIMV Blackfaced. All new caps/NOS tubes ect. 1 of if not the best sounding Fender Im ive ever heard.

But for me Channel jumping is a great tone generator. Channel Jumping I can still get Cleans that Beat the crap out of My 69 Dual Showman.

Ive also observed 0000 Noise/Mud with my amp... Even at 10. I usually run my amp from 6-10 and control everything with the Guitar volume Knob. I got that from Martin Barre ( Tull ) back in the early 70's and have done it ever since.

I also like Pot Tapers on my guitars/amps to come on Slowly from 0 on up. I don't like a control that has the guitar/amp Loud at 1. Useless for me. The Metro also has a Smooth Slow Taper.

I also have Really Good Low Microphonic/Noise Preamp/Power tubes.

I use a Mullard 10M Gold Pin in Both V1 x V2 and a 56 Mullard Longplate in V3 x Mullard Fat Base x 1961 GZ35/5AR4.

If a 10M is up to Spec ect. You'll Never find a tube that is more quiet.

It also has the Sound of the Old 50's Longplate 6L13/12AX7 but is DEAD QUIET and Very Very Durable. They Originally had 2 Years or 10,000 Hours Guarantee from the Factory .

I get 00000 Mud//Noise on 10. None. If I did Id find a way to get rid of it or get rid of the amp.


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## GIBSON67

I always liked to jump my 1987 channels, but I had a PPIMV so I would run the bright channel on 10 and normal channel on 5-6 for added bass but no mud. I could still roll back my volume to get good cleans. 

Now, I've been tinkering with the OWM, and I have tried the shared cathode for V1, and I like it. Definietly has more Jimi sounds that way. But I haven't settled on my values, yet. So far I like...1500/220 on V1a, and 1500/0.68 on V1b with SB tone stack and bright cap of 500pf. 

It would be fun to set up two separate valves with cascaded inputs blended together...


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## jack daniels

Joshabr1 said:


> On shared cathode amps jumping makes them muddy to me. I think it matters much what ur set up is. If u have 2 basketweaves shared cathode and pafs jumping wouldn't make sense. If u had to cabs full of 75s and a strat jumping would be a good option.



Josh, with a Fender Tweed Bassman, Marshall Superbass, Marshall JTM45, and Marshall JTM45/100 you Do Not need to jumper as they're already internally jumped with a shared cathode connection (pin 8 to pin 3) of V1.


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## AlvisX

Shared cathode 
Jumped channels
470pf brite cap
vol 5
vol 5
bass 4
mid 7 
treb 5
pres 6
You'll win Grammys with that sh8T......


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## jack daniels

AlvisX said:


> Shared cathode
> Jumped channels
> 470pf brite cap
> vol 5
> vol 5
> bass 4
> mid 7
> treb 5
> pres 6
> You'll win Grammys with that sh8T......



Jumped channels (internally)


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## AlvisX

jack daniels said:


> Jumped channels (internally)




Not for me , but if that works for you cool


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## Clammy

jack daniels said:


> Josh, with a Fender Tweed Bassman, Marshall Superbass, Marshall JTM45, and Marshall JTM45/100 you Do Not need to jumper as they're already internally jumped with a shared cathode connection (pin 8 to pin 3) of V1.



Are you saying that the channels interact the same way whether or not you use a jumper cable? Because if you are, you're incorrect (for Marshall Super Basses, anyway). I have 3 early 70s, unmodded , Super Bass amps, and there is a VERY noticeable difference in the way the channel volumes interact depending on if I use a jumper cable or not. Without the cable, the unplugged channel volume has almost no impact at all.

Cheers!


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## FutureProf88

Clammy said:


> Are you saying that the channels interact the same way whether or not you use a jumper cable? Because if you are, you're incorrect (for Marshall Super Basses, anyway). I have 3 early 70s, unmodded , Super Bass amps, and there is a VERY noticeable difference in the way the channel volumes interact depending on if I use a jumper cable or not. Without the cable, the unplugged channel volume has almost no impact at all.
> 
> Cheers!



The cable makes it sound different (much more apparent) but without the cable it does make a difference. I wouldn't go so far as to say internally jumped because you aren't getting as much of the effect from the other channel, but if I plug in to the top left on my 45/100 clone and then turn the bass channel up I can tell that there is a thickening of Channel I.


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## jack daniels

Clammy said:


> Are you saying that the channels interact the same way whether or not you use a jumper cable? Because if you are, you're incorrect (for Marshall Super Basses, anyway). I have 3 early 70s, unmodded , Super Bass amps, and there is a VERY noticeable difference in the way the channel volumes interact depending on if I use a jumper cable or not. Without the cable, the unplugged channel volume has almost no impact at all.
> 
> Cheers!



Why do you think they call it a shared cathode configuration? OR Talk to the hand 'cause the face don't give a damn.


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## GIBSON67

Shared cathode configuration is just biasing the V1 triode using only one set of components. I don't see how this blends the channels together?


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## mickeydg5

Signal at the control grid causes current and voltage fluctuation at the plate as well as the cathode. Since both cathodes are connected those fluctuations are passed to the other triode. The flucuations mimic signal. Tubes can be driven via the cathode.
In this circuit the affect is small but present.

However, the two volume controls connected to each other through resistors or whatever prior to V2 have more affect. Also keep in mind that the potentiometers are in parallel. You guys know what parallel does with resistance.


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## Joshabr1

Just cause an amp is shared cathode don't have anything to do with jumping. U still have to jump channels on a jtm 45 pre amp to get the effect of jumping.


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## mickeydg5

Definitely. If the full on affect of both channels mixed is wanted then a jumper at the inputs is required.


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## stalefish

FutureProf88 said:


> The cable makes it sound different (much more apparent) but without the cable it does make a difference. I wouldn't go so far as to say internally jumped because you aren't getting as much of the effect from the other channel, but if I plug in to the top left on my 45/100 clone and then turn the bass channel up I can tell that there is a thickening of Channel I.



Agreed. On mine, I get a slight change when mixing the vol knobs without physically jumping, but there is a change. When I add the jumper, the change is way more pronounced. Then I scrap it all because I like high input 1 by itself.


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## sct13

I am still stuck on the shared cathode and split cathode thing, and the statement that the two channels do not interact unless its a certain split/shared configuration. 

The 68 plexi interacts subtly, I can add a bit of bass with te normal channel if I am plugged in to only the bright. 

Its not the same as jumping.....


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## Joshabr1

If ur not plugged in thru the normal input then u r not getting the effect of that channel. That is not theory that is factual. Yes there may be a touch of bleed but its very subtle. All my superleads and superbass amps are shared cathode. I turn the normal vol from 1 to 10 and can't hear that much of any difference at all. I only play plugged in thru the bright channel high input.


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## mickeydg5

With a shared cathode V1 the unused channel volume control will have more affect when the used channel volume control is set lower. If the used channel volume is set high the other control will have lesser to no affect.

Just like most amplifier volume controls, the tone changes when set lower as compared to higher or maxed. The two volume controls are working together or against each other depending on how you want to look at it. Like I mentioned earlier the two volume potentiometers are in parallel.


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## Joshabr1

Thanks Micky I didn't know that. That's probably why I don't hear much of a difference. I play them on 9 everytime I turn em on. So the bright channel would be dominating. I never looked at it the way u put it there. I notice people's comments. You are sharp on em.


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## jack daniels

Two potentiometers in parallel (or halved resistance) Reduced volume or more volume? Pardon me Mickeydg5 but I'm not having a light bulb moment here, would you please splain the impotence or is that Splawn the impotence? (just kidding!)


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## sct13

mickeydg5 said:


> With a shared cathode V1 the unused channel volume control will have more affect when the used channel volume control is set lower. If the used channel volume is set high the other control will have lesser to no affect.
> 
> Just like most amplifier volume controls, the tone changes when set lower as compared to higher or maxed. The two volume controls are working together or against each other depending on how you want to look at it. Like I mentioned earlier the two volume potentiometers are in parallel.



you did mention that, I remember. 

Exactly what then affects the channel differences. I ask because I have a bit of a problem with a Marshall style circuit. I need a clearer understanding of what makes the two channels different.


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## Joshabr1

sct13 said:


> you did mention that, I remember.
> 
> Exactly what then affects the channel differences. I ask because I have a bit of a problem with a Marshall style circuit. I need a clearer understanding of what makes the two channels different.



Bright cap on channel 1 pot and mixer cap on the 470k resister also the first coupler on lead circuit is 2n2 instead of 22n which also gives a brighter snappier responce. On a split cathode the normal channel is 820/330uf cap and bright channel is 2k7/.068 cap. I like shared cathode 22n for both channels and output with 100pf bight cap 47k on 8ohm neg feedback. Good thick and creamy no jumping nessecery


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## Joshabr1

On shared cathode amps both channels run thru the 820ohm/330 set up.


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## mickeydg5

jack daniels said:


> Two potentiometers in parallel (or halved resistance) Reduced volume or more volume? Pardon me Mickeydg5 but I'm not having a light bulb moment here, would you please splain the impotence or is that Splawn the impotence? (just kidding!)


Look at the two volume potentiometers. Each is connected to ground and their wipers are connected to a 470k and then to a common point before V2. That places them in parallel. The common tie point provides signal path to and from both potentiometers.

Now look at the potentiometers. See how the other potentiometer will influence signal to ground, like a second volume control.

The affect is more drastic in a Fender type amplifier because of the use of 270k and not the larger value 470k.


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## sct13

Thank you 

that helps. 

The amp I am working on does not have these values. So I guess that's where it parts ways from Marshall.


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## mickeydg5

Also to note is if using one input, the amplifier should achieve maximum gain/volume with the unused VOLUME control at about 8. Above or below that 8 area will decrease signal. That is due to the LOG/Audio potentiometer.


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## mickeydg5

sct13 said:


> Thank you
> 
> that helps.
> 
> The amp I am working on does not have these values. So I guess that's where it parts ways from Marshall.


If you are talking about that Traynor you do not want to set the unused volume control at zero. That will kill a lot of signal. The mixing resistors are only 100k in there.
Again those are supposedly LOG/Audio potentiometers so set the unused volume control at about 8 for maximum signal.


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## sct13

right 100k 

the problem is not related to this post, only inasmuch as what separates the two channels. Ch I sounds pretty good, its crisp and clean whereas ch II is way too trebly, its impossible to even turn it to 3, its very bad. 

turning it up past 8 it will sound somewhat better. But something is out of whack. 

If you want you can reply in that thread asking about caps, I don't want to hijack this one.


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## jack daniels

mickeydg5 said:


> Look at the two volume potentiometers. Each is connected to ground and their wipers are connected to a 470k and then to a common point before V2. That places them in parallel. The common tie point provides signal path to and from both potentiometers.
> 
> Now look at the potentiometers. See how the other potentiometer will influence signal to ground, like a second volume control.
> 
> The affect is more drastic in a Fender type amplifier because of the use of 270k and not the larger value 470k.



Thanks Mickey! I especially appreciate the notes in the bottom left hand corner of said schematic.


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## mickeydg5

Those are not my notes. I think it was copied from a bing search and pasted. It was redone and clearer. The notes are a bonus.


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## jack daniels

Mickey, I remember my 90' Fender Bassman RI amp manual talking about "not needing to jumper" because of the circuitry (shared cathode) and the volume controls being interactive w/o said jumper cable. This was linked to the shared cathode and Marshall's with that configuration in another article somewhere online, and that's why I had this premise in my head.


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## mickeydg5

Well that is all true but there is not much signal to amplify at that shared cathode setup.
If you want real parallel gain/volume mix control then the jumper cable gives maximum benefits.


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## jack daniels

mickeydg5 said:


> Well that is all true but there is not much signal to amplify at that shared cathode setup.
> If you want real parallel gain/volume mix control then the jumper cable gives maximum benefits.



As per usual, more half truths from manufacturers.


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## chet rippington

also, you can insert an effect box (delay etc) in the jumpering process and then dial in the amount using the second volume control.


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## IronMaidenNutter

I like jumping... Vol 1 on 8, Vol 2 on 6. 

I love the pure aggression it makes. It feels so powerful, like the speakers are about the explode...


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## dreyn77

they do. 
it's terrible for your amp. 

there's NO need to do it today. 

you'd just play the seymour duncan pickup version. it's all there in the pickup. 
that's just 1 example. 
you could just use the bigger magnet speaker. 

don't ruin the one thing that can get ruined. the amp. 

it's an OLD technique and seymour has made a career out of makeing pickups do those sound without puting in the link. 

that's like saying you're going to put wooden wheels on your car so you can hear the creeking from the wood when you drive around corners in the road. 

so the ONLY people who have the option to do this linking are the people who run VINTAGE guitars and are sick of the perfect tone from their setup. 

EVERYONE else has some form of linking tone to their setup already without linking the amp. 
90% of pickups are already putting the linked tone into the sound.


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## IronMaidenNutter

So you're saying jumping the channels is not needed and it will destroy my amp?

I don't really want to change the pickups from my Les Paul... you pay enough for an R8 and it sounds great with what it has!


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## GIBSON67

Jumping channels is fine and won't hurt your Marshall. 

There are many posts to read, but most people have put Dreyn77 on ignore for a reason...especially since he is allowed to post garbage and we can't stop it...


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## ampmadscientist

Jodyzuza said:


> Is there any preference on jumping the channels, I.e. Which inputs to jump? Or how about using a Y cable of sorts?
> This is my first plexi so trying to learn how to use it lol



Jumping the channels together is not really a good solution.
To get what you really want, you need to modify it.
But the modification is not complicated...it's a relatively small change.

This change is the basis of 2204 amplifier.
A Plexi, with 1 added gain stage.


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## neikeel

If you want to blend the channels in different combinations (without jumping, modding etc) a really good solution is a Y-cable.

It will not damage your amp, but neither will jumpering (what is Dreyn on?). Jumpering and Y cables give a little more gain but not as much as a cascade which involves modding, something that so many people did to their NMVs, realised it was not as versatile and put them back to stock!


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## strato2009

If using pedals with JMP 4 input head, is the lower input of bright or normal channel recommended?

Is there any difference in jumping vs y cable in terms of sound?


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## dreyn77

I'm SO sick of people who think EVERYONE thinks like them and people who know something they don't get catarorized as being on DRUGS. (as children who view the world might use such EXTREME methods to deal with the older wiser person) 

I've told you before, MARSHALL put in the 'bright sound' capacitor so THEY don't agree with YOU. 

it's NOT MY AMP! it's NOTHING TO DO WITH ME! 

the pickups make the bright sound the speakers makes the bright sound the AMP makes the bright sound BUT YOU want to link to get the bass sound BUT THEY installed the brightness MOD. 

link if you like. nothing to do with me and weeds.


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## dreyn77

Zakk WYLDE has the bassy type of sound from these things. 

well guess what?
He modded the pickups, he modded the speakers, he modded the pedals, he modded the AMP. 

end of the truth, game over!


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## Metroman

_I don't have a 100 watter but I have a Metro GMP45 and jump the channels with a Mogami Y chord._


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## levelx43

Nathan Brown said:


> *I've jumped the channels only on one amp, a 1976 MV Fender Bassman 10.* It sounded like a chipette getting some during mating season but damn was it loud.



Uh Nathan...did you forget about this post on 6/9/15?
I find it hard to beleive that you of all people could forget playing a JMP!

QUOTE=Nathan Brown;1341830]Yes Redstone, I played a four holer. It was a 1971 or 72 JMP with the block indicator light, and the early switches. And when I jumped the channels with a patch cable, holy ****nicks it sounded ****ing great. I was playing a '57 Reissue Stratocaster in the neck position, and it did have a lot of low end but I was playing through a 1960A cab too. I played with the settings and it sounded good with her bass at 5.5, Treble at 7 and mids at 4. Loudness 1 at 3, and loudness 2 at 2.2[/QUOTE]


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