# Master Volume Pedal?



## nwoof2012 (Jun 28, 2019)

A while ago I tried out the Marshall Studio Vintage. I like to use an overdrive tone, and since the Studio Vintage is based on a JMP Superlead 100W 1959SLP, which has no master volume, I can’t get the Plexi crunch at a volume suitable for playing in a guitar store. Does anyone know of a volume pedal currently in production that I can use in the FX Loop as a master volume (I’m looking for one controlled by a turn potentiometer, since an expression-controlled volume pedal would be too easy to change massively). I’m okay with a pre-phase inverter Master Volume setup.


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## Budda (May 29, 2007)

You are probably better off with an attenuator.

But the real "easy" way is an overdrive pedal. I suggest the fulltone ocd or dirty little secret.


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## Granny Gremlin (Jun 3, 2016)

Any volume pedal will work in the fx loop but that wont necessarily be very much like a master volume. Also you wont get the power tube ( or the last few preamp tubes) driving ng very hard that way so dont think it’ll do what you expect.


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## Guncho (Jun 16, 2015)

If you could just stick a volume pedal in an fx loop to get power tube overdrive at bedroom levels, there would be no need for attenuators.


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## nwoof2012 (Jun 28, 2019)

Budda said:


> You are probably better off with an attenuator.
> 
> But the real "easy" way is an overdrive pedal. I suggest the fulltone ocd or dirty little secret.


Before trying out the amp, I asked if the guitar store had an attenuator, and they said that they don't have it on hand for testing out an amp.


Granny Gremlin said:


> Any volume pedal will work in the fx loop but that wont necessarily be very much like a master volume. Also you wont get the power tube ( or the last few preamp tubes) driving ng very hard that way so dont think it’ll do what you expect.


Why won't it be very much like a master volume?


Guncho said:


> If you could just stick a volume pedal in an fx loop to get power tube overdrive at bedroom levels, there would be no need for attenuators.


It's a common misconception that the Plexi's overdrive is pure Power Tube. The Plexi's overdrive is actually preamp tube overdrive. It's like if you took an amplifier with crunch, and bypassed the master volume circuitry. Go look up a schematic of a 1959SLP.


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## troyhead (May 23, 2014)

Granny Gremlin said:


> Any volume pedal will work in the fx loop but that wont necessarily be very much like a master volume.





nwoof2012 said:


> Why won't it be very much like a master volume?


The FX loop is usually between the preamp and the power amp, so a volume pedal in the FX loop will be *before* the power amp. However, with a Plexi amp, much of the overdrive is actually from the power section. So a volume pedal in the FX loop will just reduce the signal so much that the power tubes will not be driven hard enough to produce most of the overdrive. 

Is your concern just about trying the amp in the store? Do they not have a separate room you could use to try the amp? If not and they want to make the sale, just go when they aren’t busy and crank it up (and hope no guitars fall off the wall).


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## Guncho (Jun 16, 2015)

Yeah if what you're looking for is preamp gain than sticking a volume pedal in the effects loop should act as a master volume.

Heck stick an EQ pedal with a volume slider in there.


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## Budda (May 29, 2007)

Heck just buy one of the many marshall in a box pedals out there and buy your favourite clean amp to go with it.


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## nwoof2012 (Jun 28, 2019)

troyhead said:


> The FX loop is usually between the preamp and the power amp, so a volume pedal in the FX loop will be *before* the power amp. However, with a Plexi amp, much of the overdrive is actually from the power section. So a volume pedal in the FX loop will just reduce the signal so much that the power tubes will not be driven hard enough to produce most of the overdrive.
> Is your concern just about trying the amp in the store? Do they not have a separate room you could use to try the amp? If not and they want to make the sale, just go when they aren’t busy and crank it up (and hope no guitars fall off the wall).


Did you see me say the Plexi uses more preamp overdrive than you probably think? In the schematics of JMP and JTM amps, in JTM, there’s a preamp gain stage, and the JMP uses two.
I also want a way to get overdrive from the amp without blasting my hearing (or driving the neighbours to call the cops). I’ve also designed a schematic and PCB for the guitar pedal I’m looking for.


Guncho said:


> Yeah if what you're looking for is preamp gain than sticking a volume pedal in the effects loop should act as a master volume.
> 
> Heck stick an EQ pedal with a volume slider in there.


My sound doesn’t rely much on power tube saturation. Preamp overdrive can do all I need. I also have a BOSS GE-7, but I already use it for something else: I use it to create a lead tone different from my rhythm tone. I also posted earlier in this reply saying that I designed a guitar pedal to do what I’m looking for.


Budda said:


> Heck just buy one of the many marshall in a box pedals out there and buy your favourite clean amp to go with it.


My goal is to get quality amp distortion and the volume and response of a tube amp. I like to have crunch in an amp, which would be hard to get with a clean amp at low volume levels.


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## Budda (May 29, 2007)

Ok but the "quality amp distortion" comes with a volume you dont want, and you dont want to go the correct route to get it. The correct route is a two notes torpedo etc.

Sure some of the plexi sound is from the preamp, but *most of it* is from cranking the thing. I play a jcm800 2203 on 7, I know what Im talking about.

It is dead easy to get crunch from a clean amp at low volumes - *use a pedal.* Amp distortion is not and has never been a low volume thing, unless you are using a 5150.

Do you want the best sound for your volume constraint, or do you absolutely have to stick to your "the amp must do all the work" values? Seems to me it's the latter.


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## nwoof2012 (Jun 28, 2019)

Budda said:


> Ok but the "quality amp distortion" comes with a volume you dont want, and you dont want to go the correct route to get it. The correct route is a two notes torpedo etc.
> 
> Sure some of the plexi sound is from the preamp, but *most of it* is from cranking the thing. I play a jcm800 2203 on 7, I know what Im talking about.
> 
> ...


I like to set an amp at low gain, then boost it in to medium gain.


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## Budda (May 29, 2007)

nwoof2012 said:


> I like to set an amp at low gain, then boost it in to medium gain.


Then you can still use a pedal, since you also need it to be quiet.

Low gain is more a pushed clean, less an overdrive.


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## Granny Gremlin (Jun 3, 2016)

nwoof2012 said:


> Why won't it be very much like a master volume?


Because it's not a master volume, you're just kludging it. Depending on the circuit (where the fx loop is) it could be pretty close. I didn't say it won't be, just not necessarily. Not a bad idea and it will work to give you a general idea, especially of the preamp sound, which is important in the purchase decision.




nwoof2012 said:


> It's a common misconception that the Plexi's overdrive is pure Power Tube. The Plexi's overdrive is actually preamp tube overdrive. It's like if you took an amplifier with crunch, and bypassed the master volume circuitry. Go look up a schematic of a 1959SLP.


Don't put words in people's mouths. Of course it's not ALL power tube, but it IS _partially_ power tube. There's a reason why various methods of getting 'that sound' at lower volumes (from master volumes to pedals) have not been satisfactory to folks and we invented attenuators (see also the popularity of the 18 watt Marshall clone - and yes, I know this is an 18 watt Marshall we are talking about here, which supports my point - imagine how much harder it is with a regular 50/100 watter).



troyhead said:


> The FX loop is usually between the preamp and the power amp, so a volume pedal in the FX loop will be *before* the power amp.


We can be more specific than that, and it will be relevant to the first point above. The Plexi OD sound is caused by all the tubes being driven (so lets not argue about how much of that is attributable to the power section, because irrelevant; it is a significant contributor, as is the preamp... but there is more to an amp than just power and preamp). The FX loop may not just be before the power section, it is also (like for sure) before the phase inverter (there is a reason PPIMV mods are a thing), as well as possibly (I have not looked at the schem) a number of other tubes (e.g. post fx loop buffer, if not solid state, or just a PI driver stage - it does not have reverb, but as a further example, the mixer stage after the reverb recovery would likely be after the fx loop as well etc).

The point is this will give some indication of the voicing of the amp, but similar to (eg if the OP were looking at the head vs the combo - dunno if he said above) using a 1x10 in the store vs the 4x12 you have at home and would (eg) gig with - it will not have all the meat of a truly dimed plexi, but it will tell you something. Not sure if it tells you enuf, but something.


.... lastly, don't these things have a 20/5 watt switch on the back (just checked out the Marshall product page or was I looking at the wrong model)? That would be the easiest thing - you should be able to dime it in store at the 5 watt setting (esp if you go at non-peak time as recommended above and/or use one of the booths assuming your location has them - bring ear protection though). This will still not sound the same as the same amp dimed in 20 watt mode (how different depends on how they did that - assuming single ended class a triode vs PP class AB pentode that could be a bg diff) but it will be a lot closer - as close as you'll get without a power soak (and even a power soak isn't exactly the same due to not driving the speakers as hard - do not underestimate the contribution to 'the Marshall sound' of a broken up 4x12 - that takes some power).


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## nwoof2012 (Jun 28, 2019)

Granny Gremlin said:


> Because it's not a master volume, you're just kludging it. Depending on the circuit (where the fx loop is) it could be pretty close. I didn't say it won't be, just not necessarily. Not a bad idea and it will work to give you a general idea, especially of the preamp sound, which is important in the purchase decision.
> 
> 
> 
> ...


I don’t have a problem with no power tube saturation, so a master volume will do the trick for me.
I also know that when you crank the master volume, you’ll get power tube distortion, and since the Plexi’s master volume is fixed at 10, there will be power tube distortion.


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## gproud (Mar 2, 2006)

I suspect the JCM800 Studio amp would be more to your liking. 

Sent from my LM-Q710.FGN using Tapatalk


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## nwoof2012 (Jun 28, 2019)

gproud said:


> I suspect the JCM800 Studio amp would be more to your liking.
> 
> Sent from my LM-Q710.FGN using Tapatalk


I’m trying to avoid the Studio Classic, because the bright cap has been known to make it impossible to sound good at practice volumes.


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## Budda (May 29, 2007)

Why not actually try it first?

Presence to 0.


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## nwoof2012 (Jun 28, 2019)

Budda said:


> Why not actually try it first?
> 
> Presence to 0.


The problem is not too much high frequencies; my tone relies heavily on mid frequencies, so having no mid frequencies can cause problem for me.


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## Budda (May 29, 2007)

nwoof2012 said:


> The problem is not too much high frequencies; my tone relies heavily on mid frequencies, so having no mid frequencies can cause problem for me.


You can set the mids to 0 and an old marshall will still be mid heavy.

Go play some amps.


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## nwoof2012 (Jun 28, 2019)

Budda said:


> You can set the mids to 0 and an old marshall will still be mid heavy.
> 
> Go play some amps.


Today, I tried a Marshall Studio Vintage with a BOSS BD-2 in front. It was a painful experience, since even with the power on low and volume quite low, it is too easy to make the Studio Vintage painfully loud.
I've also heard the Studio Classic would have the same problem.
The bright cap cuts out lower frequencies and keeps higher frequencies, which is why people like to crank a JCM800.
I've played Marshall Amps. I've tried the DSL40CR, the Marshall Origin 50H, the Marshall SV20C, the DSL1CR, the DSL15C, the DSL20H, the DSL5C, and that's all I can recall right now.


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## Granny Gremlin (Jun 3, 2016)

nwoof2012 said:


> I don’t have a problem with no power tube saturation, so a master volume will do the trick for me.


Then get a pedal ( plenty of Marshall preamp inspired ODs and Distortions out there, including ones by Marshall - out of prod but clones exist) and a cleanish pedal platform amp. ... and an eq pedal or otherwise since you like your mids etc just so. If you're not into power tube OD then youre wasting a lot of time and money. This would also be easier to try in store before buying.


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## nwoof2012 (Jun 28, 2019)

Granny Gremlin said:


> Then get a pedal ( plenty of Marshall preamp inspired ODs and Distortions out there, including ones by Marshall - out of prod but clones exist) and a cleanish pedal platform amp. ... and an eq pedal or otherwise since you like your mids etc just so. If you're not into power tube OD then youre wasting a lot of time and money. This would also be easier to try in store before buying.


I currently have a TC Electronic Dark Matter, which turns my crappy practice amp into a Plexi on 11.
An amp I can get and tube-like overdrive and volume levels out of is the BOSS Katana. I’m thinking of getting a BOSS Katana Head and a Marshall 4x12. I’ve tried the BOSS Katana Head through a Mesa/Boogie 4x12 with Celestion Vintage 30s. The Marshall 4x12 that I’m thinking of getting uses Celestion G12 speakers. That Marshall 4x12; I’ve used a Marshall Origin 50 Head through it, and I feel it’ll be suitable for me.


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## Guncho (Jun 16, 2015)

nwoof2012 said:


> I don’t have a problem with no power tube saturation, so a master volume will do the trick for me.
> I also know that when you crank the master volume, you’ll get power tube distortion, and since the Plexi’s master volume is fixed at 10, there will be power tube distortion.


No there won't be unless you crank the amp up loud.


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## nwoof2012 (Jun 28, 2019)

Guncho said:


> No there won't be unless you crank the amp up loud.


I was saying that having no master volume is like having a master volume on ten—in order to eliminate power tube saturation, you have to sacrifice all gain.


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