Is diming a master volume the same as a non-master?

[d.rhoads]

This is probably asked all the time. It seems as though it would be, but I just wanted to make sure...

 

[oldschoolguy]

That's how I understand it. Maxing the master takes it out of the circuit. I have several amps like this. Last night i dimed the master in my Kingsley Keep and it sounded fuller than with it in use, but the difference won't keep me from using the master when I want. So,my guess is, tho, that the very process of wiring in a master to begin with may cause a difference in the outcome of the circuit type without master.

 

[Don A]

I believe it depends on the type of master. The Metro Amp Lar/Mar PPIV that I put in my Vibrolux Reverb is electronically similar to the 220k resistors that it replaced when it's dimed.

It sounds the same, dimed, as it did stock.

 

[Tone_Terrific]

I believe it depends on the type of master. .

Back in the 70's amps would just get a 'master' pot installed on the signal line and it was not quite the same thing as NMV.
For those who think preamp distortion is a good thing...try that.
It takes some work to make tubes sound good.

 

[DT7]

If you're talking a Marshall 1959/1987 vs 2203/2204, the answer is no...the 2203/2204 Master Volume does not remove itself from the circuit when dimed.

The answer depends on the amp and mod (if there is a mod). You'd have to be specific about the amp/mod you're talking about.

 

[freaksho]

https://www.thegearpage.net/board/index.php?threads/1140802

 

[upfrontguitars]

In general, no. Master Volume controls can be configured several different ways, but in general they are allowing the amp to create distortion by overloading the preamp while controlling overall loudness to a reasonable level. Diming a non-master amp typically creates distortion in the power amp section, which tends to be warmer, creamier and less fizzy. However, the volume levels tend to be extremely high, hence the renewed interest in lower powered amplifiers and various attenuators like the Hot Plate and Rivera RockCrusher. "Cascading gain" amps like the Mesa Boogie are essentially master volume amps too, just with better marketing. While purists may prefer a cranked low power amp, there is nothing "bad" about a well executed MV amp. In general it's a tighter, more modern sound.

 

[VaughnC]

Depends on the circuit & ears. If you want to pick nits, with a master pot up full, the wiper is still in contact with the end of the pot's resistor element so its not exactly the same as a direct connection. Also, the extra wiring required to wire the pot into the circuit may have some effect due to the stray capacitance difference. Some may hear a difference, some may not.

 

[GibsonLives]

The good news is that, the more time you spend with your amp dimed, the worse your ears will become, and the less difference you'll notice
Steve

 

[epluribus]

If you're talking a Marshall 1959/1987 vs 2203/2204, the answer is no...the 2203/2204 Master Volume does not remove itself from the circuit when dimed.

The answer depends on the amp and mod (if there is a mod). You'd have to be specific about the amp/mod you're talking about.

Yup. Depending on the MV circuit, they can alter the impedance structure and very audibly change the sound and dynamics even when dimed. Well-designed MV, OTOH, does indeed remove itself from the circuit. However, that said, some people maintain that simply having the stuff inserted in the wiring at all makes a noticeable difference. Can't prove that claim on a 'scope, but having done it on my workbench I'd have to disagree...good MV acts like it isn't there when it's dimed. Sadly, that's not all MV.

--Ray

 

[sepulchre]

The good news is that, the more time you spend with your amp dimed, the worse your ears will become, and the less difference you'll notice
Steve

Good one, Steve! Got a laugh out that.

I know I'm getting here a little late (a month) but...

First, it occurred to me that a MV could be rigged with a switch on it that actually did bypass it when turned all the up. Crank it until it clicks and voila, no MV! But I've never seen or heard of anything like that on a commercial amp, or any other for that matter. I read above that some amps effectively take the MV out of the circuit when dimed - how, barring a switch, would one eliminate the connection, albeit resistive, to ground through the pot?

One of my favorite amp designers, Ken Fischer (Trainwreck), said that master volumes effect the responsiveness of an amp. The term he used was amps without them are "quicker".

I tend to agree with Ray; if a MV is well designed it should pretty much disappear when dimed. But Mr. Fischer's amps sound so good that I have to take his words into consideration, at least. Ears are very subjective, as Steve so aptly put.

But, just for grins, maybe I'll try a true bypass switch on a master volume. My ears are not the best, after all my youth put them through, but who knows?

Ken

 

[Nelson89]

The only amp i really have to test this on is my AC15HW1 which has a NMV switch to defeat the master altogether, it sounds slightly different (fuller) with the NMV switch engaged compared to the master dimed, but not different enough to really get bogged down with it.

 

[sepulchre]

I didn't realize that AC15s had such a switch. Goes to show how many Voxes I've worked on . . . few. Okay, just one; my old Super Beatle. But that was many years ago.

 

[Nelson89]

I didn't realize that AC15s had such a switch. Goes to show how many Voxes I've worked on . . . few. Okay, just one; my old Super Beatle. But that was many years ago.

Yeh, i think they popped up on the latest handwired ones, they've got defeatable master volume, half power switch and "hot" switch which defeats the EQ section. Pretty cool features if i do say so myself (if you're into simple amp circuits that is).

 

[sepulchre]

Gotta say, Vox is making some nice amps.

 

[Phletch]

OK, I'm lost here, so, please bear with me. I have a Mesa Mini Rectifier. It's got "gain" which, as I understand, controls the pre-amp signal (pre-amp volume) to the 12AX7s, right? And the "volume" controls the main amp EL84s, right? So how does that work if I dime the volume, then what? Is that out of the circuit? Is that a "master volume?"

For what it's worth I try to get the sound I like by driving the "volume" as high as possible to work the mains, and push the "gain" only as much as necessary to get the right amount of OD from the pre-amp with the least amount of "fuzz." I like a nice, round, creamy OD, and that seems to work best, rather than the opposite (high gain, low volume) which tends to be more saturated, less warm. It seems to work that way, to my ears anyway, and that's the way I've always approached amps with separate gain and volume controls. Am I on the right page and just don't know it or know why?

 

[geek-mo]

The only amp i really have to test this on is my AC15HW1 which has a NMV switch to defeat the master altogether, it sounds slightly different (fuller) with the NMV switch engaged compared to the master dimed, but not different enough to really get bogged down with it.

I have the same amp and, of all the cool features that it has, this has ended up being my favorite. When I take the master volume out of the circuit, it sounds much bigger to me. However, it is nice to have MV when you need it, so it is really the best of both worlds.

 

[Nelson89]

OK, I'm lost here, so, please bear with me. I have a Mesa Mini Rectifier. It's got "gain" which, as I understand, controls the pre-amp signal (pre-amp volume) to the 12AX7s, right? And the "volume" controls the main amp EL84s, right? So how does that work if I dime the volume, then what? Is that out of the circuit? Is that a "master volume?"

For what it's worth I try to get the sound I like by driving the "volume" as high as possible to work the mains, and push the "gain" only as much as necessary to get the right amount of OD from the pre-amp with the least amount of "fuzz." I like a nice, round, creamy OD, and that seems to work best, rather than the opposite (high gain, low volume) which tends to be more saturated, less warm. It seems to work that way, to my ears anyway, and that's the way I've always approached amps with separate gain and volume controls. Am I on the right page and just don't know it or know why?

Yep this approach will get you power amp saturation, which is more the classic style of doing it (think ACDC, Rolling Stones etc). Amps with no master volume basically have a gain knob but no "volume" knob in that sense, so there's no attenuation (read master volume) into the power section, so you get this crunch happening from the power section when the amp gets loud. On a MV amp, when you turn the gain up and the volume down, you get more distorted sounds, they did this so you could get more distortion at lower levels, the difference however is you're only hearing the preamp valves distorting, this has its own sound, think more modern rock (Creed, Nickelback etc). I've always found that driving the power section will be a lot warmer and bigger sounding than driving the preamp section. So my preference is usually with old school crunch than high preamp gain, thats why low wattage amps are becoming popular, because you can get that power amp crunch at lower levels compared to bigger amps that were extremely loud at those levels (which is why they brought in MV in the first place).

 

[schwa]

I have a NMV Marshall (2061x), and a MV Marshall (2204). I prefer the NMV amp, but the 2204 can still sound pretty righteous - especially if the MV is above 5.

I'm no expert, and I don't know if the 2204 has a "bad" MV, but it definitely sounds better with the MV turned up.

 

[sepulchre]

I have a NMV Marshall (2061x), and a MV Marshall (2204). I prefer the NMV amp, but the 2204 can still sound pretty righteous - especially if the MV is above 5.

I'm no expert, and I don't know if the 2204 has a "bad" MV, but it definitely sounds better with the MV turned up.

There are two versions of the 2204. The earlier one does not have cascading preamp stages. Then Marshall realized that the cascading stages in the 2203 needed to be in the 2204 as well. I'm not sure of the date they made the change but it's easy to tell if yours has the cascaded preamp or not with this little test from The Vintage Marshall Guide:

"Just get two cables and plug them into both inputs of the amp. Turn it on and put your hand on the other end of the cables to produce sound. If you get sound only from one input, this means you have the cascaded circuit. If you get sound from both, you have a non-cascaded circuit."


Either amp should sound good with the Master turned up but the cascaded version will have some pretty decent drive at lower Master settings.

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