ideally: in a tube amp.

in-> tubestage(1a) -> gain -> tubestage(1b) -> tubestage(2a) -> Tone stack -> tubestage(2b) -> MasterVol -> PI(3a+3b) -> Powertubes

1a will amplify your signal to a level to push the next (1b) and overdrive very slightly, which will then amplify the signal again and push (2a) to some saturation. tube (2b) is to counteract the loss that occurs in a tone stack, so you vey rarely drive this to any distortion BUT sometimes are wired to overcompensate so when MasterVol is turned up, 2b does drive hard enough (with all the other tubes help) to push the PI into a bit more compression etc.

looking at my above paragraph, add a Boost (not distortion) pedal in front. you literally have a 2nd gain control as now 1a also gets overdiven, so 2a will in turn be hit by a way way hotter signal.

Gain is a volume control somewhere in your preamp that helps control the cascading effect of overdiving tubes. ?
MasterVol is the Volume of the preamp hitting the poweramp.

The Marshall JCM 900 manual states:
To get maximum valve performance, set the master volume as high as possible and control your volume with the pr-amp gains.
Does this make sense ?

Gain is voltage increase whereas volume is what comes out of your speakers. They are the same unless there are stages in your amp being driven into compression.

Gearhead wrote: Gain is voltage increase whereas volume is what comes out of your speakers.

+1. I was taught never to use the word "volume" unless I was talking about dB SPL - and even then, rather to use dB SPL. But in a guitar amp, there are different naming conventions that guitarists understand, although they are not, strictly speaking, correct. Like "Vibrato" (which is actually tremolo).

So "Gain" is usually the amount of overdrive from the preamp valves, while "Volume" is how loud it is. Note that at lower gain settings, the gain will also affect the volume and at higher volumes an amp's power amp will distort too, so there is a lot of interraction.

Vintage and many vintage-style amps just have a volume (which is actually gain) and you have to turn up to get the amp to drive. More modern amps may have gain and volume per channel and then even a "master volume" controlling the overall volume too.

In the previous post, the Volume I was referring to was Pre-amp volume ?

So is an amp with a Gain -> M Volume the same as a Pre-amp Volume -> M Volume?

If Gain is the amount of overdrive of the valves and Pre amp Volume drives the valves, is it not the same?

Mattocaster wrote: So is an amp with a Gain -> M Volume the same as a Pre-amp Volume -> M Volume?

Usually, yes.