master, volume and gain

[ted s]

Hey folks, maybe a dorky question here..
What is going on with the manipulation of these adjustments on an amp (aside from getting louder)
Semi-technical answer ?
I have a Vox ad30 and have not messed with the adjustments much, just spin the dials until I find something I like. That got me thinking, what the he77 do I do with all these other adjustments on this magical box ?
I would have thought that master would have acted like a limiter of some sort, but that is the job of attenuator on the back. That's when I realized I didn't have a clue.

Thanks for any enlightenment.

ts

 

[TS808]

At low to moderate volumes, with the master up and the gain down, you'll get a cleaner sound. With the gain cranked or set high, and the master lower, you can expect more preamp distortion. With the gain and master cranked..tonal heaven...the preamp and power amp will distort, but you may go deaf : )

 

[duhvoodooman]

OK, not sure if I remember this all correctly now, but I think this is right:

The Volume and the Master Volume do pretty much the same thing, but the Volume is programmable where the Master is not. That is, when you save the amp settings into memory, the Volume knob setting is stored, but the Master is not. Other than that, they seem to be completely redundant. At least I've never been able to hear any difference between turning one up as opposed to the other. As far as the signal chain goes, they're both between the preamp and the power amp stages.

The gain knob works two different ways. For the amp models where the original had a gain knob, it functions as such, loading up the preamp stage more or less. This is what tends to most noticeably affect the distortion level on these models. For models where the original amp had no gain control, the knob becomes a third volume control, and functions exactly like the Volume knob does. It, too, is programmable.

The Power Level knob on the back determines the maximum output of the final power stage, apparently after the 12AX7 "valve reactor", since turning it up or down seems to affect nothing other than the amp's final volume. Maybe with everything dimed, you could get enough power through the speaker to get a bit of break-up there, but I doubt it. As I recall, it's rated to take considerably more power than the amp will put out.

Like the Gain knob, the AD30VT's tone stack also operates variably, depending on the amp model selected. On some models, the T-M-B controls are completely independent, but on others they interact quite strongly. So don't expect the same set of three settings to work the same way on each model--they don't. You just have to fiddle around to get the tone to taste.

Hope that helps....

 

[ted s]

thanks guys