What do the knobs on a guitar amp do?
It's obvious from the labels what most controls on guitar amps do: the Treble knob adjusts treble (high) frequencies, the Bass knob adjusts bass (low) frequencies, and so on. ... This means they do their tone shaping before the signal reaches the power amp and is amplified to drive the speaker(s).
What is the Drive button on an amp?
On some amps, you can control the level or strength of the signal sent through this first stage; this control is called "gain" (also often labeled as "drive").