Gain vs. Master

Hi there,

What is the different between “gain” and “master” in an amp?
I have the Fender Rumble 40.

I’m sure there are answers out there, but I like the way people in this forum explain things better than random answers I find on the web.



Gain is the input level (how “loud” the input is), master is the output level (how “loud” the output is).

Looking at where gain and master are on the Rumble 40 block diagram might also help understand their role:


Someone please correct me if I’m wrong, but the way I think I understand it… gain will change tone and could effect volume, whereas master volume will only change volume. So if you set the gain really high you should start getting some distortion, and setting it lower would be cleaner. The volume will then be able to make that tone as quiet or loud without changing the quality of the sound. So find the sound you want with gain, then set that to the volume you want.


Gain is how hot (loud) a signal is from your bass and effects going in to your amp. A lot of amps have some way to monitor if you are running too hot going in (distortion/clipping). A lot of people like to drive their amps hard ie close to clipping but I don’t. You can, like me, run in to problems of too much gain meaning that even with my volume turned down super low I still am too loud for my bedroom. Of course if I was onstage it would be a different story.