To turn up a tube guitar amplifier's volume control to maximum. Doing so usually results in a distorted output that is aurally pleasing and rich in musical harmonics, compression and note sustain. Electric guitar tone enthusiasts often prefer this tone to other methods of generating a distorted output from the amplifier. However, the resulting high sound levels are often excessive and unusable in smaller rooms or environments where excessive volumes are not permissible.
Eric: Hey, Rich, last night at the gig I dimed my Marshall and got a sick tone, but it was so loud the club owner almost threw me out!
Rich: Sorry to hear that, Eric. That's why I play a teeny-tiny amp so I can dime it and not get hassled by my band, audience or venue manager!