The Volt Thrower is a modified RAT that was designed to work with bass. Everything after the first op amp stage was removed and a two band passive EQ, rotary clipping selector, and another op amp stage was added. An internal voltage inverter is also employed to increase headroom.
Two Band Passive EQ - Bass and Treble
Six Position Rotary Clip Control:
From Left to Right: LED Low Gain, LED High Gain, Silicon Low Gain, Silicon High Gain, Schottky, No Diodes.
There are also two internal trimmers which set the maximum gain for low frequencies, and the rest of the frequency band.
This unit internally creates twice the DC supply that is applied to the circuit. If a 9V source is used, it creates a -9V rail for a total of 18V of headroom. If an 18V source is used, it creates a -18V rail for 36V of headroom. Do not use a supply that is greater than 18V. Any center negative supply from 9 to 18V is acceptable.