HAO Rumble Mod

From the post

Request. It's probably worth considering using 2 independent 500K log pots and separating the boost and drive sides. It seems a little restrictive to have them as a dual pot rather than being able to set their gain individually and of course it may also be preferable to make the toggle a stomp so that you can change "channels" on the fly. A little wide to fit in a 1590B horizontally, but will fit in mounted vertically no problem.

Info about the original:

The ultimate overdrive unit, the HAO Rumble MOD RM-1 uses hand-selected components to provide the purest, smoothest, thickest overdrive ever. The problem with most OD’s lies in mismatched input/output impedances that can make components work overtime. The Rumble’s input and output buffers provide proper impedance matching, allowing its circuitry to focus purely on generating the fattest overdrive possible. The Rumble’s two modes of operation – Clean Boost in Mode #1 and Overdrive in Mode #2 – allow for a variety of applications and tonal options. If you’ve been searching for that $10K amp sound but are several $K short of the mark, the HAO Rumble MOD is the economical answer to your tone quest.