Gas Pedals DumbBell
Got a request for this one. It's an overdrive that's supposed to get you into Dumble sound territory. There are 2 versions of this pedal out there, a one knob version (with just a volume control), and a 3-knob version that the layout below follows.
Sewer Pipes Ring-Verb
Here's a cool PT2399-based circuit designed by David Edgar (DIYSB member Earthscum). He describes it as, "kind of like playing in a sewer tunnel..." Here's a link to the original schematic and discussion over on DIYSB. I noticed the schematic image in the DIYSB thread is now broken, so I've drawn up a new one for reference here.
Seymour Duncan Dirty Deed
Here's a pretty interesting distortion from Seymour Duncan. 2N3906 transistors for hard clipping and a two band gyrator EQ section. Originals I assume are all SMD and use MC33178 ICs, which I believe are equivalent to the LM833, but other dual opamps should work fine. Schematic here. Should be able to squeeze it in a 1590B with small profile jacks.
Run Off Groove Mockman 2.0
Continuing to knock out the last few ROG designs I haven't laid out. This one's a pretty easy little circuit, emulating the distortion in Rockman amps designed an used by Boston guitarist Tom Scholz. The toggle allows you to go between 80s (classic) and 90s (modern) tones, and it should all fit in a 1590a. Schematic, sound clips and more info on the ROG site.