GuitarPCB has their "Mini-Me" (modified EHX Small Clone clone) that fits handily into a 1590B. I even add a mod to the ones I build and still works well in a 1590B.
I've pre-ordered a few of them from CabinTech Global to try out. After reviewing the datasheet and comparing to other 8-pin DIP BBDs, they are not pin-for-pin compatible. So a new layout would be needed. Considering the SSI2100's power requirements, I do see that it might be possible to create...
Have you been reading any material on the FV-1 or SpinCAD? I recommend this link for a more focused look at the Pitch Shift block.
And the only reference I have for pitch control is this chart . . .
Considering the FV-1 has a pitch limit of 1.2 octaves down and a max of 2.0 octave up, I use...
By the description of the problem(s), it sounds like an intermittent connection. I'd reflow EVERYTHING and give it another go.
If it still goes wonky, put it on the bench and test the voltages for the +9V and +3.3V supplies and lines.
Yes. Use the 33pF (C4) cap.
No. Using the 33pF cap does NOT have a negative impact on the sound. It's part of the circuit design and used in most every Rat build.
If I'm not mistaken, the +18V and +15V are the unloaded PS values. With the loads applied, the voltages work within the design parameters of the circuits' design and components. I'd stick with the BOM and designated component values to avoid any issues.