The opamps in the original are three dual-opamp NJM4558, which is a bog-standard dual-741 bipolar type. So pretty much any bipolar opamp should work just fine, I would think. I have 4558s - they're dirt cheap - so I used those, but I used sockets so I might try swapping them for something else and see if the sound changes at all. I might try #JFET ones like #TL07x .

The silicon clipping diodes in the original - in positions D3, D4, D5, D8, and D9 - are 1S2473 . I used #1N4148 instead.

There are also a pair of germanium diodes used for inline clipping (as opposed to more common signal-to-ground clipping). These are in positions D6 and D7. The original uses 1S188FM, and I substituted #1N60 .

The original circuit uses 5 different types of transistor, but one of those is only used in the soft-switching bypass route. So the only ones needed with my modified schematic are Q1, Q3, Q6, and Q7:

Q1 - original #2SK30A-Y N-channel JFET type. Unlike the rest, this one is still widely available, and I had some.

Q3 - original #2SC732TM-GR silicon NPN. I substituted #C945 / 2SC945.

Q6 - original #2SC2240-GR silicon NPN. I used #BC548 / SBC548.

Q7 - original #2SA970-GR silicon PNP. I used #BC558 / SBC558.

I used sockets for all the diodes and transistors, so I might try swapping some of those around too.

I might take some photos of the finished boards and add them tomorrow.

Hope someone found this interesting!

5/5