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A pair of 2sk117-GRs gives less gain, but a similar tone roll off (according to ltspice). I'll see if I manage to breadboard it this weekend

LTspice comes with some stock models for 2N4393 and PN4393, are you using those? I'll try to play a little with some other jfet models and try to match it a little

Looking for some higher gain pedals, so I'm definitely interested in this one! What makes the 4393 so critical? A particular combination of Idss, Vgs and capacitance?

Beautiful!! Love the graphics

I love this! DIY in all its glory

Good news that you got it to work! Hint: you're looking for a non-inverting operational amplifier stage

I'm no master by any means, but I find it very interesting. A bit of a learning curve, but nothing terrible.

have you tried it with a buffer? a boss pedal, for example? IMO 'properly' is a trick word to use here, because I'd say it works properly when it sounds like it should, but I see what you mean. I'm not sure that's what's going on, but it might be a case similar to those fuzzes (like a fuzz...

As I've mentioned before, I have very little understanding of the concept of impedance so take everything with a grain of salt. Running some tests on LTspice, I've noticed that, when you plug a guitar straight to the input (assuming my pickup simulation is correct) there's a lot of treble roll...

I find it very useful to evaluate impedance with LTspice. Simulation of the input stage of the mosfet drive results in the following:

Impedance is too big of a word for my small brain, but I do find the value of R3 (10k) kind of small when compared to other buffers. Too small of an input impedance might be responsible for this chain-placement-dependent behavior

The Wampler Black 65 is supposed to give you some of that Bassman flavor. Not sure where/if somebody sells a PCB, though

Beautiful job, as always! Compared to other distortions/drives, how much gain would you say this one has? The 3 mu-amps have me a bit scared

About the fet, I think you can replace the j201 with a J113, since it's acting as a source follower Your math is correct, but not entirely: the cutoff frequency of a 1k-6n8 lpf is indeed ~23khz. However, a 1st order lpf begins attenuating before said frequency. If I'm not mistaken, the cutoff...

You're right, pinout is the same, but I think they have a different footprint, like those two: The sk118 looks like the one on the right, and I think (never had one in my hands, though) that the sk30 looks like the one on the left

That's true! I had forgotten about the 2sk30! It's just a different package, if I'm not mistaken

The 2sk208 is the smd equivalent of the 2sk118 and it's still in production. Both mouser and digikey carry the 2sk208-Y (as does aliexpress, not sure if it's worth it, though). You could buy it and use an adapter board

I've been there, I know your pain

Nice job! Clean as always! Have you had to twist the knobs on the transistors? I thought the pinout on the J113s was differente from the pinout on the 2sk170s, but it doesn't look like you did

In terms of Vgs(off) the 2sk209 (available in smd still in production) is an exact match to the 2sk170 (they both range from -0.2 to -1.5). It would be important to know the suffix on the 2sk170 in order to get a similar Idss. The pf5102 might not be a bad match either (but the pinout is...