As mentioned over there, there are major differences between the stripboard here and the MS-20 filter version by Rene Schmitz, which I posted above. Partly because of the change from ±12 V power to +9 V but not entirely. The whole CV controlled current supply is removed, along with the CV input, there’s just a pot and a fixed resistor connecting +9 V to the LM13700 (which is standing in for the two CA3080s).
Specifically there’s a 100k pot and a 100k fixed resistor, so the maximum current is 9 V / (100k to 200k) = 45 to 90 µA, which is… wow, small. The LM13700 has a maximum control current of 2 mA (more will destroy it) and Schmitz uses 10k with a 15 V maximum voltage so that’s 1.5 mA maximum. But I guess for a guitar processor you want smaller output level so smaller control current. Maybe it makes sense.
On the signal input there’s a 100k/220k voltage divider, compared to 10k/220R in Schmitz’s. You want around 50–100 mVpp maximum on the input pin (see here) so Schmitz’ divider is really not so good for ~10 Vpp synth signals: 10(220/(10k+220)) ~ 220 mVpp is too big. But on this stripboard the 100k/220k divider is only cutting the input voltage by 50%! So the input should be not above 75–150 mVpp. That’s awfully small even by guitar level standards. Nope, I misread it, sorry.
Disclaimer: I don’t design or build guitar pedals. Maybe I’m just failing to understand a few things here.
Added: The schematic reconstructed from the stripboard is something like this, unless I’ve made errors:
The input divider is 100k/1k so maximum signal input is about 5 Vpp or higher, so no problem there.
In addition to the differences with the Schmitz circuit noted above, you can see the resonance circuitry has been reduced to an attenuator. In particular no clipping diodes to give the characteristic MS-20 resonance distortion. Altogether I’m doubting this circuit was based on Schmitz’s, and I’m not even too sure it was based on anything that could be called an MS-20 style filter. It’s more your basic vanilla LM13700 filter with single side supply.