YuSynth EMS VCF ready!

My first VCF is ready! The YuSynth EMS VCS3 diode ladder VCF clone is a cool sounding filter, and it has special resonance behavior. Based on the YuSynth section of the E-M forum, the value of the resistor R41 may need to reduced, to match the 2N3819 JFET characteristics. I can't able to reach self-oscillation with the standard 680K, so I reduced it to 220K and then

to 180K, which is finally correct.

The TL074 which I've used was faulty, so the control and the input levels are started to wiggle after a few minutes, and large amounts of noise went to the output. After some "air cooling", the levels are normalized, and the noise was dissapeared, at this point I've realized, that this opamp need to be replaced.