MFOS SVF (On the SL MK2) not working

[Jack Gull]

Hello electro-music,
I am having problems while building my Sound Lab MK2.. The filter is not working.
First, i have used all the correct components (types, values, tolerances)... well except for the integrating caps that are 220p (i only had them laying around) but it shouldn't affect the functioning, right?
I tried building the filter four times actually:
- On breadboard (didn't work. i always had the output of the first OTA stuck at -12V iirc.)
- On a self made 12dB SVF board (didn't work, same thing)
- On a SECOND self made 12 dB SVF board (didn't work, same thing)
- On a MFOS SL MK2 PCB
Now, it doesn't work, as a filter, but i'm getting a small input bleedthrough.. which i might consider an improvement?

Anyway, for the input i've used the oscillator or the noise generator of the board, so the levels should be matched.
i verified that the exponential converter is working correctly (feeding it with a ramp or a triangle gets an exponential ramp/triangle at the output) so i suspect that the culprit is in the 13700 area?

I already tried swapping it with new 13700s, but the result have always been the same. They might have been all bad ones (i didn't bother testing the new chips) so i'll go get some others, but.. is there something else i could have missed?

Thanks guys

[Jack Gull]

Hope i can bump my thread.. can hear the filter sweeping but output volume is daaaamn low.
this is really frustrating for me As i said, VCA VCO and Noise work and sound really great. but still not the VCF.. i changed everything again. Still doesn't work, but there is some kind of improvement. Now that i threw away the caps and put new ones and changed the 13700 with a new one i hear a filter sweep. The downside is that the output volume is very, very low. Lower than the background noise of the VCA. i've recorded a short clip of what happens https://soundcloud.com/jackmonegato/filternoise
do you have any suggestion?