Dual SVF: second filter almost inaudible


I was trying to tune the Dual SVF board, when I discovered that the second filter was inaudible. You only hear a very faint hiss when the cut-off is at 127 with full resonance.
And indeed when editing a sound if you put the 2 filters in serial, there is no sound coming out (just the same finte hiss when you push the cut off at 127).
Anybody have a hint on what to check?
I checked the voltage for the 2 V2164 and I got +4.91 and -4.95v for both ICs (at the points indicated on the 4-pole mission’s page since there’s no indication on the Dual SVF page).
Thanks in advance.


at full cutoff and full resonance i think it’s normal to only get that hissing. it’s better to tune them with cutoff at half (or something, i think the exact value is mentioned in the build docs)

I know, but with cut-off at 64 and resonance at 63, there is no sound at all coming from the second filter.

After several tests, I inspected closely the 4053N and TL074P solder joints and found a bad one there. Cleaned it, re-did it and here is the 2nd filter back!