RS serge variable q vcf troubleshooting

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, Joe.

Post Reply
transistorresistor
Wiggling with Experience
Posts: 307
Joined: Mon Apr 27, 2020 9:38 pm

RS serge variable q vcf troubleshooting

Post by transistorresistor » Sat Apr 03, 2021 6:54 pm

Im not familiar enough w this circuit to have a good sense of how its supposed to work, but I recently built an RS VQVCF and it wont self oscillate at all. In band pass I can get it to self oscillate for about 3 seconds w a decay to silence. I used THAT chips, seems like this filter normally should self oscillate but not quite sure where to start trouble shooting it. Sounds great but it does also have a very odd resonant peak. Just curious if anyone has encountered this type of behavior w the RS layout.

User avatar
diophantine
Super Deluxe Wiggler
Posts: 2379
Joined: Mon Jan 10, 2011 2:50 pm
Location: San Diego, CA, USA

Re: RS serge variable q vcf troubleshooting

Post by diophantine » Sat Apr 03, 2021 6:59 pm

Is this the Eurorack or 4U one? Through-hole or pre-soldered SMT?

Do you have bandpass patched into the input? Resonance and gain turned up?

transistorresistor
Wiggling with Experience
Posts: 307
Joined: Mon Apr 27, 2020 9:38 pm

Re: RS serge variable q vcf troubleshooting

Post by transistorresistor » Sat Apr 03, 2021 7:03 pm

sorry, euro rack through hole. Feel totally foolish, didnt have it patched to the input, problem solved lol.

I just had the BP patched out and wasnt seeing a sine wave, patching the input rectifies that. cheers.

User avatar
diophantine
Super Deluxe Wiggler
Posts: 2379
Joined: Mon Jan 10, 2011 2:50 pm
Location: San Diego, CA, USA

Re: RS serge variable q vcf troubleshooting

Post by diophantine » Sat Apr 03, 2021 8:29 pm

Awesome, glad it is sorted out now!

Post Reply

Return to “Music Tech DIY”