Synthmonger CMOS Resonators demo quicky

The design is based off Korg's PS3300 Resonators. I use just resistors, diodes, capacitors and CMOS chips. No vactrols, op amps or transistors.

Audio signal is my casio VL-1
The frequency of each filter is being modulated by a slow triangle LFO
I adjust the master VC resonance control three times.
PCB for the project will be available at my etsy store, as well as completed modules.

Category:

Music

Tags:

• Korg
• Resonators
• CMOS
• Lunetta
• analog
• modular
• synthesizer
• VCF

[synthmonger]

check the EM forum for my CMOS VCF post. Can't post links here for some reason...

[synthmonger]

I replaced them with 4066 that were clocked with a high frequency VCO which turned the e-switches into voltage controlled floating variable resistors. At certain frequencies you could hear the bleedthrough from the vco; the signal sounded too dirty. I saw Rene's schematic for a 4007 based vcf and vca and tried using NMOS in place of the vactrols but I had no such luck with them. I swapped the NMOS for PMOS and everything worked perfectly. I had to scale the CV with a spare inverter.

[synthmonger]

Yea the original resonators used three prong vactrols that were pre-fabed by Korg I believe. Now a good ol' VTL5C4 works great.

[EA78751]

I'm lookin at the PS3300 resonator schemos. Are the things labeled F101-F103 some kind of vactrol?

Did you have to try a lot of stuff to replace them?

[synthmonger]

thanks!

[EA78751]

sounds awesome!