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.
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 2 years ago
check the EM forum for my CMOS VCF post. Can't post links here for some reason...
synthmonger 2 years ago
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?
EA78751 2 years ago
Yea the original resonators used three prong vactrols that were pre-fabed by Korg I believe. Now a good ol' VTL5C4 works great.
synthmonger 2 years ago
sounds awesome!
EA78751 2 years ago
thanks!
synthmonger 2 years ago