VCA3080

Included in the MRB Luxury Filter Bundle

The VCA3080 is the companion module to MRB's Syrup. Syrup is missing the VCA found in MI's Ripples. Rather than include it within Syrup, we decided to break it out as a separate module to provide the maximum in patching versatility. Both mono and poly versions are included free in the Syrup Bundle. Ripples' VCA is an LM13600 chip which is based on the CA3080. What's a CA3080? I thought you'd never ask.

The CA3080 transconductance amplifier chip, invented and produced by RCA in 1969, was at the heart of countless analog synthesizers of the 70s, 80s and beyond. It distorted and was noisy, but it was cheap and convenient. Therefore, this 8-pin wonder found its way into Moog, ARP, Buchla, Roland, Korg, Emu, and many more synthesizers enabling voltage control of parameters that used to require you to turn a dial to vary. Things like the gain of an amplifier, cutoff of a filter, and pitch of an oscillator were all made voltage controllable with the CA3080. You might say it put the "VC" in "VCA", "VCF", and "VCO". It can also perform more functions too numerous to list here. If you asked 100 synth engineers and technicians what the most important chip used in analog synthesizers was, they would all answer the CA3080. Alas, the CA3080 is no longer manufactured, but it has been replaced by a dual version called the LM13600 which is itself endangered. However, huge demand from the analog synth community has caused a couple of small companies to produce them again in limited quantities.

The VCA3080 by MRB is a faithful recreation of a typical VCA from the 1970s. The distortion characteristics have been faithfully modeled, but not the noise. (If you want noise, you can always add it with a noise source module). All the great features have been borrowed from the MRB Laboratory VCA, but where the Lab VCA is squeaky clean, the VCA3080 can be made to grind.

Inputs and controls are all pretty much the same as on the MRB Laboratory VCA, so a read of that description will cover everything. The one addition is the DRIVE knob, that when cranked, pushes that differential transistor input stage model into heavy distortion. The distortion is primarily odd harmonics, but if you add a little DC to the signal, you'll get even harmonics too. As a matter of fact, the CA3080 chip could only tolerate 20mV of input level before distorting (so the signal had to be padded down going in and re-amplified coming out), characteristics which were sometimes annoying and sometimes wonderful. But annoying or wonderful, it definitely had a sound.

Patching the VCA3080 after Syrup gives another dimension to the sound possiblities. Try plugging the various Syrup outputs into the + and - inputs, crank or lower the DRIVE. You'll be amazed at the variety of timbres.