AM8110 Single VCA

Prototype AM8110

Overview This module is a clone of the VCA which appeared in two formats in the Roland 100M. A dual VCA with linear and exponential modes in the 130 module and a single VCA with linear mode in the 110 module. It is this former circuit I cloned in 2009 as part of my 100M replica project as a single VCA with both exponential and linear modes. This is a nice useful VCA with a clear sound and two CV control modes.

EuroRack Module:   14HP wide
User Manual:          Download PDF

Description The original VCA is based on the BA662 OTA chip, which I have replaced with the easier to find BA6110 which has 86dB Signal to Noise Ratio 0.5% THD. Whilst this is not a leading edge studio VCA, these specifications are fine for use within a modular synthesizer and are an improvement over the CA3080 used in many early 1970 VCA’s. I have modified the CV circuit to make use of easily available USA transistors (2N3904/06), and a TL071 Op Amp in the CV circuit. I have added a simple LED driver to display the post VCA audio level. The design was updated in 2017 to use a single PCB and vertical pots and jack sockets.

Module Availability The redesigned AM8110 will be available in 2018 as a completed module and PCB.

Copyright AMSynths 2017