This is a single-channel VCA based on a THAT2180 chip. It’s ultra clean and sounds fantastic. It’s a perfect sonic companion to the MA MIX and also works well as a final output module.
The VCA has a manual gain control (offset) and two independent CV inputs, both with an exponential (audio) response curve. They are configured to take 0-5V CV signals which will open the VCA fully to unity gain. CV inputs above +5V are diode-limited, a feature which can be exploited to change the effective curve of an envelope signal (similar to a “hold” stage in an AHDSR envelope). The inputs of this VCA is AC-coupled, so consider this one for audio only.
VCA – Build Document & BOM
Note: This PCB has the 3 x SMD 0.1uF ceramic capacitors already pre-soldered, TL071 is a suitable replacement for the now hard to find LME49710 chip.
- Width: 4HP
- Depth: 39mm
- +12V: 10mA
- -12V: 15 mA
- +5V: 0 mA