3xVCA
User Manual v1.1
Overview
3xVCA is a trio of VCAs. They have a
linear
response to CV input, and are equally suited to
controlling the amplitude of audio or CV signals.
The VCAs are made using no special ICs. Rather each is made with matched transistors and
0.1% components.
Technical Specifications
● Width 6hp
● Depth 28mm
● Current draw 20mA @ +12V
● Current draw 30mA @ -12V
Inputs
IN
+/-10V range. DC coupled. 100K impedance. These are the main inputs for the signal to be
manipulated.
The IN jacks are normalled together from the top down. For instance, a signal patched to the top
IN will be present at all three OUTs. Patching into a lower IN will break this normalled
connection.
CV
+/-10 range. DC coupled. 100K impedance. The voltage applied here controls the gain of the
VCA. A positive signal increases gain, and a negative signal decreases gain. A +5V signal
opens the VCA to unity. A max gain of 1.6 is possible if CV is applied “on top” of a fully
clockwise LEVEL control.
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