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ED104 - Dual Lin/Log VCA
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The ED104 comprises 2 LIN/LOG VCAs with additional VC Panning function.

In July 2002, EDN Network published an article by Mike Irwin on the application of op-amps to linearise the response of a voltage controlled attenuator built around the Analog Devices SSM2164.

In September 2003 Phillip Gallo published a design for a Dual LIN/LOG VCA utilizing this design idea and the ED104 realises that design in a euro-synth module.

Although the ED104 has two separate VCA’s, the [LIN/LOG] control law is switched simultaneously for both VCAs so that they both operate with the same control response.

In stand-alone mode a control voltage is fed in to [CV x] while an audio signal is fed in to [AUDIO IN x] with the resultant output at [AUDIO OUT x].

With the CV level control at maximum, a 0V to 5V signal will raise the gain of the VCA from -100dB of attenuation to 0dB while increasing the voltage from 5V to 10V will further increase the gain from 0dB to +20dB.

For operation in Panner mode, a single audio signal is fed in to [PAN AUDIO] while the panning control voltage is fed in to [PAN CV]. The [CV A] and [CV B] level pots should initially be set to maximum


Module Width
Module Depth
+12V @
-12V @

Build Guide

Email:  elby-designs@bigpond.com
© Copyright 2000. All rights reserved.     Revised: February 27, 2020