The Synthrotek Triple Response Dual VCA uses high quality op amps to give you the sound quality you are looking for in affordable kits and completed units.  This VCA has three different response curves per channel: 2 Exponential and 1 Linear.  The amplitude of EX2 (switch at right position) can be slightly attenuated via 1 trimmer pot per channel on the PCB.  This allows for 3 different curves per channel.  EX2 has a slightly more exponential curve than EX1.  This VCA operates at 0-5V; a 5V CV input will give you 5V point to point audio output.  Use over 5V if you want a super ballsy, loud VCA!

Intended for AC and audio use only (DC coupling will not function properly).

Features include:

– ~5V peak to peak output with a +5 DC CV input

– 2 exponential and 1 linear response per channel

– Channel 2 is normalled to channel 1

– Compact 4HP sized module

– Kits, complete and PCB/panel combos

– High Quality Op Amps

– Module depth: 1 7/8 inches (4.7 cm)

– Max current draw: 1mA on -12V rail, 9mA on +12V rail
Purple: Linear Response.
Yellow: EX1
LINEAR and EX1 mode
Purple: Linear Response
Yellow: EX2
LINEAR and EX2 mode


  1. Christian Meyer says:


    Would it be ok to use 1% resistors in this build?



  2. Steve Harmon says:

    Hey Christian,

    You can definitely do that! 1% are going to be closer to the advertised values anyway. You wouldn’t want to use 5% in place of 1% without actually measuring each resistor.


  3. jenz says:

    Just to say that we ne year ago I have built that VCA and only one channel was working and the response switch wasn’t.( I was soldering like a miserable door knob). Today, I have reflowed almost all of the solder joints and now it’s working properly. So happy to have this VCA

Leave a Reply

Your email address will not be published. Required fields are marked *