[sdiy] Best VCA circuit for synth module..

Tom Wiltshire tom at electricdruid.net
Fri Oct 5 11:04:35 CEST 2012


On 4 Oct 2012, at 20:05, David G Dixon wrote:

>> What would be the best VCA core design already available on the net ?
> 
> Phil Gallo's take on Mike Irwin's linearized 2164 VCA concept.  This (with a
> few changes and improvements) is the basis of my standard VCA design, the
> Intellijel uVCA, as well as about a dozen others on the market.
> 
> There are a few things one should do to make this VCA work really well.
> Email me privately if you're interested in the details.

I agree - for linear VCAs, the linearized SSM2164 is tops. Anything else is based on an OTA and the signal level has to go right down to mVs and then back up again - hardly ideal.
For Log/Expo (whatever you call it, and don't let's debate that *again*) you've got more choices. The SSM2018 is a very nice clean VCA, and the THAT chips are excellent too.
Tom Farrand's RFE-117 VCA is a nice example of a top-end SSM2018 VCA:

http://www.radio-flier.com/PDF%20Files/RFE117Sch.pdf


HTH,
Tom


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