[sdiy] SSM2164 to use as ring modulator...

[Tom Wiltshire]

It sounds like it would work, but keeping the switching noise out of the output is likely to be difficult, imho.

Better to adopt the "balanced" approach Neil mentioned. The concept of it can be understood like this: Feed some of the inverted signal through normally, and then bias the VCA so that it feeds enough non-inverted signal through to cancel it. Reducing the VCA CV reduces the cancelling signal and gives you more of the inverted copy, increasing the VCA CV gives you more non-inverted signal. Hey Presto! Ring modulation!

Neil's right about this having been around for a long while too. That magazine article features the same CA3080 ring mod circuit I built from one of Ray Marston's books at least 25 years ago.

T.

On 14 Feb 2014, at 11:28, Rutger Vlek <rutgervlek at gmail.com> wrote:

> Hi all,
> 
> Interesting topic! It's only remotely related, but I've always been wondering whether a ringmodulator (balanced modulator) could be constructed from a simple VCA and an analog switch that flips the polarity of the signal. So, let's say you have a modulator signal between -5 and +5 volts. When the signal goes from 0V to +5V it opens the VCA in a normal manner. When it goes from 0V to -5V the modulator signal is inverted (turning it into 0V to +5V) so that it opens up the VCA in exactly the same way as it would, but the VCA output is inverted too. Has anyone ever tried this? I believe with sufficiently fast switching and a reliable comparator, it should work.... You could even make the switching and comparator circuits part of a companion module that combines with a VCA of your choice...
> 
> Best,
> 
> Rutger
> 
> 
> 
> 
> On 13 feb 2014, at 21:27, Jean-Pierre Desrochers wrote:
> 
>> Would it be a good idea to use the venerable SSM2164
>> for a ring modulator project (dual, quad)?
>> The modulation could be log (by default) or lin
>> with some tweakings..
>> I could also use the AD633 but I'm just wondering.
>> I already have plenty of 2164 chips so..
>> 
>> JP
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