[sdiy] Log/Lin VCAs/Transconductance amps

[Tom Wiltshire]

There are a number of VCA chips still in current production and  
available:

SSM2164 quad vca
SSM2018 single VCA
THAT2180/2181 single VCA
THAT2162 dual VCA

All of these seem to be designed primarily for audio level control,  
and have a dB/mV control response (log). This contrasts with what I  
think of as the "previous generation" of chips for VCAs:

CA3280
LM13700/13600
CA3080

All of these basic transconductance amps have a linear response.  
Obviously there were a few SSM/CEM VCA chips around too (CEM 3360  
dual VCA for example) but these are in general even more expensive  
and harder to get than the short list above.

Does anyone know of a cheap/easily available linear VCA or  
transconductance amp?

Perhaps I'll have to linearize the SSM2164 and use it as a dual  
linear VCA instead. This provides an upper limit on cost, since the  
SSM2164 is about £4-5.

Thanks,
Tom