[sdiy] VCA patent

[Paul Burns]

Don't get too excited about this VCA. The matching between the multiple
channels is good at max and min gain as it is fixed by the series and
parallel resistors around the FET, but at intermediate values is still
dependent on characteristics of the individual FET. 
So it is a good try, and not quite awful, but not something to base a
serious musical instrument upon, imho.
There are many VCA chips around these days offering better performance than
this has a chance of achieving.

Cheers

Paul

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of cheater cheater
Sent: 26 July 2010 19:45
To: Tom Wiltshire
Cc: synth-diy
Subject: Re: [sdiy] op amp based filter

BTW, here's a relevant patent that implements a voltage controlled op
amp. It's what I was referring to earlier:


http://www.freepatentsonline.com/5175508.html


Incidentally, it will expire in two years.

Cheers,
D.