[sdiy] CA3280 VCA Design

[Ian Fritz]

At 10:20 AM 11/20/05, Rob Keeble wrote:
>Hi,
>I have a tube of CA3280's which I plan to turn into dual VCA's, however I
>can't find a circuit design on the web...so I have cobbled one together -
>which is here (37k GIF) - mainly using ideas from the SCI Prophet 5..
>
>www.emulatorarchive.com/assets/vca.gif
>
>Before I put this on the breadboard, any changes I should make?


Rob --

Your input network of 100k/330R is not appropriate.  Jim's design -- taken 
from the 3280 data sheet (Fig. 7) -- is the proper way to go.  To 
understand how this works and to modify it for your needs you need to study 
the data sheet.  (It isn't clear what your signal levels are.  Surely you 
didn't mean that the audio is 0 to 10 V?)  :-)

   Ian