[sdiy] very simple VCA circuit

[Harry Bissell]

LOL. I'd say the same for the LM13600/700, unless you use the diode bias circuit. If you do, the
VCA will clip horribly when overdriven, as opposed to the CA3080. ALL are noisy.

The CA3280 was the good stuff, now unavailable except at high prices from (often) dubious sources
(some folk have gotten counterfits...)

H^) harry


----- Original Message -----
From: Tom Wiltshire <tom at electricdruid.net>
To: Harry Bissell <harrybissell at wowway.com>
Cc: David G. Dixon <dixon at interchange.ubc.ca>, 'SDIY List' <synth-diy at dropmix.xs4all.nl>
Sent: Thu, 27 Jan 2011 08:44:44 -0500 (EST)
Subject: Re: [sdiy] very simple VCA circuit


On 27 Jan 2011, at 13:26, Harry Bissell wrote:

> why not the CA3080 of LM13600/700 ?  
> OTA have reasonably low component count, good to very good performance.

Sorry, but I can't accept this w.r.t. the CA3080. That chip doesn't do anything that I'd qualify as "good performance". If you're lucky, it'll stretch to "acceptable performance". Mostly it's noisy with obvious feedthrough.

Still, it probably compares pretty favourably to the one-transistor VCA that Justin suggested, though I've never tried that. And I do agree with Harry that the question is "how good does the VCA need to be?".

T.


-- 
Harry Bissell & Nora Abdullah 4eva