MOTM

1) It's easier to design a linear VCA. *Much* easier!
2) For volume level-type apps, you want an exponential response. But if the
CV is expo.
(ie an ADSR) then the VCA can be linear. (log x linear = log)
3) Log on a VCA is good for percussion (log x log = quadratic response). You
get
"Super Attack Transients" this way. Also, if you CV source in linear (say, a
foot pedal)
then for volume apps you reverse the symmetry (audio goes into Log in, CV
goes to linear in).

Paul S.

-----Original Message-----
From: Tkacs, Ken <Ken.Tkacs@...>
To: 'motm@onelist.com' <motm@onelist.com>
Date: Friday, October 29, 1999 2:32 PM
Subject: RE: [motm] More VCA blabbering


>From: "Tkacs, Ken" <Ken.Tkacs@...>
>
>
>The ear response to sound pressure levels (amplitude) in a log (anti-log?)
>fashion is way similar to the way pitch works.
>
>You know how, in a VCO, you have the choice of designing it to either
>respond exponentially to linear CVs (the Moog/MOTM way) or to respond
>linearly to exponential CVs (the Korg MS-series way).
>
>Same goes for a VCA. It's usually cheaper and more direct to design an
>amplifier that responds linearly to an exponential control contour,
>especially since ADSR envelopes are usually created from charging
capacitors
>which tend to exhibit the exp. curve anyway. But it doesn't have to be that
>way.
>
>However, let's say you want to use the VCA to control something other than
>an audio signal. What if you want to use a CV to control the gain of
another
>CV, in other words, use the VCA as a voltage-controlled resistor? Then you
>most likely will want to use a linear CV in and a linear response to it.
>
>If I'm wrong, somebody hit me with a wet noodle. It's late on a Friday and
>I'm not thinking properly. Something in what I just wrote doesn't ring
right
>but I'm too brain dead to troubleshoot it.
>
>I know what it is. It's ANTI-log, right? So you need the exp. response to a
>linear CV if you aren't using a CV input from an AL source such as an EG.
>
>I give up, what's the answer?
>
>
>
> -----Original Message-----
> From: J. Larry Hendry [mailto:jlarryh@...]
>
> What would I use a linear input on a VCA for unless I was
>using EGs with
> linear CV outs?
>
>
>>