[sdiy] Good Expo curve for VCA use..

[Jean-Pierre Desrochers]

Good point Tom,

I was thinking of having both Exp/Lin choices on my VCA's
and maybe a way of mixing them (or not) with a pot maybe
could be interesting.. but not sure yet.
And I'm also facing the decision of making the module
using 1U or 2U width... Depends if I put pots on some CV
and audio inputs. Probably.

JP

Le 2012-10-15 15:00, Tom Wiltshire a écrit :
> Hi JP,
>
> I agree with Mattias; a typical "expo" VCA uses curve Expo2. This
> includes the SSM2164 or anything by THAT Corp.
>
> However, the typical synth VCA fed by a expo ADSR is a *linear* VCA
> (thinking Minimoog, Pro-One, etc). The expo effect is caused by the
> cap charge/discharge curves on the envelope, rather than by the VCA
> directly. It seems to me that including an expo input on synth VCA
> chips got a lot more common (though by no means ubiquitous) with the
> later CEM stuff that was intended to be used with 1980's
> microprocessors and therefore with linear envelopes (CEM3378/9 for
> example).
>
> HTH,
> Tom
>
>
> On 15 Oct 2012, at 17:02, Mattias Rickardsson wrote:
>
>> Expo2 if you want to fade in/out slowly and evenly...
>> in a dB sense, for your hearing. :-)
>>
>> /mr
>>
>> On 15 October 2012 17:20, Jean-Pierre Desrochers 
>> <jpdesroc at oricom.ca> wrote:
>>> Hi List,
>>> Suppose one have a VCA with only linear control voltage
>>> inputs but want to feed it with an Expo control voltage..
>>> What would be the good expo curve to use ?
>>> See this picture for answer:
>>> http://www.arcenson.com/public/VCA%20curves.JPG
>>>
>>> Expo1 or Expo2 ?
>>> A standard ADSR would generate Expo1 to this VCA
>>> but I want to make sure..
>>> Thanks
>>> JP
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