[sdiy] Lin/Log VCAs and envelopes - compensating for log VCAs

[mskala at ansuz.sooke.bc.ca]

On Sat, 6 Feb 2016, Tom Wiltshire wrote:
> I've been thinking about linear and logarithmic VCAs and ADSR envelopes.
> We're usually told that the standard exponential
> cap-charging/discharging ADSR curve into a linear VCA produces a
> "natural" sound, because our ears understand volume logarithmically -

Who says that?

People call the cap-charging curve "exponential," but as your charts show,
it's the wrong kind of exponential - moving fast at the start of each
phase and slow at the end.  The exponential response of our ears should
demand, for linearly increasing perceived volume, slow movement at low
voltages, regardless of which direction it's going, and fast at the high
voltages.

I'd really like to have an ADSR with linear voltage/time curves, and then
feed that into an exponential VCA.  That would give linear perceived
volume (assuming the exponential-perception hypothesis is right, which I
think it basically is).

-- 
Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before principles.
http://ansuz.sooke.bc.ca/