[sdiy] VCA distortion - bad

[Tom May]

The problem I have with this circuit on my ASM-1 is a small burst of
noise in the output as the control voltage decays past the point of
silence.  It's not a very loud noise, but I can hear it in headphones.

Tom.

harrybissell <harrybissell at prodigy.net> writes:

> This is with the topology where the negative rail of the OTA is varied with
> the CV. I saw this in a Craig Anderton design (and also in Electronotes as you
> mentioned)... but I have never tried it.
> 
> It certainly saves having to use a PNP current source to drive the Iabc pin
> (referenced to the negative rail) but I always wondered if it would affect the
> headroom.
> 
> So anyone tried this and vouch for it ???
> 
> H^) harry
> 
> Michael Ruberto wrote:
> 
> > I was wondering if it's possible that the op-amps I am using might have too
> > hot an output. in the original schematic Bernie specifies a LF353 and I am
> > using a TL072. could there be enough of a difference in the current sinking
> > ability between these devices to cause the overdrive?
> >
> > ~M
> >
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