[sdiy] Simpliest envelope follower

[elmacaco]

I copied an Env Follower from one of Tom G's EFM modules when I wanted a
simple one.  Very low part count, very easy to build.  I think it is part of
one of his filter designs, it is clearly labeled on the schematic and I
think it was just a dual op amp and some other little bits.


----- Original Message -----
From: "harrybissell" <harrybissell at prodigy.net>
To: "Johannes Öberg" <johannes.oberg at gmail.com>
Cc: <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, April 20, 2005 9:56 PM
Subject: Re: [sdiy] Simpliest envelope follower


> Yes... you could do that. You probably need an active full-wave
> rectifier (opamps) not just a diode bridge here.
>
> WHAT are you going to follow ? This is VERY important.  For instance,
Rene's
> circuit samples the peak then resets at the zero cross. A good technique
if the
>
> waveform has one zero cross per fundamental cycle.  Guitar, for example...
does
>
> NOT.   My design idea in EDN "envelope follower combines fast response,
lowest
> ripple works especially good for Guitar, beating the simple full-wave and
peak
> detect methods hands down.
>
> iirc... I think Rene's circuit is much less complex than mine.  ;^P
>
> otoh if you are going to follow DRUMS, a peak detector is the way to go.
>
> The morphlag is a good filter circuit for either a peak detector or a
fullwave
> rectifier.
>
> H^) harry
>
> Johannes Öberg wrote:
>
> > Hi! I'm finally going to put together a Rene Schmidt MS-20 filter, but
> > I really want some envelope follower modulation on the cutoff. What's
> > the simpliest / lowest part count design that produces acceptable
> > results? The one on René's page looks simple enough, but I want lower
> > parts count :-)
> >
> > I'm to stupid to isolate the envelope follower in the DrQuack
schematics...
> >
> > What if I try a fullwave rectifier with Harry Bisells Morph-Lag? Or am
> > I completely on the wrong track?
> >
> > If it matters, the filter would be used for uhr, "general purpose
> > filtering", whatever that is. I guess I would be using it more on drum
> > parts or 'the mix' rather than single instruments.
> >
> > /J
>