[sdiy] Best & fastest envelope follower schematic.. anybody ?

[Jean-Pierre Desrochers]

Precognitive… Interesting.
This can be done easily with a PIC reading a moving input voltage
then output the computed results on its DAC for example a bit later
according to where the actual incoming waveform is heading (plus or minus). 

 

De : Paul Perry <paulfrancisperry at gmail.com> 
Envoyé : 15 décembre 2021 16:44
À : Benjamin Tremblay <btremblay at me.com>
Cc : Jean-Pierre Desrochers <jpdesroc at oricom.ca>; Synth-diy at synth-diy.org
Objet : Re: [sdiy] Best & fastest envelope follower schematic.. anybody ?

 

Unless it is precognitive, an envelope follower must have lag.

Of course, if you are not working live, you can play the track backwards and process that.

It is illustrative to place a piece of card over a drawing of an audio waveform, and gradually reveal more of it.

Then you can appreciate what you are asking the follower to do.

There are no perfect followers, but sometimes there are ones that are useful for a particular application.

 

paul perry melbourne australia

 

On Thu, 16 Dec 2021 at 02:35, Benjamin Tremblay via Synth-diy <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org> > wrote:

I lost all interest in envelope followers when I tried out some designs and observed the lag. 
These are mostly “envelope smoothers” and most are barely any better than an old incandescent vactrol attenuator circuit used in FM broadcast.
They mostly just drive non-musical effects under the category “something weird happens when I play my guitar”.  Pre-filtering the audio probably helps but there’s no guidance on best all-round EQ.
Only The Residents got much mileage out of envelope followers over the years.

> On Dec 15, 2021, at 10:05 AM, Jean-Pierre Desrochers <jpdesroc at oricom.ca <mailto:jpdesroc at oricom.ca> > wrote:
> 
> Hi Tom,
> 
>> Harry Bissell's envelope follower is well thought of for its combination of speed and accuracy.
>> https://modwiggler.com/forum/viewtopic.php?t=109067
> 
> This is a very clever project and neat design.
> But still too much ‘lag’ on the falling edges incoming signal.
> So far.. a PIC would do best with least components..
> Hmmmm...
> As usual.. Thank you for you good suggestion anyway !
> JP
> 
> 
> De : Tom Wiltshire <tom at electricdruid.net <mailto:tom at electricdruid.net> > 
> Envoyé : 15 décembre 2021 04:08
> À : Jean-Pierre Desrochers <jpdesroc at oricom.ca <mailto:jpdesroc at oricom.ca> >
> Cc : Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org> 
> Objet : Re: [sdiy] Best & fastest envelope follower schematic.. anybody ?
> 
> Hi JP,
> 
> Harry Bissell's envelope follower is well thought of for its combination of speed and accuracy.
> 
> https://modwiggler.com/forum/viewtopic.php?t=109067
> 
> It's a good circuit, but pretty complicated, especially for an effect pedal design. So like you, I thought "PIC!", and had a go at implementing it in firmware.
> 
> The round-robin three peaks detectors are easy enough. Doing the output filtering is more demanding on a chip with no multiply, but I managed it by being choosy about the filter coefficients and keeping things binary friendly. The end result was pretty good and used a little PIC to the maximum extent.
> 
> HTH,
> Tom
> 
> ==================
>       Electric Druid
> Synth & Stompbox DIY
> ==================
> 
> 
> 
> 
> On 15 Dec 2021, at 01:34, Jean-Pierre Desrochers <mailto:jpdesroc at oricom.ca <mailto:jpdesroc at oricom.ca> > wrote:
> 
> Hi all,
> I’m looking for a fast and accurate voltage follower circuit.
> There are plenty of them on the web to build but they all
> suffer of inaccuracy and lag on the final DC output (final stage of low pass to smooth off the incoming peaks).
> The incoming voltage will be a varying 0 to +/-5v peak.
> I thought about implementing a solution using a small PIC with ADC/DAC
> but even if these micros are very cheap this solution would be overkill.. would it be ?
> So far the available circuits have too much lag on their DC output.
> (The envelope takes too much time to get back to zero after a fast incoming peak)
> Any known & reliable circuits ?
> JP
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