[sdiy] Fast envelope follower circuit needed..

[cheater cheater]

On Fri, Apr 5, 2013 at 6:36 PM, Richie Burnett
<rburnett at richieburnett.co.uk> wrote:
> Hi all,
>
> A few weeks back I posted a response here recommending the OP to investigate
> using the Hilbert Transform to extract the envelope from a signal.  This was
> because I've had good results using this in some specific DSP products.
> However, Bernie Hutchins initiated some interesting off-list discussions
> about this, and he has pointed out to me several example situations where
> this method does not yield the envelope that a synth enthusiast might
> intuitively expect to see!
>
> I don't want to go into this in too much depth because the thread didn't get
> much response anyway, and Bernie has looked into this in far more depth than
> I did, some years previously.  He has kindly agreed to me including a link
> to his thorough analysis here:
>
> http://electronotes.netfirms.com/AN355.pdf

This electronote is super interesting. Summing it up: you don't want
to use the Hilbert transform for composite sounds; in any case the
low-pass filter approach is better or just as good.