stupid envelope follower idea

[danial stocks]

This all sounds like far too much extra circuits for perhaps only a really 
small gain in performance...  maybe not even a gain in performance.. 
personally, I'd stick to a 1/2 wave precis rect, separate res for atk & 
decay... then you could tweak these parameters separately, or even have pots 
for user control... this sys does have a rather hi o/p impedance, so needs a 
op amp buffer.. but still, 2 op amps simplicity and it works.. after all, in 
the design of the effect, you dont really need ultra precision math 
necessarily, you just need to make it pleasing to the ear and have good 
tweakability...[in the music shop.. oh yes, the envelop filter delux.. it 
has fourier transform envelope calculations for high precision dynamics 
tracking... stoned guitarist scratches head.. but will it sound good if I 
play hendrix ?]
Cheers,
Dan

>
>Yes, as I said, multichannel will loose phase information.
>Nevertheless though math does not work, it may work
>in real life? Perhaps the hearing system will not bother?
>

>:::
>:::Message text written by Martin Czech
>:::>:::Imagine splitting the input signal into three bands with three
>::::::envelope detectors:
>::::::  20 to 80 Hz, slow envelope detector
>::::::  80 to 320 Hz, medium envelope detector
>::::::  320 Hz and up, really fast envelope detector
>::::::
>::::::And summing the results.  If the input signal has no content below 
>320
>::::::Hz, you've got a really fast envelope detector.  If you happen to 
>play
>::::::one of the two lower strings on the guitar, the really fast envelope
>::::::detector catches the harmonics from the initial transient and the
>::::::medium speed envelope detector predominates after that.  Only for low
>::::::frequency inputs does the slower envelope detector come into play.
>:::
>:::Ok, I have to think about that. I guess 6dB/oct filters would do.
>:::In that case a highpass could be derived from the lowpass at the same
>:::edge (you know, in the way frequency splitters were once proposed).
>:::I guess that a sweeping sine then would give a flat envelope, as it 
>should.
>:::<
>:::
>:::Hi Martin:
>:::
>:::One problem with this approach is the various band filters are bound to
>:::have different group delay times, so waveform peaks passing through the
>:::filters may not line up timewise afterward.  Since harmonics of the 
>input
>:::signal will not coincide after passing through the band filters, they 
>will
>:::not add up algebraically, and you will then detect an envelope that will
>:::have a different shape than the original signal had.  This wouldn't 
>happen
>:::with sine waves, but it likely will with harmonically complex signals.
>:::
>:::Terry Michaels
>

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