stupid envelope follower idea

[danial stocks]

>
>Envelope followers all suffer from the ripple/speed tradeoff.
>Very low low pass filtering of the rectified output gives low
>ripple but also slugish response and vice versa.
>
>Now, could it be improved via modulation techniques?
>
>I mean if I modulate the audio with some sine carrier,
>it would at least cut down the low frequency sideband by 1/2.
>If that is rectified and filtered, I think it would perform better.
>Like AM demodulation, well almost, but without carrier
>feedtrough.
>


>When I think it to the end, it comes close to PCM sampling.
>If I were to determine the envelope with pencil and paper,
>I'd try to connect the peaks with straight lines as first order
>approach.
>
>?

I presume you mean use an ultrasonic sine carrier? ie like an AM radio 
signal.. yep, you could rectify and filter this quite nicely to get an 
accurate representation of the audio wave as a DC out... but I dont know if 
you really want that..if you want a DC level rather than some audio waveform 
modulating the filter then you going to have to still have some longish 
filter lag to join up the peaks of the demodded audio wave form.,. still 
going to end up being the ripple / decay tradeoff.. attack can be made 
fairly independent of this problem tho without needing complex modulation 
etc,.. sounds like a big amt of extra circuits to make, dont know if theere 
would be any real gain?
Cheers,
Dan
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