[sdiy] Full wave rectifier for audio

[Seb Francis]

Seb Francis wrote:

>
> So perhaps something like the full wave rectifier circuit from 
> play-hookey.com, followed by a diode charging a cap (via the attack 
> rate pot), with the release rate pot discharging the cap.  Is that 
> what you mean by a peak detector .. diode->cap?
>
Sorry, not quite thinking straight, what I should have said was..

Full wave rectifier circuit from play-hookey.com, followed by a diode 
charging a cap, with the *hold* pot discharging the cap.  The attack and 
release pots will be post threshold comparator and will control the 
attack and release of the actual VCA CV.  (Did I mention it's not just a 
noise gate - it also has a MIDI trigger input for gating sounds - hence 
the desire to have an attack pot).

I'm also thinking the threshold comparator circuit may need to have a 
bit of hysteresis to avoid the gate chattering if there's ripple from 
the peak detector for very low frequencies at around the threshold level 
(e.g. the tail end of bass notes) .. I have to see if this will be 
necessary - maybe I can balance having a fast enough attack response 
with sufficient ripple rejection for low frequencies.  Or maybe just 
having some hold time will prevent this chattering.

Seb