[sdiy] Best & fastest envelope follower schematic.. anybody ?
hbissell at wowway.com
Thu Dec 16 19:52:50 CET 2021
Thanks Mark. I was thing about the SPV-355 Pitch to Voltage Synthesizer as well. The trick here is that the input waveform has been made roughly sinusoidal before we reach the "dome filter". This dome filter is essentially a series of phase shifters which the highest peak sent to the output. In some ways it is similar to my approach. It does not work unless the input is a sine wave. Send a wideband signal into it nd you get junk.
From: mark <synth-diy at synth-diy.org>
To: Tom <tom at electricdruid.net>
Cc: synth-diy at synth-diy.org <Synth-diy at synth-diy.org>
Date: Thursday, 16 December 2021 6:35 AM EST
Subject: Re: [sdiy] Best & fastest envelope follower schematic.. anybody ?
The Roland SPV-355 Pitch to Voltage Synthesizer sends the signal through a simple “dome filter” or 90 degree phase shifter before the follower. This allows the 4 phases to be diode OR’ed together and fill in the space between the umps in low frequencies. I have tried it in my pitch to voltage experiments and it didn’t help too much, but it is an interesting idea to get some frequency-decay independence. Mark
On Dec 16, 2021, at 1:23 AM, Tom Wiltshire <tom at electricdruid.net> wrote: Begin forwarded message: From: Mr&MrsAccount <hbissell at wowway.com> Subject: Re: [sdiy] Best & fastest envelope follower schematic.. anybody ? Date: 15 December 2021 at 15:19:38 WET To: Tom Wiltshire <tom at electricdruid.net> The worst case for the envelope follower is at the lowest frequencies, 80Hz for guitar. That is where the ripple is the greatest. If you make the filtering slow enough to filter 80Hz there is a very long tail when the input signal goes away. The normal guitar decay can be as long as seconds... but if you stop the strings if can be MUCH shorter, and the classical approach will still allow the envelope to decay slowly. The reset clock should be set to about 100Hz (not 8KHz). Its easy to filter the high frequencies and there is no benefit to the circuit for short tone bursts like in the comparison paper. The circuit is also not the best for triggering on an input signal where the lowest frequency is unknown or cannot be specified (like wideband music etc.) It is intended for something like guitar or bass. Harry Bissell
From: Tom <tom at electricdruid.net>To: Mike <mbryant at futurehorizons.com>Cc: rburnett at richieburnett.co.uk <rburnett at richieburnett.co.uk>; synth-diy <synth-diy at synth-diy.org>Date: Wednesday, 15 December 2021 7:05 AM ESTSubject: Re: [sdiy] Best & fastest envelope follower schematic.. anybody ?Some envelope generators do feature a "Decay" pot to change the time constant of the filter. Depends on the use case whether that is worth it. In a bit of studio gear where it might get used for various sources, yes, it probably makes sense. For a stompbox where the input is going to be a guitar, you have more knowledge about the signal and you can optimise the design for that. > On 15 Dec 2021, at 11:37, Mike Bryant <mbryant at futurehorizons.com> wrote: > > Why not have both fast and slow filters, and a blend pot between the two so you can find the best trade-off for the incoming signal ? > > > -----Original Message----- > From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of rburnett at richieburnett.co.uk > Sent: 15 December 2021 11:21 > To: Tom Wiltshire > Cc: synth-diy at synth-diy.org > Subject: Re: [sdiy] Best & fastest envelope follower schematic.. anybody ? > >> With such a simple filter >> there *will* always be a trade-off between speed and ripple. > > Or to put it another way... Increasing the order of the filter gives you a more favourable trade-off between speed of response and residual ripple. > > -Richie, > > _______________________________________________ > Synth-diy mailing list > Synth-diy at synth-diy.org > http://synth-diy.org/mailman/listinfo/synth-diy > Selling or trading? Use marketplace at synth-diy.org > _______________________________________________ Synth-diy mailing list Synth-diy at synth-diy.org http://synth-diy.org/mailman/listinfo/synth-diy Selling or trading? Use marketplace at synth-diy.org _______________________________________________Synth-diy mailing listSynth-diy at synth-diy.orghttp://synth-diy.org/mailman/listinfo/synth-diySelling or trading? Use marketplace at synth-diy.org
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