[sdiy] Best & fastest envelope follower schematic.. anybody ?

[Martin Klang]

Is that analogous to using a Hilbert transform (to get the analytic 
signal) to calculate the envelope? It works perfectly on continuous sine 
waves, and I believe it is used to extract amplitude modulation from a 
carrier wave. But not so good for audio.


Martin


On 16/12/2021 12:29, mark verbos via Synth-diy wrote:
> 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 
>> <mailto:tom at electricdruid.net>> wrote:
>>
>>
>>> Begin forwarded message:
>>>
>>> *From: *Mr&MrsAccount <hbissell at wowway.com <mailto: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 
>>> <mailto: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 <mailto:tom at electricdruid.net>>
>>>     *To: *Mike <mbryant at futurehorizons.com
>>>     <mailto:mbryant at futurehorizons.com>>
>>>     *Cc: *rburnett at richieburnett.co.uk
>>>     <mailto:rburnett at richieburnett.co.uk>
>>>     <rburnett at richieburnett.co.uk
>>>     <mailto:rburnett at richieburnett.co.uk>>; synth-diy
>>>     <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>>
>>>     *Date: *Wednesday, 15 December 2021 7:05 AM EST
>>>     *Subject: *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 <mailto: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
>>>     <mailto:synth-diy-bounces at synth-diy.org>] On Behalf Of
>>>     rburnett at richieburnett.co.uk <mailto:rburnett at richieburnett.co.uk>
>>>     > Sent: 15 December 2021 11:21
>>>     > To: Tom Wiltshire
>>>     > Cc: synth-diy at synth-diy.org <mailto: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,
>>>     >
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>>
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