[sdiy] Ideal polyphonic digital reverb

[Michael E Caloroso]

After years of experimentation I have concluded that a polyphonic
synth needs both reverb and at least a pair of delays that can be
modulated.

Reverb alone was never enough.
Modulated delays alone was never enough.

I had really liked my Korg SDD-3300 triple digital delay for synths,
which can be configured in any series/parallel/cross-coupled
architecture you can dream of.  This gets better modulated delays than
multi-effect boxes.  Then I saw a spare output and two spare inputs on
the 3300, so I hooked my Lexicon PCM60 digital reverb up to it and
that was the magic combination I wanted.

Using the 3300 I can route direct signal to reverb, then process the
reverb tales with the 3300.  Or reverb in parallel with delays.  Or
series.  Add predelay to the reverb send.  Or multiple predelay each
to different delay times.  World of sounds with this combination.
Enough that I built seven sets of these for my synths for independent
processing.

MC

On 3/22/21, cheater cheater <cheater00social at gmail.com> wrote:
> let's enumerate some of the possibilities:
>
>
> voice 1: vco1 -> (a1) -> vcf1 -> (b1) -> vca1 -> (c1)
> voice 2: vco2 -> (a2) -> vcf2 -> (b2) -> vca2 -> (c2)
> ...
> voice n: vcon -> (an) -> vcfn -> (bn) -> vcan -> (cn)
>
> at a1, you want to have one of a few things:
>
> (i) a convolution engine that takes the output of vco1, applies an IR,
> and puts it into the input of vcf1
> (ii) same as (i) but the input is all vcos (1..n) and the output is vcf1
> (iii) same as (i) but the output is all vcfs (1..n)
> (iv) same as (i) but the input is the last few notes you played in
> decreasing order: 1/2 * the vco from the most current note + 1/4 * the
> vco from the previous note + 1/8 * the vco from the note previous to
> that etc
> (v) same as (iv) but you do that with the outputs
> (vi) same as (i) but there's also input from b1 or c1
>
> then you want the same topology at b and c
>
> They're all obviously going to have different results and different
> applications.
>
> And obviously you can think about all sorts of dsp in here, not just
> convolution, and when it comes to convolution, then not just reverb.
>
> On Mon, Mar 22, 2021 at 7:03 PM Mike Bryant <mbryant at futurehorizons.com>
> wrote:
>>
>> Thought I'd change the topic name as we're definitely moving away from
>> cheap.
>>
>> So given a polyphonic synth with unlimited voices and unlimited budget,
>> what should the structure of an ideal reverb system look like ?
>>
>> Once there's a consensus I'll try coding it into my digital synth.
>>
>> _______________________________________________
>> 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
>