[sdiy] Ideal polyphonic digital reverb

[cheater cheater]

Could even add more delay lines and additional I/O for eg inserting an
analog filter into feedback loops... nothing's stopping you with
today's hardware...

What sort of feedback processing is there on the SDD-3300? No one
mentions anything like a filter, or ducking, or compression.

On Wed, Mar 24, 2021 at 2:10 AM cheater cheater
<cheater00social at gmail.com> wrote:
>
> Since the SDD-3300 is all digital, it really does not sound like a
> very sophisticated algorithm - what's stopping someone from making a
> competent clone on an arduino or a small microcontroller with a few
> megs of ram?
>
> On Tue, Mar 23, 2021 at 6:02 AM Michael E Caloroso
> <mec.forumreader at gmail.com> wrote:
> >
> > SDD-3000 is a single digital delay, no MIDI
> >
> > SDD-3300 is three digital delays with MIDI.  Complete description on my webpage:
> > http://analoguediehard.com/studio/effects/korg_sdd-3300/index.html
> >
> > Both are programmable.  Another difference is the LFO: four waveshapes
> > are available on the SDD-3000, while the SDD-3300 is triangle
> > waveshape only but each delay unit has two LFOs and the LFOs between
> > delay units can be phase offset.  That last feature is important for
> > stereo modulated delays that do not cancel in mono.
> >
> > MC
> >
> > On 3/23/21, cheater cheater <cheater00social at gmail.com> wrote:
> > > can you both tell me the difference between an sdd 3300 and an sdd 3000?
> > > thanks.
> > >
> > > On Tue, Mar 23, 2021 at 3:41 AM Michael E Caloroso
> > > <mec.forumreader at gmail.com> wrote:
> > >>
> > >> Want more intriguing?
> > >>
> > >> MC
> > >>
> > >> On 3/22/21, James Coplin <james at ticalun.net> wrote:
> > >> > As someone with 3x SDD-3300s sitting here this intrigues me mightily.
> > >> >
> > >> > James R Coplin
> > >> >
> > >> > On Mar 22, 2021, 8:56 PM, at 8:56 PM, Michael E Caloroso
> > >> > <mec.forumreader at gmail.com> wrote:
> > >> >>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.
> > >> >>>>
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> > >