[sdiy] Patchable polyphonic synth with FM or AM transmission idea

Ben Bradley ben.pi.bradley at gmail.com
Tue Dec 25 23:22:54 CET 2018


What you're describing sounds all-digital.

It seems to me a crosspoint switch would be the thing to have on each
(analog) voice, and have them controlled by the usual microcontroller
for a polyphonic analog-signal-path synthesizer. Of course, this is a
woefully incomplete description.

On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
>
> You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
> MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
> Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won’t require you to think about transmission line theory.
>
>
> Rock & Roll,
> Oren Levy
>
> > On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> >
> > The objective is to be able to create a way for a single patch cord to
> > carry 16 voices. I'm not sure how an FPGA in itself will help me, have
> > you got any ideas?
> >
> > MADI interfaces are prohibitively expensive.
> >
> >> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
> >>
> >> I think you’d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
> >> If you just want to share audio and don’t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
> >> You’d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
> >>
> >> Rock & Roll,
> >> Oren Levy
> >>
> >>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
> >>>
> >>>
> >>>> transmission. In a 16 voice system, at about 5 output functions per
> >>>> module, and 12 modules, you can easily use up ~1000 of those, which
> >>>> drops the price to $4. I was wondering what everyone thinks about this
> >>>> sort of scheme.
> >>>
> >>> So there's $4000 worth of just one IC in a single complete polysynth?
> >>>
> >>>
> >>>
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