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

[Joel B]

3.5mm TRRRS jacks - should be able to carry 4 signals over that for a four voice patchable synth? 

https://m.alibaba.com/product/60708756554/OEM-ODM-GuangZhou-YIVO-Wholesales-Hi.html?s=p

Sent from my iPhone 

> On Dec 25, 2018, at 2:40 PM, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> 
> I want to make this work for an all-analog synthesizer, but rather
> than use crosspoint switches I want to use patch cables which makes
> things much less annoyingly complex and expensive. The thing is, where
> on a monosynth you have a single patch cable, on a patchable polysynth
> you have n patch cables, one for each voice. So I am currently trying
> to work out how to do this using a single patch cable, and frequency
> domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
> FDM, since almost all of this is analog, so I'm looking at dedicated
> radio transmitter chips. At $4 per chip, it's not so bad. The question
> is how to make the chips talk to a single medium without fighting each
> other.
> 
>> On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <ben.pi.bradley at gmail.com> wrote:
>> 
>> 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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