[sdiy] Bus for digital patching of synths

[Tom Wiltshire]

On 9 Nov 2013, at 11:16, Florian Anwander <fanwander at mnet-online.de> wrote:

> Hello
> 
> On 08.11.13 11:42, cheater00 . wrote:
>> The question is
>> what bus is right.
> The question is not "which bus", but "which protocol". The bus will be always serial.
> 
> Florian

There's still a question over which bus - there are one wire, two wire, there wire and four wire serial buses. But yeah, serial is going to be the answer.

But that's not my real cause for concern.

I'm not sure I'm convinced that there's any need or any point to the proposed device. Essentially it's a big pile of digital patch cords, right? ADC at one end, DAC at the other, and digital routing in the middle. If that's all it does, it seems to me that Brian W is completely right - CMOS crosspoint switches are a much simpler way to do it. You get all the programmability, since you'll need a uP controlling the switches, but all the signals stay analog, and you avoid problems with DACs tending to either be good for DC voltage accuracy, or good at audio rates, but rarely both.
On the other hand, if you're going digital, why have more than a few specialised analog processing modules. You could do the processing or sound generation with digital modules and avoid the need for more ADCs - just send the digital signals straight to the bus. There are plenty of digital oscillators and digital modulators on the market, and we can imagine the same units with a digital output.
It seems to me that instant patch recall is the potential "killer feature" here, and what's proposed doesn't offer that, or not without a lot more work, anyway. Without that, it seems like an awful lot of technology to throw at a simple problem.

2 cents,
T.