[sdiy] Bus for digital patching of synths

[cheater00 .]

On Fri, Nov 8, 2013 at 2:45 PM,  <rburnett at richieburnett.co.uk> wrote:
> I think Paul Maddox played about with the idea of a digital modular synth
> some time ago, (appologies if my memory serves me badly!)

I think I've never heard of this. Has anyone more on this topic?

> The only thing i'd add to what has been already said, is that high-speed
> digital audio signals like I2S contain frequencies well up into the MHz and
> can be quite finicky about PCB layout, connections, and in particular the
> impedance matching and termination at the ends of the cables.  Whilst you
> can probably send a 10V pk-pk analogue sawtooth down a rusty old 1/4" patch
> cable with a dodgey screen connection at one end, you're unlikely to be able
> to get away with that for a high-speed digital link without the waveform
> getting trashed.  So you might need more expensive cables and connectors
> that present a more controlled RF impedance to the digital signals flying
> down them.
>
> -Richie,

That's true - it would be very difficult to perform actual physical
digital patch cords. However, the idea isn't to use digital signals in
patch cables, though, only to have a digital back plane which can be
used.

The front panel might have analog connectors carried out for when
digital isn't good enough (feedback, fast transients, you name it)

To keep things cheap, look at the PC business which gives us a lot of
inexpensive card connectors perfectly suited for high-speed data. PCI
or PCIe come to mind.