[sdiy] patch panel concept

[John Mahoney]

I'd like to get some thoughts on an alternative to an the EMS-style 
matrices like this one:
	http://cgi.ebay.com/EMS-16-x-16-Matrixing-Panel-Serge-Buchla-MOTM-Moog_W0QQitemZ110058752879
I don't claim it to be fully original, as I think that somebody on 
SDIY has mentioned this concept or a similar one, but I haven't seen 
it implemented so I'd like to discuss it here.

The basic idea is to use 1/8" stereo jacks to create the matrix panel 
and 1/8" stereo plugs as the "pins". As is often done with TRS 
jacks/plugs, the jacks would be wired for send, return, and ground. 
(Tip=send, Ring=return, Sleeve=ground?)

Meanwhile, a pin (plug) could simply connect the send and return 
signal to create a hard connection. Or, a pin could be wired 
internally as a voltage divider so that it makes an attenuated connection.

The jack returns would be wired in rows to summing amplifiers or 
buffers. This is why attenuated or unattenuated connections could be 
made. The inputs to send busses could also be buffered through 
inverting amps. Thus, signals are fully buffered in and out but 
there's ultimately no signal inversion.

You could build a trimpot into a pin. Or, a pin could make be used to 
make a cabled connection to a pot -- perhaps you'd have a row of pots 
or mixers next to the matrix just for this purpose.

Using such a patch bay, you could use standard synth modules sort of 
like a Synthi, which seems like a cool idea to me.

Is there anything wrong with this idea aside from the fact that it 
would require a lot of jacks, perhaps a lot of drilling (unless you 
can find the right pre-perforated material, which is quite possible), 
and a lot of soldering?

One could even take a Jim Patchell approach by making a PCB board for 
each row or column, include the input or output buffer circuit, etc...

Discuss! (Please :-)
--
john