Designing a Patchable Modular Synthesizer with Memory

[gstopp at fibermux.com]

     How about if we keep the patchcords, but make them out of colored 
     string to symbolize the connections and preserve the visual 
     understanding of the patch? As the ends are plugged in, the uP will 
     see them occur in pairs and make the connection.
     
     Going one step further, how about adding a metal conductor down the 
     center of each string, so that the uP will see the actual electrical 
     continuity between two points and make the connection as a result?
     
     Wait, now how about if we send the *actual signal* down the center 
     conductor of the patchcords, and do away with the uP/matrix 
     altogether?
     
     Oh... sorry....tee hee....
     
     It sounds like this thread is tending towards a concept where each 
     module in a system is treated as an "object" by a supervisorial 
     processor, each object with an input set and an output set, with all 
     objects "placed" on a background of some kind of analog connection 
     matrix. Each object could contain its own "agent", whose purpose is to 
     maintain local parameters and connections, as well as presenting 
     status and I.D. information to the supervisorial agent. Inter-agent 
     communications could be facilitated by some high-speed serial bus 
     protocol like I-squared or JTAG. The LED/pushbutton UI ideas sound 
     pretty good for starters, and so does the LED/knob thing. Additionally 
     a click-and-drag graphic application for a PC could be implemented for 
     those CRT-happy users.
     
     Hardware-wise, each module would be some kind of analog function, with 
     a uP/DAC mux, a front panel with controls, and a backplane interface 
     with the datacomm channel plus the parallel analog I/O's that go to 
     the matrix. The VCA's for mod depth could be on-board, providing all 
     required patch attenuation at the destination so that the matrix could 
     be a cross-connect for full-strength signals only. Maybe there could 
     also be a serial port on each module to allow configuration via dumb 
     terminal, for things like agent I.D.???
     
     I know I've seen datasheets for analog crossbar switch chips - maybe 
     these could be employed in the patching matrix? Crosstalk will be the 
     issue here.
     
     This is sick. My brain hurts. :-)
     
     Of course this would all be conceptually perfect for complete virtual 
     implementation, but that would be, after all, "fake".
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: RE: Designing a Patchable Modular Synthesizer with Memory
Author:  "J.D. McEachin" <jdm at synthcom.com> at ccrelayout
Date:    2/24/96 8:12 AM
     
Here's my suggestion for a UI (User Interface):
     
Each modulation source & destination will have a momentary contact 
pushbutton w/ LED above it, LOCATED ON THE MODULE IT'S ASSOCIATED WITH.=20
     
To assign a mod routing, push and release the source button, then push and 
release the destination button.  This will patch the two together thru an 
internal switching matrix. =20
     
To check out the mod routings for a particular source or destination, 
simply press and hold that button for a second.  All mod points that are 
connected to it will make their LEDs blink.  Very fast, intuitive feedback. 
Visual, as opposed to mental, processing.
     
As for the pots/sliders, let's face it, motor driven ones are just too=20 
expensive for most of us to even think about using.  Here's my=20 
compromise, stolen from the PAIA Proteus I:
     
Of course, the biggest problem w/ Clive's pie-in-the-sky modular is the=20 
switching matrix.  To build a 64x64 (what I consider the minimum useable=20 
number) audio/cv switching matrix w/ 80-90dB of S/N is quite a=20 
challenge.  I suppose you could use relays, but I'd be frightened to see=20 
the power bills.  Suggestions, anyone?
     
JDM