Designing a Patchable Modular Synthesizer with Memory

J.D. McEachin jdm at
Sat Feb 24 08:49:05 CET 1996

On Wed, 21 Feb 1996, Mark Landman wrote:

> Some interesting thoughtsŠ I'd agree that it's important to maintain a
> visual representation of your patch, so you can see what your doing. How
> about some type of pin matrix ala Arp and Ems? Easy to scan and digitize,
> almost as good as patchcords for patching and troubleshootingŠ

Statements about patchcords being easy to troubleshoot have always amazed 
me.  I always wonder if the persons making them have ever used a 
modular, and if so, if they have more than 5 patchcords.  My experiences 
with patchcords are:

1) There's always at least one less patchcord available than you need.

2) Tracing a patchcord thru the tangle of a typical patch is a pain in 
the ass.

3) Tracing a patchcord is likely to unplug something, or change the 
connection of something (ie. to a dirty jack) and change the patch.

Patchcords have the advantage of being very tactile and immediate, but 
the advantages begin to be outweighed by the disadvantages after you have 
more than 10.

Matrices have the disadvantage of requiring a mental translation from the 
matrix to the modular panel.  Mental translation gets in the way of 

Here's my suggestion for a UI (User Interface):

Each modulation source & destination will have a momentary contact

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.  

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 
expensive for most of us to even think about using.  Here's my 
compromise, stolen from the PAIA Proteus I:

Each slider (pot if you prefer) has an LED above it.  When the pot matches
what is in patch (computer) memory, the LED comes on.  When you recall a
patch, the LED associated w/ a pot is turned off (unless the pot happens
to match the stored value), and turning a pot does nothing until you move
it to match the stored value.  Then the LED turns on.  You don't have to 
reset a pot unless you're interested in knowing its prior value.  From 
experience, this works pretty well.

Of course, the biggest problem w/ Clive's pie-in-the-sky modular is the 
switching matrix.  To build a 64x64 (what I consider the minimum useable 
number) audio/cv switching matrix w/ 80-90dB of S/N is quite a 
challenge.  I suppose you could use relays, but I'd be frightened to see 
the power bills.  Suggestions, anyone?


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