[sdiy] modular synth "standards" (longwinded)

[Don Tillman]

   Date: Thu, 22 Feb 2001 06:57:14 -0600
   From: Grant Richter <grichter at asapnet.net>

   Music synthesizers "evolved" from the analogue computer.

And test equipment; signal generators, pulse generators, etc.  

Which suggests an interesting way to describe the design of a modular
synth.  Imagine four catagories:

  Category 1. Test equipment and analog computers.  Modules perform
  abstract math functions and were never designed to be musical
  instruments.

  Category 2. General purpose modules with no preconceptions how
  they'll be used.  A VCO could be used as either an audio VCO or an
  LFO.  Control and signal voltages are indistinguishable.

  Category 3. Modular synth with modules designed for specific musical
  applications.  Separate LFO and audio VCO functions.  A VCF would
  include audio input mixers and control input mixers.

  Category 4. Effectively a collection of guitar stomp boxes.  Each
  module performs an entire musical effect.

I like this.  It acknowledges folks who say "an analog computer is a
synth" and folks who say "a collection of stomp boxes is a synth".

Moog modules dance around between categories 2 and 3.  They use
separate control, audio and trigger signal (category 3), the VCF is
designed to be musical (category 3) but has no control or audio mixers
(category 2) so a typical use require additional mixer modules.

ARP 2500/2600 modules dance around between categories 2 and 3 the
other way.  Common audio and control signals (category 2), but each
module as extra musical features like the inputs with varying
sensitivities to make modulation easier (category 3).  (The ARP 1047
"Multimode Filter/Resonator" module from the ARP 2500 is an exteme
example of extra musical features.)

Some modules are entirely category 4; a spring reverb module is pretty
much always going to be used as an effect at the end of the chain.  

  -- Don

-- 
Don Tillman
Palo Alto, California, USA
don at till.com
http://www.till.com