4046

[Don Tillman]

   Date: Fri, 22 Nov 1996 10:08:26 +0200 (EET)
   From: Kimmo Koli <kimmo at clara.hut.fi>

   Phase detectors are close relatives to ring modulators, some cheap synths
   even use an XOR and claims it to be a ring modulator (close, not but not 
   quite...). So why not use the 4046 oscillator a stand alone oscillator. Its
   signal is then fed to the phase comparators with an external signal. Then
   you have two different weird pulse trails as an output. And every synth
   freak can make a use of that...

While an XOR gate would be a miserable implementation for a general
purpose ring modulator synth module, it's completely fine for the
special case where the ring modulator inputs are guaranteed to be
square (or pulse) waves.  And for this example, since the VCO is from
the 4046, you're halfway there.

The ARP Odyssey uses the XOR gate approach on the assumption that for
a performance-oriented lead synth product you really don't need a
general purpose ring modulator, just some ring modulator-like sound to
be used every once in a while.  So it has an XOR gate on the VCO
square/pulse outputs.  They've got a point: if you're going to have a
proper ring modulator you really should have the ability to patch all
sorts of things (submixes, etc.) into it.  And on a small performing
synth that's just not going to happen.

  -- Don