Filter ICs and crossfade circuits

[Don Tillman]

   From: Michael Potas <michael at lake.com.au>
   Date: Tue, 25 May 1999 12:55:06 +1000

   I have noticed that most state variable filter circuits use the
   CA3080 and not the LM13600.  Do the CA3080s sound better?  

The CA3080 is often used as a Generic OTA, much like a 741 gets used
as a Generic opamp.  

Typically you wouldn't use the CA3080 because it has no noise spec or
linearization diodes.  (Much like you wouldn't use a 741; its noise
and slew rate.)  You'd use a CA3280 instead.  Or an LM13600.  

   I want to build a CV controlled crossfade circuit.  The idea is
   that I can smoothly fade between two input waveforms to create a
   single output waveform.  Hence using say Trig and square wave
   inputs, you can morph between one and the other using CV.  

Note that fading and morphing are very different.

  -- Don