30 years later...

Christopher_List at Sonymusic.Com Christopher_List at Sonymusic.Com
Thu Oct 31 16:14:06 CET 1996

  >> isn't
  >> there anything else that can be done to get some 'alternative
  >> (other than using ADSR and LFO modulation)? i mean, i'd much rather
  use the
  >> 4 waves than sampled waves, but isn't there anything that's been done
  to get
  >> some more timbral variation lately?

  > The PPG Wave and Prophet VS were attempts at doing this, albeit digitally.

  Let's not forget the various "pseudo-digital" waveforms that you can do
  1. Stepping a sequencer at audio frequency. A four or eight step
  sequencer, with one or two rows, dedicated to a task like this (i.e. no
  internal clock, no up / down, etc) would be super easy to build -
  basically just some pots, a 4017, and an op-amp or two...

  2. Stepping through eprom values using a VCO'd square wave and a counter.
  This guantees the waveshape will always be the same.

  3. Scott Gravenhorst's "Complex Waveform Generator" that uses XOR
  feedback logic

  While the PPG and ProphetVS use method 2 - as far as I know, they do it
  digitally, not using a VCO to drive the circuit. Therefore, it's safe to
  say that if you're looking for any of these methods in an actual
  production synth, you won't find them.

  More stuff to think about;
  I always thought it would be cool to stack up four VCOs and have them
  hardwired to be at different intervals relative to one another and have
  volume settings for each one - so that you could have instant partials.
  There'd only be one set of controls for all the VCO's, and there'd be one
  set of the usual sine/tri/saw/pulse outs. The cost in MAT-03s would make
  this one expensive VCO!

  As I mentioned a while ago, a great method of getting new wave shapes is
  to use a VCO (at audio frequency) to;
  1. X-fade between two other VCOs (or a VCO and the same VCO filtered)
  2. Control the CV on "Timbre Modulator #2" - the full wave-rectifying
  x-fade thing.

  Lastly, it would be really easy to build some kind of x-fade or flip-flop
  or counter into your VCO so that you had an output wave form that came
  out as half square then half saw then half tri or some combination of the
  above (which I guess is what you want - everything done at the VCO level
  - no other circuits). Though this would color the sound, but I don't
  think it would change it too drasticly.

  What sort of a waveform would you like to see - outside of a sample? Take
  the Waldorf uWave - they put all kinds of different waves in there - but
  most of them sound very similar (or the same) - until you filter them or
  mix them - so why bother?

  - CList

  ps - what I'd like to see is a wave form that goes <backwards>
  - so it would look like this on the scope;
  - :)

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