would this be interesting?

Kyle Farrell orb at ee.washington.edu
Fri Jan 10 05:30:59 CET 1997


Hi-
I'm trying to come up with an idea for a monosynth for a senior level EE 
design project.  What I'm planning to do is the basic
osc -> filter -> amp scheme, all under cpu control.  I'm going to be 
using a CEM3379 for the filter/amp, though I'd like to try something 
unusual for the oscillator.

What i've thought about doing is having two digital oscillators and 
switch between them at audio rates.  The user could define a point where 
the output would switch from one oscillator to the other.  The 
oscillator would first output waveform "A".  Then at the point in the 
cycle where the "switch point" is reached the output would switch to 
oscillator "B" until the end of the cycle.  The next cycle would begin 
with "A" again.  Using a triangle and square wave you could get something 
like this:

"A":
    --                
   -   -              
  -     -             
 -       -            
-         -          -
           -        -
            -      -
             -    -
              -  -
               --

"B":
-----------
          |
          |
          |
          |
          |
          |
          |
          |
           ---------


output:
    --  ---
   -  - | |
  -    -| |
 -      | |
-         |
          |
          |
          |
          |
           --------------

        ^ switch point

The switch point would be modulatable by LFOs, envelopes, etc.

I tried this in Csound and it was, well, different. :) It might be nasty
with all those sharp corners on the output, but an analog filter would do
that some good.  btw- is this at all similar to how the PPG or Prophet VS 
work?

Does this seem like it would be an interesting project?  comments &
opinion are welcome :)

thanks
-kyle





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