Monday, April 2, 2012

Circuit Bent Casio PT-87

Modified Casio PT-87

Great vintage keyboard from the 1980's with some very interesting modifications.  This one does not have the traditional bends in the circuit.  Because of the chips used to make this keyboard, the bends I found seemed boring and did not produce an interesting variation of output signal/sound.  So I decided to keep the design effective and

Modifications made to this instrument:
  • LFO, with Hi and Low frequency settings
    • Frequency control
    • On/Off switch
    • LFO Shape and Depth controls 
  • Pitch control
  •  Filter
    • Frequency and shape control
    • True Bypass switch
  • 1/4" Mono output jack







Short Demo Video:

Audio routed to my Eurorack Pro -> Computer.  No other effects used.

5 comments:

  1. Great unit!
    do you know if there's some possible glitching bend on this one?Can't find much of diagrams on the net...
    thx

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    Replies
    1. Thanks!!

      Unfortunately not many bending options for this unit. Looking at my notes, I did not make reference to good bend points for glitches. I do remember spending some time carefully poking around, but in the end added features instead. Try looking up the IC's and try incorporating bends with them. Sometimes you can make a filter with an OP amp or add resistors and/or caps to alter sounds, glitches etc. Sorry not much to share. good luck!!

      -FrankenMusik

      Delete
  2. I wonder if i can modify a brand keyboard CASIO PT-87 I have. I would change the DC of 7.5 watts per connector like akai mpk mini usb to use as midi, put 2 wheel's one for the pitch and the other modwheel in the part where it was a ROM cartridge, and I would also like can form chords. Bone that keys can be pressed at once. You can help me?

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  3. Hi , can you tell me what lfo circuit did you used and what filter ? Thanks , Alex .

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