Thu Jan 13 16:33:57 EST 2011

Synth requirements revisited

Stable basics.  
These are mostly about complexity and price.

  - No manual calibration (trimpots, hand matching components)
  - No obsolete or near-obsolete components
  - Digital tuning, either direct or using feedback control
  - Minimal discrete component count

Some early assumptions overturned:

  - Not allowing analog CV modulation is a bad idea. 

    While it might be a nice way to get to an incrementally working
    design, you really want to leave open audio-rate modulation of the
    filter and oscillator frequencies.  It's virtually for free on the
    analog side, once you have the exp converter working.

    Problem is calibration though: feedback calib is probably simple,
    but analog calib costs something.

  - On-line control might not be so essential for anything else than
    the oscillators.  If it's good enough for the prophet 5 and the
    mopho, 7 bits should be plenty for my little project too.  Of course, using the
    filter as an oscillator does up its requirements.

    EDIT: mopho filter cutoff does respond to more than 7 bits, and I
    believe so does the Prophet knob control.