Top octave dividers: A few ideas

Sean Costello costello at seanet.com
Fri Nov 5 20:05:39 CET 1999


Rene Schmitz wrote:

> Another idea would be to use twelve fixed frequency oscillators, like two
> 40106s with caps + resistors. As was pointed out here, these CMOS schmitt
> triggers are quite temperature stable. Would allow a precise equally
> tempered scale. Tunes like a piano. Output is not a 50% squarewave, but
> this doesn't matter as you'll use dividers anyway.

This is the way that older organs worked, such as the Farfisa and Vox (actually,
they usually used 13 oscillators - an additional oscillator was needed for the
bottom C key, for some reason). Even if the fixed frequency oscillators weren't
perfectly temperature stable, the resulting sound might be more "lively" than a
keyboard based on one master oscillator. Slight temperature variations would
result in intervals that aren't perfectly in tune - but since equal temperment
isn't perfectly in tune to begin with, the sound of this would probably be
pretty nice.

Sean Costello



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