[sdiy] Interesting article on top octave generators.

[Donald Tillman]

On Dec 26, 2024, at 8:42 AM, The SynthiMuse via Synth-diy <synth-diy at synth-diy.org> wrote:
> 
> I guess there's a big overlap between synth-diy people and visitors to Hackaday but just in case anyone is interested; good article ( with some links to other articles embedded ) on Top Octave Generators.
> 
> https://hackaday.com/2024/12/24/the-mystery-of-the-messed-up-hammond-x5/

Interesting.

There *must* be some spare MM5833's out there.  At the very least from dead Hammond X5's or other organs that have been parts'd out.  Or maybe a different TOG chip could be found and adapted.

But y'know... I can't help but think that it's downright weird to replace a TOG chip with a computer.  Of course if it works, it works; certainly.  It's just that the technological limitations of the day were so fundamental to the very nature of these instruments.

If it was me, I would have directly emulated the chip with, say, 6 CD4040's and some diodes.  Which is probably exactly what the Hammond engineers did while they were building prototypes and waiting for the TOG chips to be delivered.

The top-octave-with-dividers approach to electronic organs has been around since the Baldwin Model 5, introduced in 1946.  That's vacuum tubes, of course, and with the top octave being individually tuned oscillators. 

Many years ago I pointed out on synth-diy that, plugging the numbers in, the TOG chips had roughly double the error of the Hammond tone wheels.  And that I found that disappointing; all this technological development for significantly less accuracy.  Of course that's because tonewheels have integers in both the numerator and denominator while TOG chips are stuck with just the denominator.

  -- Don
--
Donald Tillman, Palo Alto, California
https://till.com




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