[sdiy] Divide down question

[Scott Nordlund]

> What about this:
> start out with a normal square divide down, and then when you're e.g.
> playing C1, then actually what is output is:
> C1+ 1/2 C2 + 1/4 C3 + 1/8 C4
>
> Each of the higher tones would have to go through a latch. That latch
> would only let through one pulse of C2, C3, etc, but it would be reset
> on C1's rising slope. Maybe this could be a little bit difficult,
> maybe not.
>
> This should give you a 'steppy' saw down, shouldn't it?
> I think the latches could also add a little bit of delay or,
> alternatively, you could add a little solenoid or cap for each of the
> partials. Then, when you press the C1 and C2 keys on the keyboard, the
> voices could sound a little bit more alive (because of the time
> offsets creating phasing)

You're describing Rademacher functions (a subset of Walsh functions).
There's no need for latches, though.  If you think of the divider 
outputs as a binary counter, and they're summed with binary weights
(a quasi-DAC), the result is an approximate sawtooth.  It's steppy, 
though, and it sounds kind of buzzy and organ-esque.  Also it's no 
good for PWM.

Plenty of organs and string synths use this, and some synthesizers too
(Korg Poly 800, Poly 61, Crumar Bit One, etc.).

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