TR-606 hi hats oscillator running

Question

Quick question, does anyone know the exact timing for the 6 square oscillators that make up the hi hat sounds on the TR-606?

Answer 1

No one knows (well, not exactly, except for one particular unit on one particular day). It's easy enough to find the schematics, but they're CMOS Schmitt trigger oscillators, and the Schmitt thresholds, and hence oscillator frequencies, varied widely from chip to chip, and therefore from unit to unit. OnSemi's datasheet for a new 4584 gives 4:1 range between the maximum and minimum hysteresis range, and hence a 4:1 variation in potential oscillation frequency for the same RC time constant.

They're in the vicinity of 1Khz-3KHz, though, and obviously aren't very critical. 330K and 10nf is a 3ms time constant, so 3ms up and 3ms down for a full 5v hysteresis. The oscillator will be around 4x faster with a 1.2v hysteresis and a 5v supply, and 4 times that if the hysteresis is 0.3v. And that's without the 5% or 10% tolerance of the RC constant.

http://machines.hyperreal.org/manufacturers/Roland/TR-606/schematics/roland.TR-606.schem-6.gif

https://www.onsemi.com/pdf/datasheet/mc14584b-d.pdf

Answer 2

I'm also trying to find this out, which is how I came upon your question. I've had no luck yet with the 606 hats, but I have found a page which shows the 4 oscillator tunings of the quite similar Boss DR-110 hats - as well as their respective VCA decay times (which are all different, interestingly).

http://www.sdiy.org/richardc64/new_drums/dr110/dr110a1.html

Anyway it may help, and I'll let you know if my searching comes up with similar for the 606 (or 808, which as far as I know is the same as the 606 but with added white noise).

Good luck - and please let me know if you do find them!