sure, i don't have any documentation but if you have specific questions i can answer them. i actually just scaled back my clap mods because i found myself simply trying to find the stock settings all the time. now i just have reverb level, reverb time, and pitch.

i compared the schem to the tama ts306 schematic to figure out how to control the pitch.

For clap tune, you have to rearrange part of the circuit to resemble other
tunable clap circuits like the Tama. On this circuit you can see that the
junction of C315 and C316 have a pot that goes to ground. The 909 also has
a resistor to ground in the clap filter, which you have to replace with a
pot, but you might also have to change the value of the feedback resistor
and the capacitors, I can't remember. It's pretty subtle, unless you
change the values by a lot, in which case you start to get drastic changes
in the resonance of the filter and a very awkwardly scaled tune knob.

To lengthen the reverb decay time, you have to make C61 bigger. For reverb
level, you have to change the level either going into or coming out of the
VCA, Q37.

As for the timing and length mods, I ended up taking them out because I
didn't find them very useful and they destroyed the illusion of a clap
sound at any settings other than normal. But those ideas came from a
description of the Amdek Handclapper circuit.

C61 is the capacitor responsible for the timing of the
reverb sound. Its value is .01uF. If you replace it with a capacitor
that's .02uF, the reverb will get twice as long. With capacitors, you can
increase the value by wiring them in parallel, which is what I did. So I
wired a switch that connects another .01uF capacitor across the contacts
of C61. I may have used a bigger one for even longer reverb, I can't
remember.

The clap timing and length mods were difficult to get right, and when
using them I had a hard time tuning them back to the original settings.
This is why I removed them. I wanted quick access to a classic sounding
clap on the 909. If I want weirder clap-like sounds I use something else,
like a synth or Nord Drum 2.

Altitude wrote:I have my secondary noise source board from the 9090 days. This gets rid of the phasing between the clap and snare if triggered at the same time

Altitude wrote:I'm in the process of putting kits for this. It will come with the shift registers and the PCB

Altitude wrote:I'm in the process of putting kits for this. It will come with the shift registers and the PCB