GZIFCAK.NET

WARNING: THIS PROJECT CAN BE EXTREMELY TIME-CONSUMING AND FRUSTRATING (for me). THIS IS NOT AN EXHAUSTIVE SET OF INSTRUCTIONS, ONLY AN INTRO TO WHAT'S INVOLVED. IF YOU DON'T FEEL COMFORTABLE PORING OVER THE SCHEMATIC TO TROUBLESHOOT YOUR WORK, PLEASE DO NOT ATTEMPT THIS PROJECT.

i added pitch knobs for each of the sounds in my 707. the ones that share volume sliders also share pitch knobs, and the ride and crash have a single pitch control as well. i think the sounds are 6 bit so it sounds all gritty and industrial when you pitch them down. it's not a simple mod, however:

1. build nine 555 (the cmos version) oscillators. these are the new clocks for the sounds. i initially tried to just use a single hex inverter chip for the clocks, but there was too much interaction between the frequencies of each oscillator. if you wanted to simplify the project, you could probably just build 3 oscillators to control multiple sounds; i think there are 3 different sample rates.

2. very carefully disconnect pins 56, 57, and 59-64 of ic30 from the circuit board, or find some way to cut through the traces that go under the (surface mount) ic. i ended up slicing through the board with an exacto blade.

3. solder the outputs of the 555 oscs to the pins. this part is difficult because the pins are small and close together.

-structural integrity is extremely important here. if one of the pins breaks off, no more drum sound. it's best if you can have the pins soldered in their original places rather than sticking up in the air with the wires attached.

4. TEST.

5. find all of the connections between the original pins and the other circuitry that were severed when you cut the traces, and reconnect them to the original clocks. this part took the longest for me. you have to examine the schematic and find the stuff that gets the clock signals. it sounds distorted and bent without these connections, and some sounds may disappear.

6. mount the pots.

or you could just go and sample its sounds and tune them up and down that way, but that would be easy. also, i tried connecting the oscillators to the pins while they were still connected to the circuit board and got all kinds of crazy noises that sounded way better than my rom-scrambling bends. it was like pitching the sounds and adding tones and messing with other circuitry that was also connected to the clocks.