GZIFCAK.NET

Roland TR-909 modifications

kick:

• -extended decay range
• -trigger on/off switch (allows the trigger line to be toggled for easy muting of sound without cutting off decay)
• -pitch, tune depth, overdrive (thanks to colin fraser)

snare:

• -trigger on/off switch
• -noise low pass filter frequency
• -vco 2 extended decay switch
• -diode overdrive switch
• -pitch envelope switch - normal, off, extended depth

toms:

• -trigger on/off switch
• -pitch envelope switch - normal/off
• -vco 3/noise decay
• -noise level

rim shot:

• -tune (pitch knob for 2 of the 3 tones)
• -trigger on/off switch

clap:

• -reverb amount
• -pitch
• -width (controls spacing of the individual claps)
• -length (controls how long the claps last; along with the width control it determines the number of individual claps)
• -trigger on/off switch

hi hats:

• -sample swap switch (triggers closed sample with open decay on open hits, and open sample with closed decay on closed hits)
• -logic bypass (uses same sample for open and closed, swap switch chooses sample)
• -trigger on/off switch
• -tune (thanks to colin fraser)

crash and ride:

• -lower pitch range switch
• -trigger on/off switch

global:

• -noise frequency - detunes the shift register clock to make low frequency noise with audible clicks. affects the snare snappy, toms, and clap.

schematics and circuit analysis