Roland TR-909 tune+decay mods, firmware upgrade

Posted by in equipment, KORN HARDCORE CUSTOMS, mods & repairs, News, Studio

Duration 10h for Mods: 600€ +Parts and postage (german clients +19%)

Spring 2020 new full length video!

Completely reverted the previous work. NOW it feels like my very own 909. Notice that signatures from Jeff Mills and Juan Atkins that i was lucky enough to meet during gigs.

So the final list of modifications is almost endless since the great nava extra 9 project and Robin Whittle documented a lot of other stuff that i needed to try out. I was actually ok with it now to not being able to switch every mod on/off. But you can dial in the stock values still. Plus i needed that replica knobs that really look great on the machine now. Was some extra work to fit in the support boards for the d-shaft knobs but totally worth it.


Anyways, here is the list:

-BD Pitch R59 (100k lin + 10k)
-BD Tune Depth R28… (220 kB+Trim)
-BD Overdrive R52 (10 k lin + 1k)
-BD Tune Range (C9 1uF, R21 1k R57 10k paral.)
-BD Decay Range (C8 1uF parallel)


-SD Tune Range extended R284, R287 (4,7k 47k prallel)
-SD Tone Range extended (Noise Decay) R254=100k: 10k replace or 10k parallel
-SD Snappy Boost R294 (22k parallel) Trimmer: boosted the mix level of the output of the Snappy pot (13.4k instead of 47k, leading to 3.5 times the signal level, which is about 10dB)
-Switch Snare Decay exponential C68 is removed, which eliminates the 24 ms flat start to the envelope

-Tom Tune Range extended R112 10k Original parallel 4,7k and R113 68k orig parallel ca. 30k

-RIM Tune R414 (1M rev log )
-HH Tune R492 (22k lin + 6,9k)

-CLAP Tune R207 (500k lin + 13,7k)
-CLAP Noise (10k lin) TM near R494
Tune R492 (22k linear +6,9k) 50k

Cassette Slot: 
-Rim tune pot (r414) 1m log
-switch on/off
-clap tune pot 500k
-switch on/off

-BD Diodes
-Snare bleed!!! Q47 VCA (hi passed noise) almost gone, thanks Robin Whittle!!!
-Master Volume crackle => vaseline:)
-BD Tune Depth and Tune on one switch

Resources: … Matma?dl=0

IMG_5085 IMG_5084 IMG_4619 IMG_4621

Summer 2013:

Modded this little Roland TR-909 together with Claudio of discrete-audio-solutions back in the days. All mods are switchable to „stock“ sound (except clap noise).

-BD-Tune, BD-Overdrive, BD-Decay Range Extension Switch
-Clap Noise Volume
-Rimshot Pitch variations switch
-Hihat Tune


Also exchanged the eprom to the latest firmware (V4) with stable MIDI timing. Thanks to curetronic for the steady desoldering-hand:)