Circuit Bent Roland DDR-30

I really love the sound of the Roland DDR-30 Digital Drum module as is.  Overall it has a hell of a dirty bite to it, and the super deep snare and tom sounds have turned up in several of my compositions through the years.  However, since the module itself has no internal effects or sequencing, it is pretty useless once you sample it.  I strongly considering selling it recently until I read that it might be a good candidate for circuit bending.

There is a ton of information online about circuit bending, so I won’t try to rehash it here.  Suffice it to say that the point of circuit bending is to short circuit existing hardware in musically interesting ways.  This is not without its risks, and you should be willing to loose your hardware in the process of modifying it.  Also, extra care should be used when modifying a 120V powered circuit like this one.  ALWAYS check the voltage of the points you’re working with before messing with them, and NEVER fool with the power supply section of the board.  There is some great information here on what to look for when circuit bending.

Disclaimer: proceed at your own risk.  I take no responsibility if you damage your hardware or body doing this.

Inside the DDR-30, the chips of interest are the three large ROMs on the main (lower) circuit board.  One handles the toms, one the snares, and one the kicks.

Three ROMs used in this project.

I decided early on that I wanted a patch bay so that no bends were hard wired.  After some experimenting, I determined that most of the pins on the chip change the sound in some way.  Instead of agonizing over which to use, I just ran wires to each of the chips’ pins.  This took awhile, as there were 28×3 pins and I was trying to keep each wire tagged with its respective pin number.

Tom ROM after wiring.

All three ROMs wired.

After wiring all the ROMs I attached a 1/8 inch jack to each end.  84 jacks.  Thank you eBay and China.

Attaching the 84 jacks.

I drilled a grid of holes on a blank patch panel (another eBay purchase).  84 jacks is a tight fit, so I used a drill template to lay out the holes.  For some reason a number of holes were still off, so I had to flip a few jacks to make everything fit.

Drill template and blank panel.

After all jacks attached.  Note the through hole in the top of the case for all the wires.

The final product mounted in my rack.

And the first test run:


Stay tuned for more!  I have an Akai S01 and Kawai R50e waiting for the same treatment…


About morganhendry

I have been a musician and rocket scientist since 4th grade. I play drums/keyboards for the LA based instrumental rock band Beware of Safety (, write electronic music as The Laterite Road (, and just landed something on Mars ( More info can be found at my website ( Sign up here for updates on my many projects:
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1 Response to Circuit Bent Roland DDR-30

  1. Pingback: Circuit Bent Akai S01 Sampler | morganhendry

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