CHD MIDI Upgrade for the Roland TR-808

CHD TR-808 MIDI ModWhen writing about the MTG TurboCPU upgrade I promised to put a blog entry up for a really nice and non-intrusive MIDI mod for the Roland TR-808, and here it is. The thing I really like about this implementation is the degree to which they went to make in non-intrusive (i.e. drilling holes!).


CHD TR-808 MIDI ModIt comes complete with a printed manual of step-by-step instructions, and supporting CD.

For the MIDI connector the existing Din-Sync connector is removed, along with its In/Out switch. A new connector that includes MIDI In/Out is fitted (a special adapter cable is supplied. The switch is replaced by a 3 way one, In/MIDI/Out.

CHD TR-808 MIDI ModThe “umbilical cord” for triggers and power is socketed at the controller end, so for service it can be unplugged and the TR-808 will still work (so this is not a CPU upgrade/replacement like TurboCPU).


CHD TR-808 MIDI ModOnly one hole needs to be drilled, and it is for a MIDI active Led and sits in the Start/Stop switch, under the yellow label. Awkwardness here is that they specify a metric drill, and for accuracy a CHD TR-808 MIDI Modwoodworking one is probably best. I’m sure you could get by with a slightly larger US drill and use a band of shrink-wrap tubing or some-such to tighten the fit. Of course you could ignore this step and just know that center switch is MIDI on!

Be sure to keep the parts removed such that the TR-808 can be put back to standard if need be. Here is a link to the CHD TR-808 MIDI kit. I may well contact CHD and offer to distribute this in the USA.

2 thoughts on “CHD MIDI Upgrade for the Roland TR-808

  1. The problem occurs if the 808 is MIDI slaved and you’ve programmed in 16th note AC (or CB, CP or any any of the audio out port) triggers in one of the patches on the 808 and you start the 808 via external MIDI command, sending start AND note-on messages via MIDI. Some of the triggers in the 808 are dropped out and not transmitted from the 808 when multiple note-on messages are sent simultaneously, e.g., kick and snare on step 9 then the AC trigger is not transmitted. It’s a pretty bad bug to have. I have contacted them but have received no response for about 6 months now.

    • Tim/ folks reading this blog,

      I do not have a CHD MIDI modified TR-808 here to verify this issue, but have posted the issue here such that maybe someone that does can verify it and put a report in to CHD to help raise the level of the issue with their support.


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