Boss DR55 Users and Modders? Looking for info on this machin

ericcoleridge · Joined: Jan 16, 2007 Posts: 883 Location: NYC

I've always liked this simple programmable rhythm box. I had one once and got rid of it because it played kind of quirky and it didn't seem worth the trouble at the the time.

BUt, I'd like to try one again. Only the prices are plum stupid for these now. They sell for nearly as much as a 606 for some reason. They were always $50-$75, forever. Then all of a sudden $350.

But, after looking over the service manual-- I don't see anything special here besides a 10240Bit CMOS RAM IC, TC5501.

Does anyone know-- is there anything here that needs to be set up or programmed-- or could someone just put these parts together and expect this thing to start up and start jamming?

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v-un-v · Posted: Sun Mar 25, 2012 8:23 am Post subject:

I've just sold mine. But before it went I toyed with the idea of swapping out the tone control and replacing it with a decay control for the bass drum.

In the usual Tom fashion I never got round to doing the mod. Confused

infindebula · Joined: Sep 29, 2011 Posts: 26 Location: Canada

There is no firmware. The machine has no processor.

The CD4011 is a bit fussy ... a few years ago I repaired one of these machines with a bad 4011, and the replacement I used caused pattern writing to work incorrectly. A different 4011 fixed the problem. I'd probably try to stick to the original RAM IC too.

You might have a bit of trouble getting the exact same transistors specified, particularly the 2SA733P (the same high-gain that people try to snatch up for their x0xb0xes).

It never occurred to me to just copy the whole circuit and make your own, but it should actually be pretty straightforward.

I think the sequencer on this drum machine is pretty crappy by today's standards, but it might be worthwhile just to do the sounds. Remember, it doesn't even allow you to program hihat parts! Also, by using an external sequencer you can put a long or short gate on the snare sound (listen to the offbeat snares on the opening of "Computer World" by Kraftwerk - it is most definitely a DR-55)

v-un-v · Posted: Mon Mar 26, 2012 1:41 pm Post subject:

The sequencer is a MAJOR PITA to program!!! The main reason why I sold it. However, the actual box when running is funky as hell! Think Led Zep does Electro! Cool

ericcoleridge · Joined: Jan 16, 2007 Posts: 883 Location: NYC

elektro80 · Posted: Wed Mar 28, 2012 2:56 pm Post subject:

I have one of those here somewhere still. It is easy to program and it sounds pretty bad. I bought it new in early 81 I think..

The one unique thing here are the DBS and CSQ outputs. See attached image.. scanned from the manual.

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elektro80 · Posted: Thu Mar 29, 2012 7:26 am Post subject:

The DR-55 can be the clock for external gear and the programmable accent can be used for stepping/triggering whatever.

befacosynth · Joined: Jul 20, 2010 Posts: 21 Location: Barcelona

infindebula · Joined: Sep 29, 2011 Posts: 26 Location: Canada

that's really good info, befacosynth. thanks!