Roland Trigger out for the MB-808

As an add-on to my MB-808 I have built this small circuit to trigger the internal sequencer of a SH-101 as well as the the arpeggiator of a Juno-60. The original trigger signal of the Roland TR-808/606 and some other Roland instruments has a square waveform with a duration of 1ms, and a minimum of +2,5V, while the trigger signal from the MB-808 circuit is way shorter; With the friendly help of some people at the german synthesizerform I built this small circuit, grabbed the two trigger signals from the shift registers of the Midibox Sequencer, activated these two external triggers in the Midibox firmware and led the two trigger signals to external jacks on the back. Quite easy, and a lot of fun!


2 x 2N3904
R1 = 47k
R2 = 10k
R3 = 47k
R4 = 4k7
R5 = 10k

Finally complete: MB-808 the Bassqueen!

teaser picture MB-808

Yes, thats right: 10 months after starting to build this baby, she´s finally ready and sounds great! The MB-808 is a clone of the famous Roland TR-808 with a Midibox step sequencer; The bassdrum has this loooong boom, the snare comes snappy and sharp, the toms go pretty deep while the congas almost self oscillate, clap and rims sound just as warm as the original and the hihats groove nice! She has swing, accent, 2 additional trigger for the classic SH-101 & 808 combination or the arpeggiator of some other synth; the digital heart of the MB-808 is the Midibox sequencer, with a rock-solid timing and quite a bunch of useful features; check out the MB-808 project here as well as the Midibox home for more information.

I started this project last winter, when someone on the german synthesizerforum offered me one of the few PCBs of the second batch of the MB-808 project. After sourcing and ordering all the parts I started soldering in january, and soon had a basic running machine at the end of february – but it took me quite a while to source and fix some errors in the analog circuits of the toms and hihats, complete the case (I tried out several options, the final case has been laser-cut and powder-coated by one of my relatives in his factory), order the knobs, draw the artwork for the case and get it silkscreened at a printer here around…

So here´s the first sound sample, more stuff will follow soon;
MB808 soundsample by markburow




Thanx to Doug Wellington and Jeff “Moogah”, who started this project and did the great PCB layout and the documentation, and Torsten Klose, the father of the Midibox project. Great work guys!