MATRIXSYNTH-B: 05/05/12

via this auction

"First, this is a drum "brain" --- that is, there is no on-board sequencer/rhythm maker----you need to trigger it with a sequencer or something else. Originally, this was used back in the 80's I guess, triggered by electric drum pads. Now a days, people trigger it with other drum machines, sequencers, or their computers via a MIDI-enabled mediary (e.g., Roland TR-808, 909, 707, etc). Second: this is triggered with analog-ins. You need a triggering-source with enough amp/voltage in that triggering-source (something I never fully understood, I'm not an electrician) to get a good signal out of the DRUM-X. Generally its been my experience that analog-keyboards have no problem triggering it. I personally use a Roland TR-707 to trigger it (which works beautifully), and its my understanding the Roland TR-727, TR-808, and TR-909 also trigger it with no problems based on what I've seen on the internet---however, not all Roland TR drum machines trigger this (that is, other models besides the ones mentioned above) so beware. The beauty of using a Roland TR-707 (or 808, 909, 727, or anything else that works) is that the Roland machine is MIDI-compatiable---so in other words, I have been using a software sequencer (Cubase) to trigger via MIDI my Roland TR-707, which in turn triggered my Pearl Drum-X and SC-40 via its analog-outputs..."