Lego drummer

Many e-drummers are also Lego fans, so here’s an experience that ties the two hobbies together.

Lego enthusiast Brick Technology (he prefers to keep his identity secret) recently posted a YouTube video showing how he built a Lego drum machine to power a Roland TD-9.

The video shows the build step by step and culminates in a demo of the machine in action, together with a guess-the-song quiz at the end.

We asked the mind behind the machine about the build.

dD: Why did you start the project?

BT: I run a channel and try to come up with interesting ideas that no-one has tried before. I knew Lego Technic is capable of a lot of things and

wondered if it could be used as a sequencer to trigger MIDI instruments.

Since I was limited to using pins, I knew I needed an instrument that works on short impulses. Pianos and any instruments where a note has a specific length were out of question. The xylophone seemed to be boring, so I decided to go for electronic drums, because they are triggered by simple and cheap electric components called piezos.

dD: How did you set about designing it?

BT: The entire device is designed around the hammers/levers that hit the piezo.

The design required specific dimensions and positions to move quickly in order to play fast drum beats.

I decided to use a Roland TD-9 sound module because of the 10 trigger inputs and the possibility to split inputs into two triggers. This sound module also allowed me to adjust trigger parameters such as crosstalk and threshold, which is very important for this machine, as all piezos are mounted very close to each other.

The roller was transformed into a belt that is 16×8 bricks long to program a typical 4/4 drum loop.

I used Superior Drummer 3 as the sound source as it was much easier to replicate a known song’s drum sound with software.

dD: How long did it take?

BT: The design itself took around six to eight hours, while preparation (ordering components) and making my video took much longer. I usually need around two or three weeks for a video including research, preparation, designing, testing, filming, editing and uploading.

dD: What interesting discoveries did you make along the way?

BT:  That the Taylor Swift Shake It Off drum beat has been harder to program than System of a Down’s Chop Suey. In general, programming the beats took a lot of time: I used MIDI notes, drum tutorials and drum-only tracks to recreate the beat.

Also, the trigger settings of the TD-9 had to be heavily modified to avoid cross triggering.

The system has its limits, too. There is no hi-hat opening and closing other than using different MIDI notes for open or closed sounds. There is no velocity change, and fills in strange timings (6/8) cannot be programmed. It was also very difficult to find the right RPM of the Lego motors to correspond to the desired BPM. I am sure I could have come up with a formula and calculated it, but in this case, I just did this by ear.

To view the video of the build and see the Lego Drummer in action, click here.

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