LEGO MIDI Percussion Toolkit

Serching for “MIDI” + “percussion” + “LEGO” is training my search engine cookies. A few weeks ago I found this video of “Dada Machines” kickstarter campaign:

Such a great idea! I already knew about commercial MIDI adapter for playing just one drum and several “makers” or DIY projects using Arduinos and servo motors but Dada Machines idea of selling pre-made “modules” make things much more “clean” and interesting – each module can work as a solenoid or a mallet and can even be adapted to fit LEGO elements with studs so it really looks “plug and play”.

Now let’s think more about it:

  • a MIDI controller with several outputs is something I already been doing, a Technic Hub has 4 ports, looks like a nice start… and it can scale out quite well as I already found out with the LEGO Bagpiper
  • there are so many ways of mounting LEGO Technic… a few “actuator modules” look very feasible
  • and some of those percussion instruments on the video look really possible to achieve with LEGO parts (yes, that table with marbles, I am looking at you!)

But I was on holidays and had not enough Technic parts with me for a proof of concept (“I knew I should have brought more LEGO!”) so had to wait until back home.

I decided to use a BOOST motor for a solenoid-like module and copied Yoshihito Isogawa ‘Reciprocating Mechanism #63’ from his excellent “The LEGO MINDSTORMS EV3 Idea Book”. And since I had 2 of this motors available and a also a City Hub…

Then I found myself picking up all kind of objects at home to see how they sound when “banged” with those solenoids (“boy, this is addictive!”). I went to my #2 kid and took back those IKEA BYGGLEK boxes he was no longer using… nice sound, but for a drum-like sound a mallet actuator is better… and a stronger and faster motor is also better… so the second version of the Percussion Toolkit needed a more powerful hub for all those power bangs… and also found enough GBC balls to make that percussion table from Dada Machines:

Then I focused a little more on the software side. I was already parsing a MIDI stream and playing each percussion instrument according to the MIDI event I wanted (like “Note on 9 35” i.e. “Acoustic Drum” because on the MIDI Percussion Channel each note is mapped to a specific instrument) but without the remaining instruments most musics I played sounded very strange. So I wanted to split the MIDI stream in two – the percussion instruments would be parsed by the current setup and the remaining instruments would be forwarded to a Synth so I could listen them in a speaker.

Turns out this is very easy to achieve in linux with ‘qmidiroute’.

So after some minor adjustments and the addition of a fourth instrument, I now have a 4-instrument 100% LEGO MIDI Percussion Toolkit:

And all the micropython and python and bash scripts are available:

As soon as I get more hubs will try to scale it out (the U2’s Sunday Bloody Sunday song uses 5 percussion instruments and I now have this crazy idea that a basic bass would sound great with Queen’s Another One Bites the Dust).

Then I will try to settle down on a few modules standard so this can be adapted easily to other instruments.

Then… I know… the software needs some attention.

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