Larry Cotton’s MIDI Robot Marimba: Update

Over 4 years since Larry Cotton’s “player marimba” was featured in Make and subsequently retrofitted for MIDI using MD24 MIDI decoders, the instrument is still going strong. Larry recently updated the drive circuitry, replacing the original relays with NPN Darlington transistors to drive the mallet solenoids. Video of the marimba in action can be found here and here.

MIDIMarimbaLarry writes:

My MIDI Marimba (which uses 2 of your MD-24’s) is 90% refurbed.

The MD24’s work perfectly, and are more than capable of triggering the TIP-120’s, a vast improvement over relays, etc.

I also added RCA plugs and jacks to the mallets, for easy servicing and assembly/disassembly.

The first pic shows early stages of the new wiring. The power supply’s pretty beefy for the solenoids, with adjustable output around 12V, and 5V for the MD24’s.

The second pic was taken just before all the wires were stuffed in and the plexiglass cover installed.

The third pic shows it all buttoned up. That’s an iRig Keys keyboard on the floor, and an ancient Gateway laptop running Cakewalk software. I’m also using an M-Audio Uno to deliver MIDI to the MD24’s.

The wonderful little iRig Keys allows the marimba to be recorded and played manually. Kids love it.



MIDIMarimbaSystemThe picture below shows an initial test of the MD24 and TIP120 driving one of the marimba’s solenoids. Video here.




Highly Liquid user profile: Pastel Fractal

Chicago-based artist Alexander DeGraaf employs several UMR2 and MSA-T boards for his ongoing project Pastel Fractal. Alex uses MIDI control for robotics and live audience participation in addition to more traditional sequencing and synthesis functions.


Alex writes:

I have three sampling keyboards into which I have installed UMRs: two Yamaha VSS-30s and one Casio SK-8.  I use different samples on the keyboards for different compositions such as: my singing voice, a dog bark (sampled from SK-5), a TR-808 clap, a Doc Watson banjo riff, a Chet Atkins guitar riff, and some scatting sounds.

In my installation sculptures, I’ve used as many as two MSA-T MIDI Decoders to turn my MIDI note messages into voltage pulses for as many as fourteen small 24V solenoid motors. I’ve engineered these motors to reset immediately after being triggered, and I’ve connected them in various ways to percussive elements within the sculptures. In this way, I am able to MIDI-sequence robotic percussion strikes and sounds in sync with my compositions that are otherwise played by more conventional MIDI sound engines such as synthesizers, keyboards, and drum machines. The robotic percussive elements within the sculpture each provide a unique source from which sounds stimulate the inhabitant of the sculpture. I provide additional sound sources – besides robotic percussions and the main P.A. – by attaching small speakers to individual keyboards and drum machines so they may be hung around the sculpture or handed out to the inhabitants to pass and move about. Thus, inhabitants of the sculpture – also known as members of the audience – can contribute to the composition during a performance with these floating pieces of hardware by engaging buttons or keys within their reach.

More from Pastel Fractal can be found at Vimeo, Soundcloud, and Facebook.

Disappearing Cowboy’s Automated M.O.T. Stage Rig

John Erik King, the sole instrumentalist of Disappearing Cowboy, has created the “Minimalist Organic Tech” stage rig, an integrated system that includes guitar effects and amplification, bass, synthesis, vocal processing, and robot drums. Scripted MIDI messaging provides “scene” control, freeing King to simultaneously perform live guitar, bass, and synth.

M.O.T. Minimalist Organic Tech from Disappearing Cowboy on Vimeo.

King’s description of the system:

  • kick, one actuator.
  • snare, one actuator.
  • ride cymbal, two actuators to account for the high volume of repetitive patterns typically played on cymbals.
  • toms, two actuators, again to account for quarter/sixteenth note repetition.
  • crash, one actuator with a very long throw to really smack the crash cymbal so it stands out.
 M.O.T. Rig
  • bass, mute, and distortion control. (big muff)
  • guitar, Moog LP ladder filter into an eventide stereo digital delay. The stereo output then goes to two different amps with independent mutes.
  • synth, only one string goes to a Roland GR-30, which has its own mute as well.
M.O.T. Batar
  • has three outputs. Bass, guitar, and synth.
  • tuning E (bass string), E,B,E,B,E. (five other strings)
  • top three strings are attached to a modified Bigsby tremolo which creates a relative detune effect.
Because everything is controlled by MIDI, we can shift scenes and tempos for each song, or even in between songs. The vocal delays and guitar delays are in perfect sync with the tempo which the drums precisely adhere to. If the tempo is at 135, everything is locked at 135.
I originally controlled everything with a laptop, but found a karaoke device that plays back MIDI files to use instead.
All the different scenes and transitions are triggered automatically. And the entire set is set up like a playlist. We hit one button and the entire show plays without any foot controllers or input like that of any kind. It’s all automated, with the exception of playing the instrument, of course.


The rig employs two Highly Liquid MSA-P MIDI decoders to trigger drums, route audio signals, switch amplification channels and control effects.  An MPA MIDI decoder is used to automate control of the Moog ladder filter.

The new Disappearing Cowboy album, Revolute, is available from every major online music distribution platform including Amazon, iTunes, Soundcloud, and several others.


Tim Laursen’s Robot Drum Creation

Tim Laursen combined a power supply, drum machine, mixer, MSA-R MIDI decoder, Darlington drivers, and a collection of individually miked, solenoid-actuated drums.  The result is “Double Rainbow”, a complete mobile robot drum system.

Some technical details can be found in this forum thread.  Tim’s work also appears in this video from Sequence of Waves.

2010 Maker Faire Detroit

Several “makers” at the recent Maker Faire Detroit demonstrated projects that incorporate Highly Liquid MIDI decoders.  For more photos, see the new Highly Liquid Photostream at Flickr.

Chip Flynn (Apetechnology) brought several robots, including an MSA-R controlled string instrument (background left):

Dana Dolfi demonstrated the MSA-T controlled Great American Horn Machine:

Dave Kadlitz performed with his MSA-R & MSA-T controlled mechanical drum machine, the “Waits-o-Matic 9000″:

Michael Una performed with an MD24-synced DIY sequencer:

Robot Drummer: “Spruce Deuce”

Steve Averill‘s robot drummer first appeared in this blog as a pair of disembodied plywood forearms.

The “Spruce Deuce” has since become a sophisticated android drummer brought to life by 11 RC servos.  Servo control signals are generated by a single MD24 MIDI Decoder:

Compare to Steve3PO, an MSA-T driven MIDI robot drummer.

Other MD24-based MIDI percussion projects are underway and are being discussed at the Highly Liquid Forums.  Have you joined the forums yet?

User Project Roundup, Part 9

Steve, a robot drummer based on the MSA-T MIDI decoder, built by Texas Central Positronics.

Video here, here, and here:

Komega‘s MD24-based Musifore MIDI visualizer:

MIDISpeak / Speak & Spell controlled by Ableton Live.  Video here and here:

A Yamaha CS01 with an installed CS01-MIDI kit, controlled by an x0xb0x:

The latest suitcase SK-1 from The Umbrella Company, with installed UMR for MIDI control:

User Project Roundup, Part 7

Forum member GoatBoy used the MSA-R to provide MIDI control for an array of solenoid-activated bells.  (Note: The MSA-T and MSA-P may be better choices for solenoid-based projects.)

Spunky Toofers used an Akai EWI 3000 to trigger a MIDISpeak and effects.

Siempre La Luna documented the MIDISpeak assembly process and installation process.

Thomas S. photographed his MIDI Xbox controller for use with music games.

User Project Roundup, Part 5

Steve Averill’s robot drummer, using the MD24 for MIDI servo control:

Atari 2600 + MIDI2600 + Synthcart + Ableton Live + Modular Synth demo (SYNCHRO):

Bob Lloyd‘s animatronic Halloween program, which uses MSA-T MIDI decoders for MIDI lighting control:

A MIDI retrofit of the Synare Percussion Synth using the MSA-P (the simulacre):

A vintage Ace Tone Rhythm Ace drum machine, MIDI retrofitted by Kerry Bradley using a MIDI2600 kit (Note: the new MD24 is a better choice for this type of project):