MR 808 Technique
The MR-808 interactive is a robot installation featuring the oversized robotic drum machine – programmed live by the audience. The audience can program the drum robot in a collaborative process and listen to and see the emerging of the sound. At the exhibition site, the audience can stand in front of the robot, accessing the music structures via interfaces.
The installation was developed, used and constantly redesigned over a period of 4 years and involves divers hard- and software techniques, including acoustic experiments, electronic design to the web-based collaborative sequencer running on a Raspberry2. Below you can find separate articles for different subjects. But we’ll start with an overview.
History of the 808
Base of this installation is the famous electronic drum sequencer TR-808. The original 808 was released in 1981 by Japanese brand Roland and was meant to be a replacement for a real “human” drummer for practicing and rehearsal purposes. Being the first affordable drum computer which could be programmed, the rhym machine quickly became an underground hit amongst experimental musicians. Musician like Afrika Bambaataa or Marvin Gaye started to use it in a non-intended way (hacker-style!). The 808 is said to have had a huge influence on the creation of genres like electro, techno and hiphop.
Since 2005 I (Moritz Simon Geist) am constructing musical robots and automated instruments.
The goal was and still is to build custom made instruments, which can be used in the context of electronic music.
The greater idea is to transfer electronically produced and thus fully determined sounds into the physical world, to play with robots (yay!) and to unbox technology and make it approachable for a bigger audience. And what could be better than robots and techno?
In 2013 I found Sonic Robots a loose group of friends, hackers, technicians and artists and we had the idea of reversing the concept of the 808 and putting the physical aspect back into this gorgeous drum machine
For the Installation MR-808 we began to replaced eleven sound with mechanical actuators like motors and solenoids, so that reals drums (Snare, BD ..) could be played live.
Acoustics & Mechanics
We did a lot of experiments (probably the first six month) to approach the sound of the infamous TR-808 sound. For most of the eleven instruments we carried out 3-4 experimental hock-up variants to see which sound in the reality. In the end we used ready-made instruments like the snare, the cymbals of the HiHat, but also build some instruments from scratch like the bass drum (a short bass-string from an E-guitar), the clap (wooden castagnet like blocks made from old piano mechanics) or the clave (two wooden hands holding a wood block). A detailed article describing this process for the clap instrument can be found here.
When starting dealing with robots and music in 2005, I started with the Midibox project which was based on PIC micro controllers. Arduino wasn’t invented yet and Midibox was the go-to plattform already featuring modules (Analog and Digital IO, Controls, PWM). But it was hard to develop (flashing software with the RS-232 serial port, yeah!) and inflexible to handle. With the rise of arduino things got easier and now everybody can plug together some shields and be cool and hacky for 20$.
And thats what we did!
- Midi-In: A simple midi-in circuit and a midi splitter handles the Midi data and protects the micro controllers with an optocoppler.
- Micro Controller: An Arduino Mega translates the midi notes from one channel to one of the 54 available digital I/O Pins of the Mega board. The actual power unit consist of an array of Mosfet, which are capable of switching up to 50A per channel at 12V. We use XLR connectors to connect the instruments with the power unit.
- Light: in the cabins of the MR-808 white high power LED stripes are installed. These are controlled with an ATMEGA, receiving midi data. An TLC5490 chip (PWM controller) generates fade-out effects for the channels. Have a look at our article here.
- Power supply We choose to use switching power supplies from computer servers as the energy supply. This has the advantage that one can have a lot of power output (usually 50A / 12V) at a very compact format (2Kg) and they are cheap (20€ at ebay).
The big disadvantage is that switching power supplies doesn’t provide galvanic isolation which can be a life-taking risk in a faulty situation.
In the structogram below you can see the main parts electrical and IT parts of the MR808.
Software for the electronic
NOTE: We wrote a detailed article about the interactive software and electronics here.
The robot speaks Midi. But its not as easy as connecting an electronic drum machine: When talking about robots and music one has to talk about latencies, too.
Every robotic music instrument has a latency, which is the sum of all delays (mechanic ways from the actuators, MIDI-signal, electronics conversation). If we trigger a MIDI note on a keyboard the tone can be heard with this latency delayed. As this can be up to several 100 microseconds, this is bad for live playing and accuracy. In my point of view this is one of the biggest issued when building robust music robotic instruments
There are several ways to deal with this issue. One is to build robots with (mechanically) short ways from the actuator to the acoustic element. This has the disadvantage of being less aestsetical and impressive (big and long movements = good!).
Another solution is to fix the latency in software: to delay every instrument appropriately. This is a little complex topic so be sure to check out the dedicated article here.
When building the MR-808 installation we needed roughly 18 month for building the instrument and the electronics. The last thing we build was the 3.3m by 1.7m big wooden housing. The plan was to build it in one piece, of wood or even metal. When starting with the design (in sketchup!) it was clear quite quickly that we had to build several parts. In the end we build five parts, which can be disassembled for transport. Various distinctive design elements of the original drum machine like the 16 buttons and the knobs were realized as well. We made most of the elements from thermoformed polysterol, a great and easy process. Be sure to check out or article about that here.
Be sure to check out our other article about IT and interactivity.
Because the whole building process was very complex and long we put some topics in detailed articles. You can find them here: