Mark Washeim's Midi Billow Is a Raspberry Pi RP2040-Powered Python-Programmable Pocket Mellotron
New upgrade to the original Billow delivers MIDI control over the cassette tape's motor, in the same compact form factor.
Software developer and artist Mark Washeim has designed a pocket-sized gadget for the musician on the go, combining classic analog and modern digital technologies: the Midi Billow, a five-button Mellotron built into a portable tape deck.
"Midi Billow is a five-button, six-note Mellotron in a portable cassette player," Washeim explains of the device, which is a MIDI-capable upgrade to the earlier Billow. "Unlike [the original Billow] it has a MIDI input to control motor speed. The two modes are exclusive. The MIDI mode can ONLY be used with loop tapes. MIDI mode eats long play tapes. The MIDI control is implemented in Python to make it easy for beginners to play about. The player can also be used as a normal cassette player."
The Mellotron tape sampler launched in 1963 as a successor to the Chamberlin, offering a simpler production process that brought down the price of the gadget. An electro-mechanical instrument, the Mellotron connects keys to a cassette tape player — causing different parts of the tape to be played for each key as well as delivering control over the speed of playback. Washeim's Midi Billow, and the simpler Billow that preceded it, may lack piano-style keys, but the concept is the same — with the five buttons on its face controlling the playback of a cassette tape.
The Midi Billow can be used like the earlier Billow, but also offers speed control over a MIDI interface to its Raspberry Pi RP2040 microcontroller. "The range, given the motor, is limited," Washeim admits. "If you tune microtonal, 24 intervals, not log, so microtonal. In practice I find 13-14 usable intervals. If you try to tune it to notes, max eight notes. But default, it's set up so MIDI notes 49-63 are equal divisions and 64-74 are log 'musical' divisions. This is probably all you ever need, but, one can 'fine tune.'"
Hardware design files and source code for both the Billow and Midi Billow are available on GitHub under the reciprocal GNU General Public License 3; Washeim is selling fully-assembled Midi Billow units on Tindie at $130 each, with the original Billow priced at $88.