Swarmatron

The Swarmatron is an analogue synthesizer or electronic musical instrument that uses a ribbon controller rather than a keyboard. It is noted for its use of multiple oscillators that are linked through a 'swarm' control, giving its distinctive sound and method of playing.
Operation.
The Swarmatron is a fingerboard synthesizer like the Trautonium or Tannerin. A finger is placed or slid from side to side along a ribbon controller, controlling the pitch. Glissandi are obviously easily achieved, or careful finger placement may be used to play discrete notes.
The distinctive feature of the Swarmatron is its use of eight individual oscillators, under a single control. These oscillators produce an equidistant chord, where their spacing is under the player's immediate control. There are two ribbon controllers: the larger controls the pitch in the obvious manner, the second is used to control the spacing of the oscillators when in 'Swarm' mode. A large central knob on a rotary control may also be used to control this swarm.
The oscillators may also be switched on and off individually by a row of switches. With all but one switched off, the instrument becomes a simple ribbon-controlled monophonic synth, capable of the usual glissandi. Using combinations, and adjustment of the range control, allows a non-equidistant swarmed chord to be produced. The oscillators may also be preset to the usual chord intervals of major thirds etc.
The pitch control also controls a low-pass filter. This may either track the main pitch, or may be controlled by the second ribbon. With the sawtooth wave of the oscillators, this tracking filter controls the sound of the instrument.
As for many other analogue synths, there is also an ADSR envelope control.
Like the Persephone, the tuning controls for the ribbon's base frequency and overall range have such a wide span that the ribbon controller itself is unlabelled, although some players mark note positions on the ribbons for a piece.
There are no facilities for MIDI. However, there are three analogue 0-10V Control Voltage (CV) inputs for pitch, filter cutoff and swarm. With the use of a standard MIDI to CV converter, the instrument may be controlled from a sequencer or other MIDI controller.
Dewanatron.
The Swarmatron was developed by Dewanatron, the Dewan cousins, Brian and Leon. They are still hand-made by the Dewans, explaining their high price-tag. Previous instruments such as their Melody Gins and Dual Primate Console have also used the same principle of multiple, interacting oscillators. These instruments also show the Swarmatron's retro styling of dark wood cases with hammer-finish green paint. Knobs and switches also show a distinctly retro influence. Front panels labels are deliberately minimal, controls being labelled with single letters rather than words.
Dewanatron sell their Swarmatron through Big City Music of Los Angeles. As of March 2016, only 83 have been produced.
Notable appearances.
Trent Reznor and Atticus Ross used a Swarmatron in his soundtrack for the 2010 film "The Social Network". The DVD includes a bonus feature of Reznor discussing the instrument.
Reznor and Ross's band How to Destroy Angels and their eponymous first album are as yet the most prominent users of the instrument.
Derived instruments.
"The Swarm", a software drone synth for the Mac and Windows has been produced, inspired by Swarmatron and Trent Reznor's soundtrack. Although this emulates many features of the Swarmatron, and adds MIDI control, it does not include the hardware features of the ribbon controls.