American Innovations in Electronic Musical Instruments
Percussion Interfaces
Drum controllers, which give percussionists access to the world of electronic sound, are related to keyboards, in that they essentially measure contact and impact velocity. Early percussion interfaces were made during the late 1960’s, with simple acoustic pickups attached to surfaces that were struck; the signals from these transducers were routed through envelope followers (common items in the early modular synthesizers) that produced a voltage proportional to the strike intensity, together with a discriminated trigger pulse. These signals could then be routed to the various synthesizer modules for producing sounds. The first widely-marketed drum interface was the Moog 1130 Drum Controller. This device, introduced in 1973, employed an impact-sensing resistor in the drumhead and gave audiences their first exposure to synthesized drums in the concerts of progressive rock bands such as Emerson, Lake and Palmer. Other such controllers, most featuring minimal built-in synthesizers, followed in the pre-MIDI era of the later 1970’s and can be heard in much of the dance/disco music of that time, notably the Pearl synthetic drums, the Synares, the Syndrum, and the inexpensive electronic percussion interfaces from ElectroHarmonix.
Electronic percussion took a major leap in Great Britain during the early 80’s with the designs of Dave Simmons, which combined new appealing sounds with very playable flat, elastic drumpads in what were then exotic shapes (eventually annealing into the familiar hexagon); these devices also evolved a MIDI output for driving external synthesizers. The Simmons SDX drumpads introduced the concept of “zoning”, where hits of varying intensity in different areas of a single pad could trigger different sonic and MIDI events.
Nowadays, although Simmons are long-vanished, nearly every musical instrument manufacturer makes electronic percussion interfaces. One of the longest lines of innovative percussion controllers arise from US manufacturer KAT, who make products such as electronic mallet interfaces for marimba players. Most percussion devices use Force-Sensitive Resistors (FSR’s) as sensing elements, while some incorporate piezoelectric pickups. Essentially all percussion pads are acoustically damped, and radiate little direct sound. In recent years, several MIDI drum synthesizer modules (e.g., the Alesis DM series) incorporate analog inputs for 3’rd party percussion transducers, enabling triggers from essentially any source to produce MIDI output. By necessity, these devices are very adaptive to signals of different character; all relevant parameters (such as trigger thresholds, noise discrimination, crosstalk between pads, etc.) can be digitally adjusted and compensated through menu parameters for each transducer channel.
In recent years, the famous synthesizer innovator Donald Buchla has been directing his attention to designing new musical interfaces. One of his devices, called “Thunder”, can be thought of as a very articulate percussion controller, designed to be played with bare hands. The flat surface of Thunder is split into several labeled zones of different shapes, adjusted to complement the ergonomics of the human hand. These zones respond separately to strike velocity, strike location, and pressure. Whereas the original Thunder designs employed capacitive touch sensing, later renditions use electro-optic detection of the surface membrane’s deformation under hand contact.
At the MIT Media Lab, we have built perhaps the world’s largest percussion interface in the “Rhythm Tree”, an array of over 300 smart drumpads constructed for the Brain Opera, a big, touring, multimedia installation that explores new ways in which people can interact with musical and graphical environments. Each pad in the Rhythm Tree features an 8-bit microprocessor that analyzes the signal from a piezoelectric foil pickup and drives a large LED, both potted in a translucent urethane mold. A MIDI stream is then produced, which triggers sounds and gives visual feedback by flashing the LED in the struck pad or illuminating others in the vicinity. All parameters (thresholds, modes, LED intensity) in each pad are completely and dynamically downloadable from the host computer.
The “Drum Machine” although not strictly a controller, is an important part of electronic percussion’s history. Early units stored drum patterns in digital memory and generated all sounds from analog sound sources and filters. Roger Linn revolutionized this in 1980 with the LM-1 Drum Computer, made by his company Linn Electronics in Hollywood. The LM-1 used digitally sampled drum sounds instead of the simple analog transients played by its predecessors. The LM-1 and its descendants (such as the E-Mu Drumulator) opened up the entire world of percussion to drum sequencers. Today, this capability has been absorbed into standard synthesis gear; nearly every synthesizer has a large set of percussion sounds stored in its wavetable.
From American Innovations in Electronic Musical Instruments
by Joseph A. Paradiso
© 1999 NewMusicBox