Wednesday, January 12, 2011

The Ring Modulator

For well over a century, music composers have allied themselves with engineers. For an example, consider German engineer Harald Bode, whose groundbreaking work in electronic sound modification was inspired, in whole or part, by the innovations of songwriter and guitarist Les Paul. Bode observed:

Les Paul . . . stimulated many innovators, and due to his success encouraged them to work in the field of new sound effects. His influence in many areas is felt to this day. The author [Bode himself] was so impressed by his work that he later developed a sound modification system consisting of a number of electronic modules, assigned to two separate outputs through a multiple-head tape loop device. These modules also included a ring modulator.

Note that Bode indicates he was interested in the development of sound modification by means of a device with several modules, research which would later influence both Robert Moog and Don Buchla in their development of the modular synthesizer. Bode did not invent the ring modulator, however, which was a device developed for applications in single-sideband (SSB) modulation. (SSB modulation was used early on with long distance telephone lines as part of a technique known as “frequency-division multiplexing” which allowed several voice channels to be sent along a single circuit.) Back then, though, in the early 1930s when long distance telephone service was being developed, it wasn't known as a ring modulator:

The ring modulator was at the time [ca. 1959-60] relatively little known sound modification device, mainly used in single-sideband communication systems. The main reason was that up to the mid- or late 1950s it was known as a switching circuit, which would have sounded too harsh to be usable for sound modification. It was only after ring modulators were built with diodes, which operate in the square law region of their transfer function (as was the case with certain germanium diodes), that they started to perform as four-quadrant multipliers and became musically interesting.

In technical terms, a ring modulator (named as such because the electronic circuit is shaped like a ring) is an analog sound modification system that takes two inputs, one a signal and the other a carrier frequency, and produces a single output. The signal is normally a wave form produced by the output from a microphone (e.g., a voice), while the carrier signal is normally a sine wave. The function of the ring modulator is to produce the sum and difference frequencies of the signal and carrier. In layman's terms, a ring modulator produces a spectrum of noise, or what Karlheinz Stockhausen, here, refers to as “colored noise.”

It was probably electronic music pioneer Karlheinz Stockhausen’s use of the ring modulator that inspired an entire generation of rock musicians. Stockhausen’s Mixture (1964), for example, was written for a ring modulated symphony orchestra. In this electronic composition, the orchestra is divided into five groups (wind, brass, two groups of strings, percussion) and individually mic’ed, each group fed to a separate ring modulator. Stockhausen’s next work using the ring modulator was Mikrophonie II (1965; 14:52), composed “for choir, Hammond organ and ring modulators.” In the liner notes to the Columbia Masterworks LP containing Mikrophonie I and Mikrophonie II (MS7355), the composer wrote:

Mikrophonie II offered the possibilities, as does purely electronic music, to compose with a scale of sounds ranging from natural to synthetic, from familiar (nameable) to unfamiliar (unnamable) ones. The ‘what’ (the material) is not separable from the ‘how’ (the forming). I would never have composed as I did, had the ‘what’ of this process not had very specific characteristics which lead to a specific ‘how.’ For example, when one uses ring modulation, one must compose particular kinds of structures - simple superimpositions, many tones of long duration, not-too-rapidly moving layers - since ring modulators create dense symmetrical spectra from simple material, and this can easily lead to an overweight of noise or a stereotyped coloring of the sounds. . . . the transformation of the choral sound in Mikrophonie II has many gradations, that often untransformed layers are found mixed with more or less transformed layer, and that there is a transition from natural to synthetic sound, and vice versa.

Hence, for Stockhausen, live performance was a form of engineering, a process by which sounds were made, not “captured.” Although the ring modulator is often associated with the synthetic voice of the Daleks in the long-running Dr. Who television series (in which the ring modulator, in other words, is used to simulate the synthesized voice of the robot, the simulation of a simulation) there have been some memorable uses of the device by rock musicians following Stockhausen’s rule regarding the inseparability of the what from the how.

Sonic Samples Of The Ring Modulator:
Jeff Beck - With The Jan Hammer Group Live (1977)
Billy Cobham - “Snoopy's Search/Red Baron” Spectrum (1973)
Jerry Garcia (The Grateful Dead) - “That’s It For the Other One” Anthem of the Sun (1968)
Jan Hammer (The Mahavishnu Orchestra) - “Vital Transformation” The Inner Mounting Flame (1971)
Tony Iommi (Black Sabbath) - “Paranoid” Paranoid (1970)
Jon Lord (Deep Purple) - Machine Head (1972)
Gordon Marron (The United States of America) - “The Garden of Earthly Delights” The United States of America (1968)
Bob Mothersbaugh (Devo) - “Too Much Paranoias” Q: Are We Not Men? A: We Are Devo! (1978)
Bob Mothersbaugh (Devo) - “Mechanical Man (Booji Boy Version)” Mechanical Man EP (1978)
Ozzy Osbourne (Black Sabbath) - “Planet Caravan” Paranoid (1970)

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