American Innovations in Electronic Musical Instruments

Effects and Processing

The only way to modify the sound of a purely acoustic instrument is to alter its design characteristics with mechanical resonators and other physical modifications, some of which can be nonlinear and inharmonic (e.g. John Cage’s prepared piano). While some of today’s avant-garde artists continue breaking ground with such techniques, once a transducer or pickup is added to an instrument, nearly limitless possibilities are opened for its sound to be electronically modified. Since the early days of studio recording and guitar performance, audio effects have expanded the sonic boundaries of live and recorded music. With today’s digital effects, a musician or producer has access to an endless spectrum of sound alteration capability.

As the electric guitar, the Hammond Organ, and the microphone were the first common audio sources, most original effects were designed for them. The first such modifier to be applied was tremolo, initially developed for the organ world in the late 1940’s, and moving rapidly to guitars. The tremolo unit developed by DeArmond, using a motor to rotate a mercury switch, was probably the first outboard effect. Later units used photoelectric switches, which then developed into vacuum tube audio gates, and eventually moved to transistors and integrated circuits in the 1960’s. Although the concepts of amplitude-varying tremolo and pitch-shifting vibrato were often confused early-on, the first real vibrato effect was Gibson’s GA-VI unit in 1956, followed by Magnatone’s devices released in the early ’60’s.

Reverb and echo were developed early in the history of recording. The guitar pioneers of the 40’s and 50’s (Les Paul, Chet Atkins, and others), used tape-based delay in studios for echo effects, where playback occurs a finite time after recording. Tape echo became established as a portable, performance effect with products like the EchoSonic amplifier, developed in Illinois by Ray Butts. These grew out of devices that he built for himself with wire recorders and migrated eventually to acetate tape loops in his commercial units of the mid-50’s. Stand-alone echo boxes then appeared, first the EccoFonic and more famously, the Echoplex, originally from Market Electronics in Cleveland. Despite their bulk and fragility, tape systems and their relatives (electrostatic and magnetic drums) reigned supreme for echo effects until the advent of bucket-brigade and CCD solid-state delay lines in the mid 1970’s, which were first incorporated into effects boxes like the Electro-Harmonix Memory Man and the MXR Analog Delay. Although tape systems (generally with 2 machines; one for record and another for play) were still used for long performance delays (such as in Terry Riley’s “Time Lag Accumulator” and the “Frippertronics” system by Brian Eno and Robert Fripp), they rapidly descended to vintage status. In the 1980’s and 90’s, the low cost and high density of digital semiconductor memory resulted in the demise of noise-prone analog delay in general, rendering most delay effects digital in nature.

Because reverberation requires shorter delay lines and multiple taps, difficult to attain in tape systems, recording engineers would achieve this effect by installing microphones and speakers in empty rooms, piping in and monitoring external audio feeds. Smaller mechanical systems followed, where a plate or spring would be excited by an audio signal, and the reverberated output tapped by a pickup. The initial spring reverbs were built into Hammond organs, making their way into guitar amplifiers and effects via the Fender 6G-15 Reverberation Unit in 1961. Although some reverb-like effects could be obtained from analog delay, the reverberation business became all electronic once high-quality digital units were introduced, such as the family of Lexicon devices in the 1980’s. Reverberation algorithms are now available as software algorithms, many of which can run on a general-purpose computer in real time.

Another effect that required a short delay was flanging, the familiar “whooshing” effect that occurs when two audio sources are subtracted after one has been piped through an adjustable delay. Although this became a popular sound in the psychedelic music of the late 60’s (according to George Martin, John Lennon coined the term), its roots go back much further, at least to Les Paul, who used the effect in recordings dating to 1945. While Paul’s technique used two variable-speed audio disk recorders, subsequent flangers remained non-realtime effects, generally done with two tape recorders or turntables. This likewise changed with the advent of the analog delay lines in the mid-70’s,which led to flangers by ADA, MXR, Electro-Harmonix, and Tychobrahe. In the early 70’s, however, before analog delays were commonly available, a related effect, termed “phase shifting”, became widespread. This was produced by a sweeping notch or comb filter, easily realized in the solid-state analog circuitry of the time. The first of many commercial devices was the Maestro PS-1, designed by Tom Oberheim before starting his well-known synthesizer company. Although another related effect, “chorusing”, was first attained for electronic organs by exploiting a cyclic Doppler shift with the famous rotating speaker system invented by Don Leslie in 1940, analog delay lines made chorusing standard faire for guitarists, starting in 1976 with Roland’s CE-1. As all of these effects are very simple to realize with a digital delay line, they were quickly subsumed by the digital multi-effects units that began appearing in the late 1980’s.

Perhaps the most famous of guitar effects is the fuzzbox, a nonlinear waveshaper that clips or otherwise distorts the guitar’s signal. Although fuzz was critical to 60’s rock, its genesis dates back to the 1950’s, when some musicians (such as Chet Atkins, Roy Buchanan, and others) occasionally employed distortion from overdriven inputs, malfunctioning amplifiers, or damaged amplifiers or speakers in their recordings. Nashville recording engineer Glen Snotty embodied this in a transistorized device, selling the design to Maestro, which produced the first commercial product of its kind, the 1963 Fuzz-Tone. There was no return after the Rolling Stones used one of these in their 1965 recording of “Satisfaction”, and myriad fuzz devices followed, all with their unique flavor of distortion.

Another signature guitar effect is the “wah-wah” pedal, a sweeping active bandpass filter developed by Brad Plunkett of Thomas Organ in 1966, introduced as the “Clyde McCoy Wah-Wah pedal” then renamed Vox CryBaby around 1968. A host of clones and variants of the wah-wah were produced by many manufacturers thereafter. Although these devices were mainly used to embellish guitar performances, the fuzzbox and wah pedals produced entirely new sounds with other instruments. Mike Ratledge’s fuzzed and wah’ed organ in the late-60’s Soft Machine recordings essentially defined the legendary “Canterbury” sound.

The advent of the modular synthesizer in the late 60’s both enabled and popularized a host of other effects, such as ring modulators and envelope shaping. Several of these modular patches were embodied into stand-alone effects units, such as Tom Oberheim’s 1970 Maestro Ring Modulator and the 1972 Musitronics Mu-Tron III (a semi-automatic wah effect, with filter cutoff affected by the signal amplitude).

Although real-time frequency shifting has a long history in electronic music, the devices made prior to solid-state delay lines were all linear, additive designs derived from radio technology. The most famous of these was Harald Bode’s frequency shifter, licensed to Moog Music in 1963 (Frank Zappa was one of its main popular users, for instance in the 1972 album Wakka/Jawaka). Such additive pitch shifters, however, destroy harmony, as the ratios between partials are not conserved when the pitch is altered. After the arrival of the analog delay, inexpensive harmonically-preserving pitch shifters started to appear, the most common of which were built into Variable-Speed-Control tape recorders (e.g., the Radio Shack VSC-1000, for dictation application. Although some of these devices may have found their way into effects boxes, pitch shifters arrived enforce into the music world with the digital delay lines of the 1980’s, starting with the Harmonizers by Eventide Clockworks, then followed by a host of other products by several manufacturers (such as the Vocalist series by Digitech). In addition, several pitch-to-MIDI converters have been optimized for the human voice (some old classics are the Fairlight VoiceTracker and the IVL Pitchrider), enabling MIDI sound sources to be driven by a vocalist. Modern voice processors are able to create nearly any type of real-time, dynamic harmony and correct off-key notes.

The vocoder (Voice Operated ReCorDER) combines two audio sources by imposing the dynamic frequency spectrum of one onto the other. The most common vocoder effect, a “talking” musical instrument made by superimposing human vocal utterances onto an instrument’s audio, was first attained by a device called a “talk box”, where audio from the instrument was piped, usually by a tube or neck-mounted speaker, into the player’s mouth, where it could be enunciated and picked up by a microphone. Steel guitarist Alvino Rey used a 1939 talkbox called the Sonavox to create his early “talking steel” hits. The first commercial talkbox was a device called “The Bag” made by Kustom in 1970, to be followed by a host of others. Although several bands used this device during the 70’s, such as Iron Butterfly, most people associate the talkbox’s sound with Peter Frampton.

The electronic vocoder was designed in 1940 by Homer Dudley of Bell Laboratories as a method of lowering the bandwidth required by telephone connections. Some large vocoders were built at research studios, such as the mid-50’s Siemens Studio in Munich. Commercial vocoders were built for music applications in the 70’s (e.g., the EMS devices and Harald Bode’s 7702, later built by Moog) and 80’s (e.g., the sought-after Dutch Synton devices, the Sennheiser VSM-201, the PAiA 6710 kit, the Korg devices with integrated keyboard). After Wendy Carlos’ soundtrack for A Clockwork Orange and Kraftwerk’s Autobahn album of the early 1970’s, the vocoder’s sound became part of popular music’s repertoire. Although analog vocoders are still manufactured, digital “phase vocoder” algorithms now are coded into many multi-effects processors or can run as real-time software packages.

Some aficionados still justify staying with the old analog gear, but all of the effects listed above, together with standard studio effects such as equalization and compression are now realized digitally in most instances. Real-time digital effects are rooted in academic research, such as the famous concerts in the 80’s by Pierre Boulez’s Ensemble Intercontemporain. During performance, their playing was analyzed, altered, and augmented in real-time with the 4X digital audio processor and synthesizer, designed at IRCAM in Paris by Giuseppe Di Giugno. The power of general-purpose computers has increased steadily since then. The 4X is long gone, but a considerable battery of real-time effects processors can now be run on a personal computer via downloadable audio “plug-in” software modules (independently developed programs that add functionality to major software applications). The technology will only improve, soon enabling a standalone desktop computer to act simultaneously as a very capable multi-timbral synthesizer, multi-channel effects processor, multi-track sequencer, and virtual recording studio.

From American Innovations in Electronic Musical Instruments
by Joseph A. Paradiso
© 1999 NewMusicBox

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