Electromechanical music is music that is produced through a combination of electronics and actual physical movement (mechanics). While fairly uncommon nowadays (as electronic music is generally produced with pure electronic devices), many pioneering instruments from the 1800s and early 1900s produced sound electromechanically. Some of these instruments include the Telharmonium, the Hammond organ, and the Electromechanical Piano. Electromechanical instruments can be divided roughly into three categories:
- Accoustic instruments that can function without electricity, but the inclusion of electrical components makes the more convenient to play.
- Modified instruments of accoustic instruments that use accoustic principles to produce their sound, but are only barely audible without amplification.
- Instruments that rely on an electrical component to produce any sound at all.
Accoustic Instruments with Electrical Components Edit
The first category includes instruments that rely on significant amounts of air pressure, the canonical example of which is the pipe organ. Although it is certainly possible to hand-pump a pipe organ (after all, the pipe organ existed centuries before electric power systems did), it is very labor-intensive and cannot be done by the performer while playing. Performing a long piece might have, in past centuries, required several teams of workman to pump the bellows to produce air pressure for the organ. Substituting an electrically driven compressor greatly improved the availability of pipe organ playing time, and made it practical to install pipe organs in more venues. Additionally, some organs use electric solenoids, or electrically-driven pneumatic valves, to operate the organ's pallet valves and stops.
Another example of the first category is an instrument known as the glass harmonica. This consists of wheels or bowls of glass of different sizes, all mounted coaxially on a spinning shaft. The performer presses a wetted finger or thumb to the rim of the spinning glass to produce sound. The instrument traces back to the 18th century. Originally, the motive power was provided by the performer, sometimes by turning a crank, which obviously left only one hand for playing. Another mechanism used a treadle mechanism, but with this it was difficult to maintain a constant speed, and it was tiring to the performer. Adding an elecric motor makes the instrument much more convenient to play.
Finally, a number of sound-making devices which are not usually thought of as musical instruments, but do sometimes have musical uses, use electromechanical principles. Buzzers, sounders, and alarm bells all rely on motor-driven or solenoid-driven mechanisms to make a beater or clapper strike repeatedly.
Late 19th-century and early 20th-century automata often featured musical instruments being played mechanically. Some of this was electrically powered, although much of it was not.
Modified Accoustic Instruments Requiring Amplification Edit
These are often instruments which conventionally have a resonant body to accoustically amplify the waveform produced by a vibrating element, such as a string, bar or reed, but the resonant body has been removed -- either replaced with a non-resonant solid body, or just missing. The most common example, although it is seldom thought of as an "electromechanical" instrument, is the solid-body electric guitar. Practically all of the sound from such a guitar comes from the signal picked up by a magnetic or piezoelectric pickup, and then fed to an amplifier. Without the amplification, the guitar can barely be heard. Numerous variations on this theme exist, such as the Chapman Stick, or Eddie Jobson's body-less electric violin.
Somewhat closer to being thought of as an electronic instrument is the electromechanical piano. The best known example of such is the electric piano invented by Harold Rhodes, and sold at various times under both his name, and the Fender guitar brand. The Rhodes piano uses a miniature version of a conventional piano's hammer mechanism to strike a small tuning-fork-like element. A magnetic pickup detects the vibrations of the element and sends the signal to an amplifier. The Wurlitzer electric piano uses a similar hammer mechanism to strike small metal bars. (In both cases, the apparent note played sounds lower tan what would be expected, given the size of the struck element, due to the missing fundamental effect,)
Instruments Relying on Electrical Components Edit
This category includes instruments which have both electric and mechanical components, but cannot produce any sound with electrical power. The two most prominent were mentioned in the introduction -- the Hammond organ and the Telharmonium. The Hammond organs used a mechanism known as a tonewheel to produce waveforms. The tonewheel was a small metal disk with a magnetic pickup positioned at its edge. The wheel was cut so that as it rotated, the edge would alternately move towards and away from the pickup, producing a waveform. Unlike, say, the glass harmonica, this method of producing sound is fundamentally electrical in nature, requiring both the magnetic pickup, and a synchronous electric motor to spin the wheels at a precise speed so that the instrument remains in tune. And, because the Hammond organ is a sort of additive synthesis machine, the signals from the wheels are routed through a complex switching mechanism to choose the harmonics that will be output for a given note. And finally, the electrical signal has to be amplified and fed to a loudspeaker before it can be heard.
The Telharmonium was essentially a proto version of the Hammond organ. It was conceived in the early 20th century before any means of amplifying an electrical signal was known. So, instead of small tonewheels, the Teleharmonium had a huge bank of alternating-current generators, all spun by a very large motor. The generators were to create a signal of high enough voltage and amplitude that they could be fed directly to one or more loudspeakers (it was conceived that it would be connected to telephone networks for distribution of the music it produced as it was played).
Another group of instruments in this category are ones that involve passing a strip or loop of magnetic recording tape, containing a pre-recorded sound, across a playback head. The Mellotron is one such; it has a motor driven capstan that pulls a strip of tape across a playback head when a key is pressed, and a spring-loaded mechanism that pulls the tape back when the key is released. Several recordings have used improvised versions of this involving a multi-track tape machine and a recording console, with which notes are "played" by moving the faders on each track. The Alan Parsons Project actually had a machine built to do specifically this, called the Projectron. A whole category of electronic music (seldom practiced now) revolved around recording, manipulating and playing back tape; it was called the tape studio.
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