Eltro information rate changer

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The Eltro information rate changer was an analog recording tool used to modulate pitch without changing speed and vice-versa. Patents for the device date back to the 1920s.[1] The Eltro was the first technology capable of changing audio pitch (frequency) and speed (time) independently from one another.

The technology was developed in Germany by engineer Anton Marian Springer (1909-1964).[2] The Eltro was an accessory device that worked in conjunction with a reel-to-reel tape recorder. Recorders compatible with the Eltro became widely available in the 1950s. The device was first publicly demonstrated in 1953. By the mid 1960s the Eltro was a relatively common piece of equipment in many recording studios.

It was often used to adjust the timing of radio commercials. A 30 second commercial must be timed to exactly 29 seconds in order to fit precisely into radio station playlists. By using the Eltro a recording engineer could have greater control over the precise length of a commercial, while at the same time leaving pitch unaltered. It could also be used for a variety of musical effects.

Musician and recording engineer Wendy Carlos used an Eltro Mark II machine at Gotham Recording Studios in New York City in the 1960s.[3] The Beach Boys used it to create high pitch vocal effects on the song She's Goin' Bald recorded in Los Angeles in 1967.

The Eltro is probably best known from use in the 1968 film 2001: A Space Odyssey.[1][4] The effect of the Eltro was applied to the voice of actor Douglas Rain, playing the part of the HAL 9000 computer. In the film, both the pitch and speed of HAL's voice gradually drop at different rates while the computer is deactivated.

The Eltro processed one audio channel at a time and was only capable of working with mono recordings. It fell out of common use during the 1970s. Later devices were developed to shift pitch by using a variety electronic technologies. Many of the later technologies were stereo capable. With the widespread availability of digital recording in the 1980s it became possible to more easily control pitch and speed with software, while avoiding expensive and highly specialized analog equipment. Digital audio workstation software can now achieve the same effects more easily and at lower cost.

See also[]

References[]

  1. ^ a b Langford, Simon (2013). Digital Audio Editing: Correcting and Enhancing Audio in Pro Tools, Logic Pro, Cubase, and Studio One. CRC Press. p. 239. ISBN 978-1-134-11130-5.
  2. ^ https://soundandscience.de/contributor-essays/anton-springer-and-time-and-pitch-regulator
  3. ^ "The Eltro Mark II Information Rate Changer".
  4. ^ Krapp, Peter (2011). Noise Channels: Glitch and Error in Digital Culture. University of Minnesota Press. p. 65. ISBN 978-0-8166-7624-8.
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