page_title: Dbx (noise reduction)
section_title: History
hierarchical_section_title: Dbx (noise reduction) / History
caption_attribution_description: English: Panasonic portable cassette player RQ-J20X with dbx noise reduction, 1983. From own collection. Taken by ProhibitOnions, 2007.
context_page_description: dbx is a family of noise reduction systems developed by the company of the same name. The most common implementations are dbx Type I and dbx Type II for analog tape recording and, less commonly, vinyl LPs. A separate implementation, known as dbx-TV, is part of the MTS system used to provide stereo sound to North American and certain other TV systems. The company, dbx, Inc., was also involved with Dynamic Noise Reduction systems.
context_section_description: The original dbx Type I and Type II systems were based on so-called "linear decibel companding" - compressing the signal on recording and expanding it on playback. It was invented by David E. Blackmer of dbx, Inc. in 1971.
  A miniature dbx Type II decoder on an integrated circuit was created in 1982 for use in portable and car audio, although only a few devices took advantage of it, such as certain Panasonic portable cassette players and Sanyo car stereos. dbx marketed the PPA-1 Silencer, a decoder that could be used with non-dbx players such as the Sony Walkman. A version of this chip also contained a Dolby B-compatible noise reduction decoder, described as dbx Type B noise reduction; this was possible after the Dolby patent (but not the trademark) had expired.
caption: The Panasonic RQ-J20X portable cassette player from 1982 was the first device to implement the dbx integrated circuit
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