Editing Dbx (noise reduction) (section)

==History==
[[Image:Panasonic RQ-J20X 20070627.jpg|thumb|right|The Panasonic RQ-J20X portable cassette player from 1982 was the first device to implement the dbx integrated circuit]]
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.<ref name="Hoffman_2004"/><ref name="Blackmer_1972"/>

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.<ref>{{cite web |url=http://pocketcalculatorshow.com/walkman/walkman-db.html |title=The Pocket Calculator Vintage Walkman & Portable Stereo Database |access-date=2016-02-09 |url-status=dead |archive-url=https://web.archive.org/web/20120620161144/http://pocketcalculatorshow.com/walkman/walkman-db.html |archive-date=2012-06-20}}</ref> dbx marketed the '''PPA-1 Silencer''', a decoder that could be used with non-dbx players such as the [[Sony Walkman]].<ref>{{cite web |url=http://pocketcalculatorshow.com/walkman/museum.html |title=Pocket Calculator's Vintage Walkman Museum |access-date=2016-02-09 |url-status=dead |archive-url=https://web.archive.org/web/20120817122103/http://pocketcalculatorshow.com/walkman/museum.html |archive-date=2012-08-17}}</ref> A version of this chip also contained a [[Dolby noise reduction|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.

Software implementations have been developed.<ref name="DAFx_2004"/><ref name="u-he_2018"/><ref name="Hess_2018"/><ref name="Dyson-Hess_2019"/>