The most common implementations are dbx Type I and dbx Type II for analog tape recording and, less commonly, vinyl LPs.

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.

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.

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.

dbx Type I and Type II are types of " companding noise reduction ".

Because dbx Type I and Type II are broadband ( single-band ) companders ( unlike Dolby-A's four bands ), they are susceptible to audible noise modulation and other artifacts.

In the control signal path, the dbx Type II process rolls off the high and low frequency response to desensitize the system to frequency response errors – since the roll-off is only in the control path, it does not affect the audible sound.

* dbx Type I was widely adopted in professional recording, and Tascam incorporated dbx Type II in their Portastudio four-track cassette recorders.

* An advantage of dbx Type I and Type II compared to Dolby noise reduction is that it did not require calibration with the output level of the tape deck, which could cause incorrect tracking with Dolby B and C, leading to muffled high tones.

dbx-TV noise reduction, while having elements in common with Type I and Type II, is different in fundamental ways, and was developed by Mark Davis ( then of dbx, now of Dolby Labs ) in the early 1980s.

Dual-ended systems ( such as Dolby B, Dolby C, Dolby S, dbx Type I and dbx Type II, High Com and High Com II as well as Toshiba's and JVC's ) have a pre-emphasis process applied during recording and then a de-emphasis process applied at playback.

* dbx 160X Compressor – " I use a compressor live, but only because sound guys seem to like it when I have one onstage, even if it's on bypass.

However, unlike Dolby and dbx Type I & Type II noise reduction systems, DNL and DNR are playback-only signal processing systems that do not require the source material to first be encoded, and it they be used together with other forms of noise reduction.

Other examples include dbx, Inc .' s Model 700 system, which, similar to modern Super Audio CDs, used a high sample-rate delta-sigma modulation rather than PCM ; Decca's 1970s PCM system, which used a videotape recorder manufactured by IVC for a transport ; and Mitsubishi's X-80 digital recorder, a 6. 4 mm ( ¼ in ) open reel digital mastering format that used a very unusual sampling rate of 50. 4 kHz.

* dbx ( noise reduction ), a rival system

The main alternative to Dolby was the dbx noise reduction system, which achieved a high signal-to-noise ratio, but was essentially unlistenable when played back on decks that lacked the dbx decoding circuitry.

When employed on LPs, the dbx Type-II system reduced the audibility of dust and scratches, reducing them to tiny pops and clicks ( if they were audible at all ) and also completely eliminated record surface noise.

A modified version of dbx was also used in the Colortek stereo film system.

In addition, dbx Type-II noise reduction was used in the Model-II and Model-III variants of MCA's Sensurround Special Effects System on the optical audio track and was a cornerstone of the entire system.

dbx modules that were set for 3: 1 were used to increase the dynamic range of the system.

dbx is best known for the dbx noise reduction system.

The dbx noise reduction system used compression while recording an audio track and symmetric expansion when playing it back.

One feature of the dbx system was an inbuilt noise-gate, to just shut off anything below a certain decibel level.

David E. Blackmer ( 11 January 1927-21 March 2002 ) was an American audio electronics engineer, most famous as the inventor of the DBX noise reduction system and founder of dbx, Inc ..

** dbx ( noise reduction ), a noise reduction system invented by dbx, Inc.

Dbx was the competing analog noise reduction system developed by dbx laboratories.

Band members Walter Becker and Donald Fagen were unhappy with the album's sound quality owing to an equipment malfunction with the then new dbx noise reduction system.

dbx is a family of noise reduction systems developed by the company of the same name.

dbx Type-II is for more noisy media that have a lower S / N and much more restricted frequency response.

dbx, Inc. is an American producer of professional audio recording equipment.

Earthworks is a professional audio equipment company founded by David E. Blackmer in the late 1980s after he left dbx to sell studio microphones, preamplifiers and studio reference monitors.

With noise reduction typical signal-to-noise figures of 70-76 dB with Dolby C, 80-86 dB with Dolby S, and 85-90 dB with dbx could be achieved.

dbx marketed the PPA-1 Silencer, a decoder that could be used with non-dbx players such as the Sony Walkman.

Compandors are used in concert audio systems and in some noise reduction schemes such as dbx and Dolby NR ( all versions ).

Although it brought extraordinary dynamic range to the lowly cassette tape, dbx noise reduction did not achieve widespread popularity in the consumer marketplace, as compressed recordings did not sound acceptable when played back on non-dbx equipment ; Dolby B was already widely used when dbx was introduced.

dbx was also used on vinyl records, from 1973 until around 1982, and over 1100 albums were released with dbx encoding, which were known as dbx discs.

In addition, dbx LPs were produced from only the original master tapes, with no copies being used, and pressed only on heavy, virgin vinyl.

dbx noise reduction, capable of more than 20 dB of noise reduction, was used in the re-recording of the film Apocalypse Now in 1979.

MCA's Sensurround + Plus, used on the film Zoot Suit, employed dbx Type-II with the 4-track magnetic sound format on 35mm film prints, providing the motion picture with a stereo soundtrack capable of wide dynamic range and freedom from noise.

Due to the use of dbx Type-II noise reduction, MCA eliminated the standard Academy Filter traditionally used on optical prints, thus giving Sensurround an increased frequency response of 16 Hz to 16 kHz and a dynamic range of 86 dB, superior to 70mm magnetic prints of the time.

* Outlook Express 5. 0, which was included in Windows 98 Second Edition ( SE ) ( June 1999 ), switched to *. dbx files, with a separate file for each mailbox folder.

* Outlook Express dbx file format by Arne Schloh-a partial documentation of the DBX file format with sample code

* Outlook Express 5. 0 file format-another reverse-engineered. dbx document with sample code

Each channel strip included dbx type-1 noise reduction and semi-parametric equalizers ( with fixed bandwidths ).

The company – dbx, Inc. – was also involved with Dynamic Noise Reduction ( DNR ) systems.

A sometimes noticeable artifact of dbx was " breathing ", as its compander rapidly increased and decreased the volume level of the background noise along with the music, which was most noticeable in quiet musical passages ; this was a greater issue with dbx than with Dolby because its compander was more aggressive and worked across the frequency spectrum.

Undecoded dbx playback also exhibited large amounts of dynamic error, with audio levels going up and down constantly, making it a very fatiguing experience.