Browse by Spelling

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

D/A Converter
D1 Video
D2 Video
DA88
DA98-HR
DASH
DAT
Data Compression
Data Migration
Datasat
DAW
dB
DBC
dBFS
DBX 700
dbx®
DCT
DD+
De-esser
Decay
Decibel
Decibels Full Scale
Decode
Degauss
Delay
DFTC
Dictaphone
Digibeta
DigiDelivery™
Digital Audio
Digital Audio Tape
Digital Audio Workstation
Digital Betacam
Digital Linear Tape
Digital Noise
Digital to Analog...
Digitization
Dipped
Distortion
Dither
DLT
DME
Dolby® "W"
Dolby® A
Dolby® B
Dolby® C
Dolby® Digital
Dolby® Digital EX™
Dolby® Digital Plus
Dolby® E
Dolby® NR
Dolby® ProLogic
Dolby® ProLogic IIx
Dolby® SR
Dolby® Stereo
Dolby® TrueHD
Doubling
Downmix
Drift
Drop-frame Time Code
Dropout
Dry
DTRS Cassette
DTS
DTS-ES
DTS-HD High-resolution...
DTS-HD Master Audio
DTS-NEO:6
DVD
Dx
Dynamic Compression
Dynamic Processing
Dynamic Range

Dbx®

From Wikipedia

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. 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.

Developed in 1971, companding noise reduction works by first compressing the source material's dynamic range in anticipation of being recorded on a relatively noisy medium such as magnetic tape. Upon playback, the encoded material, now presumably “contaminated” with noise, is passed through an expander, which restores the original dynamic range of the source material. The contaminating tape hiss should now be masked by the dynamic expansion process, resulting in a significant reduction in perceived noise.

A noticeable artifact of dbx was "breathing;” 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 rival Dolby® because dbx's compander was more aggressive and worked across the frequency spectrum. Due to dbx's high compression and strong high-frequency pre-emphasis, dbx-encoded tapes sound very harsh when played back undecoded.

dbx Type I was widely adopted in professional recording, and Tascam incorporated dbx Type II in their Portastudio four-track cassette recorders, which became an industry standard for small recording studios at the time. 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, and although it also used some companding, the level of compression and expansion was very mild, so that the sound of Dolby-encoded tapes was acceptable to consumers when played back on non-Dolby equipment.

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. 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. dbx encoded LPs had, in theory, a dynamic range of up to 120db. In addition, dbx LPs were produced from only the original master tapes, with no copies being used, and pressed only on heavy, virgin vinyl. Most were released in limited quantities with premium pricing. Until the CD format came along in 1982, dbx LPs were the quietest and highest fidelity mass-market audio format available to consumers.

A few films used dbx noise reduction in post production, including Apocalypse Now, but Dolby noise reduction dominated that market.

This definition is licensed under the GNU Free Documentation License found at http://www.gnu.org/copyleft/fdl.html . It uses material from the Wikipedia article at http://en.wikipedia.org/wiki/Sine_wave.