CX (noise reduction)

[4] CX was originally designed by CBS as a noise-reduction technology for vinyl LP records,[5][4] similar to the earlier dbx disc (based on dbx II) and High-Com II systems, but, like the later UC system, it aimed at the lower-cost consumer mass market rather than high-end audiophile niche markets only.

Classical guitarist Liona Boyd demanded that the CX encoded version of one of her albums be withdrawn because of perceived shortcomings, even though Jamieson claimed that CBS had the technical means to overcome such objections.

[10] Based on an UREI reference design published by CBS,[11] many third-party builders of CX decoders used a dual operational transconductance amplifier 13700D made by JRC (today NJR),[12][13][14][15][16][11] coupled with a pair of quadruple JFET operational amplifier chips TL084 in their designs.

[11] In 1982, the CX integrated circuit U2141B was developed by AEG-Telefunken, Germany, by Ernst F. Schröder, Dietrich Höppner and Kurt Hintzmann,[2] the same team who previously designed the High Com noise reduction system,[2][17] a broadband compander with up to 20 dB of noise reduction.

[4] In Europe, many CX discs were manufactured in the Netherlands with the catalog number prefix "CBSCX".

These changes were made because, at the time of CX's adoption on LaserDisc (1981), the vast majority of program sources used for mastering, such as 35 mm optical and magnetic film soundtracks, as well as the 2-inch IVC-9000 and the 1-inch C-Type videotape formats used for LaserDisc mastering, had signal-to-noise ratios low enough that undecoded playback would accentuate their noise to unacceptable levels.

[citation needed] By reducing the total amount of noise reduction and modifying other aspects of the CX system to better match LD's FM audio shortcomings, undecoded playback sound quality was maintained and vastly improved decoded sound was achieved at the same time.

A look at Pioneer's catalogs as late as 1987 shows that the majority of titles did not have CX encoded analog sound - most were not digital either.

Although RCA improved the plastic/carbon formulation used to make discs, which lowered disc noise levels by 3 dB, and modified the mastering system, the CED format still required the full 20 dB of noise reduction that was achieved with the unmodified LP system.

[23][24] CX was used in FMX, a commercially unsuccessful noise reduction system developed in the 1980s for FM broadcasting in the United States.