Editing Quadraphonic sound (section)

==== UD-4 / UMX / BMX ====

''[[UD-4|UD-4/UMX]]'' was developed by Nippon/Columbia ([[Denon]]). This is a hybrid discrete/matrix system. Only 35 to 40 items are encoded in this format and it was marketed only in the UK, Europe, and Japan.

The short-lived system suffered from incompatibility with regular stereo playback due to phase differences between the left and right channels.<ref>{{cite magazine |last=Cooper |first=Duane |author-link1=Duane H. Cooper |title=The UD-4 System |url=http://www.quadraphonicquad.com/QQ-ud4_hifi.htm |magazine=Hi-Fi News & Record Review – March 1975 |access-date=5 February 2012}}</ref> UD-4 was less critical in its setup than CD-4 because the carriers did not have to handle frequencies as high as those found in the CD-4 system.<ref>{{cite journal |last1=Cooper |first1=Duane H. |author-link1=Duane H. Cooper |last2=Shiga |first2=Takeo |title=Discrete-Matrix Multichannel Stereo |url=http://decoy.iki.fi/dsound/ambisonic/motherlode/source/Discrete_Matrix%20Multichannel%20Stereo%20Duane%20Cooper%201971.pdf |access-date=September 28, 2018 | journal=Journal of the Audio Engineering Society |volume=20 |issue=5 |pages=346–360 |date=June 1972 |publisher=[[Audio Engineering Society|AES]]}}</ref>