What exactly is London/Decca


I'm hoping someone may enlighten me on what exactly a London/Decca "Phase 4" record is. At first, I thought it must be a quadraphonic record, but I've picked up a few and they aren't. Most seem to be from the late 60's. One came with a promotional insert that describes it as a "marvel of sound" (not particularly enlightening). Might anyone know what the difference is between a "Phase 4" London/Decca and any other non-Phase 4 London/Decca record? Tks.

John
john_adams_sunnyvale
Rushton is quite right in his explanation of Phase 4 recordings. I have been purchasing a few of these lately, and to me they are more thrilling to listen to than SACD Classical recordings. Some of the ones I particularly am enjoying is Stanley Black/Beyond The Sea, Ronnie Aldrich's twin piano recordings, and several from Werner Mueller. Some of the stuff is kinda wild and different. Try some and enjoy!
Rushton - thanks so much for your fulsome response. I'm a classical enthusiast who is new to vinyl, so I'm fascinated about learning more about the classical labels, their histories, technical merits, etc. Have you found anything on the web or elsewhere that you have found insightful or interesting on this subject? Thanks again.

John