RCA Living Stereo - Audiophile Sampler

On October 6, 1953, RCA Victor held experimental stereophonic sessions in New York City's Manhattan Center with Leopold Stokowski conducting a group of New York City musicians in performances of George Enescu's Roumanian Rhapsody No. 1 and the waltz from Tchaikovsky's opera Eugene Onegin. In February 1954, RCA Victor made its first commercial stereophonic recordings, taping the Boston Symphony Orchestra, conducted by Charles Münch, in a performance of The Damnation of Faust by Hector Berlioz. This began a practice of simultaneously recording orchestras with both stereophonic and monaural equipment. 

Initially, RCA used RT-21 quarter-inch tape recorders (which ran at 30 inches per second), wired to mono mixers, with Neumann U-47 cardioid and M-49/50 omnidirectional microphones. Then they switched to an Ampex 300–3 one-half inch machine, running at 15 inches per second (which was later increased to 30 inches per second). These recordings were initially issued in 1955 on special stereophonic reel-to-reel tapes and then, beginning in 1958, on vinyl LPs with the "Living Stereo" logo. RCA has continued to reissue many of these "Living Stereo" recordings on CD.

https://en.wikipedia.org/wiki/RCA_Records