Master tape - record matrix insights

A record matrix can only be used to make a limited number of pressing dies and a number of matrices must be made from each processing master tape depending on the number of records to be manufactured. To make a new matrix, the processing master tape must be used to drive the cutting lathe again and sometimes adjustments in the groove cutting parameters are made. Each matrix made is numbered sequentially and stamped on the matrix as S-1, S-2, S-3 and so forth. Most of this information is shown in the embossed number at dead wax. 

As example the RCA LSC 2455, a Schumann piano concerto played by Van Cliburn with Reiner and the Chicago Symphony. The embossed numbers code are: LSC 2455 Side 1 L2 RY 2136 10S, Side 2 RY 2137 6S. Where L=the year in which the master tapes were made, R=for classical selections, Y=for stereo pressings, 2136=the annual sequence number of the processing master tape used for that side, and 10S=the sequence number of the record matrix for that side. Therefore, for LSC 2455, the record was mastered in 1960. It is a stereo classical recording. Side 1 was made from the 2136th master tape made in 1960 and pressed with a stamper made from the 10th matrix. - Saulo Zucchello