Introduction:

To every person who has read the "Technical Information" box on the jacket liner notes of an LP record, the names Scully, Presto, Neumann, Westrex, Grampian, HAECO, Pultec, Langevin, Fairchild, Altec, Capps, Transco, Audio-Devices, Soundcraft and others may be familiar, almost household names.

These were all manufacturers of equipment and supplies that touched the process of making phonograph records, from the stage of being converted from a "master" to a release pressing intended for home playback.

The Lacquer Channel

It all starts with the disc recorder or "lathe" as it is often referred to... a precision piece of equipment designed with a slowly rotating feed screw mechanism and carriage to uniformly move a cutting head across the radius of the disc. The accurately shaped cutting stylus, mounted in the head, cuts a VERY precise spiral groove across a flat lacquer coated aluminum disc spinning at an exact speed of 33-1/3, 45, or 78.26 revolutions per minute, the standard phonograph operating speeds. Scully, Presto and Neumann are probably the best known manufacturers of disc recording lathes.

There were instances of early recordings (mostly acoustical) that played at speeds as low as 60 rpm, and as high as 90 rpm, but by the time electrical recording replaced acoustical, standard speeds were adopted.

Article courtesy of audio-restoration.com