The signal from a tape player (or from a recording console, in case of direct-to-disc recordings) is fed to the disc cutter and modified to the RIAA recording characteristic. It is pre-sampled 1.1 seconds ahead of the main playback head to provide a control signal for the cutter-head radial drive, or the main cutter signal may be delayed. By this means groove spacing can be varied according to the amplitude of the signal, thereby achieving maximum playing time. Spacing can vary from 130 to 390 grooves per inch. A heated triangular chisel, actuated by two helium-cooled coils. cuts the groove in a lacquer-coated aluminum disc 14 inches in diameter for a 12 inch record and 10 inches for a 7 inch.
"I just wanted to let you know that I was very satisfied with the CD you made for me from a really old album my husband had. It is very clear and without background noise - he almost misses all that hissing. He was so excited to have it and couldn't believe I had found a place to transfer the music by looking on the internet. Thanks again,"