Something that’s bugged me for a while now… How exactly do you imprint, if that’s the right word, music onto vinyl so that the needle can pick it up and play it?
Short version: you make a master disc out of metal, with the grooves correctly inscribed in it, and then you use the master to press the grooves into pieces of vinyl, like those Christmas cookie stampers that make designs on the top of the cookie.
A bit longer version:
A lacquer (an aluminum-based disc covered by plastic) is cut with a special turntable (called a lathe) using a cutter head that tracks in true tangential fashion across the disc. The lacquer is then electroplated with nickel to form a master. Think of a lacquer as a ‘positive’ and a master as a ‘negative’; the lacquer has grooves, the master has ridges. The master is then electroplated to make mothers (positives) which are, in turn, electroplated to make stampers (negatives). These stampers are used to press the vinyl records.
It may seem like a couple more steps than are actually needed, but consider:
A stamper can only be used a limited number of times before the quality of the pressings will begin to fall off (in some cases, where the highest quality is demanded, the stampers are only good for 500 pressings). As only one master can be created from a lacquer, if you use the master for pressing, and you want to maintain the highest quality, you can only press 500 vinyls. By using the master to produce multiple mothers and stampers, you’ve given yourself the opportunity to increase your high quality pressing substantially.
For a more, check out Record Technology Incorporated
In the days before the advent of tape recorders, home machines which cut acetate disks were actually sold. My grandmother had a couple of disks of her brother playing an organ which had been recorded on a home machine. The sound quality was horrid. Here’s a description of one of the home disc recorders: