How is sound recorded onto a vinyl record??? I get the general concept that it’s in the grooves (pun not intended) and the needle plays it, but HOW is it recorded and played????? I just can’t grasp my head around it.
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I believe that they are pressed. You take a large press, fill it with pvc, and compress it into a mold that has the grooves.
The speed is consistent when played back. So they can calculate what noise the needle will make when it drags across grooves of certain size, shape.
This knowledge is factored into a specially calibrated cutting lathe, that interprets the recorded sound and determines how to cut grooves into a master record (which is then used as a template). It looks similar to a record being played but it is making the initial cuts to form the grooves.
This is how the term “cutting a record” originated.
Back in the day, the live sound would be interpreted by this machine to cut into the record, where pitch, volume and frequency would determine how the lathe moved and ultimately cut the record, but now the recorded sound goes through editing and mastering first.
Blow up a balloon and put it directly against your mouth and sing. Put your hand on the opposite side of the balloon and you’ll feel vibrations. Now imagine if you were to attach a needle to the balloon instead of your hand and you allowed the needle to scratch a groove into a spinning disc of wax. Now put the balloon to your ear and allow the needle to follow the groove, you would hear yourself singing.
Modernize it by using electromagnets to vibrate the needle as you sing into a microphone. Make a silicone mold of the wax copy, make a metal mold of the silicone mold. Record the B side of the record and make all those molds. Then place a pvc puck between the A side and B side molds and squish them together. Boom, vinyl record.
You scratch a sharp needle extremely precisely in to the vinyl, and when you run a needle through these scratches it creates a sound, which you can actually hear from some vinyl players by just having the record spin with the needle down without a speaker system
Usually this kind of question gets removed due to Rule 7 (search first). Search this sub for vinyl or speakers.
First you should watch [the Animagraffs animated explanation of how sound & speakers work](https://youtu.be/RxdFP31QYAg?t=156). It will help you understand that sound is not nearly so complicated as you think it is. It’s just back-and-forth motion of the air!
Technology Connections recently made [an explainer for vinyl records](https://youtu.be/3DdUvoc7tJ4?t=101), although it is not quite as simplified as I’d like. I’m still on the lookout for a 100% technically accurate, visually appealing, and not-too-wordy video that explains records.
Anyway, here’s my attempt at a simple explanation:
Air is kind of springy. So is your eardrum. All sound you hear is ultimately just your brain’s interpretation of the simple back-and-forth vibrations of the air in each ear. These vibrations also result in miniature changes in air pressure.
You might see these vibrations drawn as a graphical wave, with the horizontal scale being time, and the vertical scale showing the air pressure rising and falling above a neutral baseline.
If you jiggle a magnet inside a coil of wire, or jiggle a coil near a magnet, it generates (or modifies) electricity in the wire, and the voltage (pushing force) of the electricity fluctuates exactly in the same way as the motion of the coil/magnet apparatus. This, too, can be graphed in the same way, e.g. with an oscilloscope, only now the vertical scale represents an electrical voltage, which happens to look almost exactly the same as the air pressure graph.
If you gently move a needle across the radius of a rotating disc coated in a soft material, it’ll carve a spiral groove. You can use magnets and coils to jiggle it side-to-side while doing this, such that the walls of the spiral groove undulate, thus creating an exact recording of the jiggling. This is what happens in the lathe that carves the master disc which is the basis of molds for each side of a record.
From such master/”matrix” discs, you can make a set of metal molds and put them in a hydraulic press to squish a glob of vinyl (plastic) into a flat disc, impressing a copy of the groove into it. The resulting record has a copy of one mold on one side, and the other mold on the other side.
Now in your playback system, you can let a stylus ride in the groove as the disc rotates. The groove walls will jiggle the stylus side-to-side, and the magnets & coils attached to the stylus will generate a weak electrical current with voltage variations matching the jiggles.
You can feed this signal to a phono pre-amp to clean it up a bit, and then to an amplifier to make it loud enough to drive your headphones or loudspeakers, which are basically another coil-and-magnet system attached to a cone which pushes air back-and-forth just like the original instruments & voices did.
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