Transcription
Record players were way ahead of their time. Everyone knows that. The sound comes from the grooves, but how on Earth can a groove in a plastic frisbee generate the sweet ear nectar that is Yellow Submarine?
It's because sound is just vibration. Say you were to speak into a big horn that had a stretched out balloon at the end. That stretched out balloon is going to vibrate along when you speak into said horn, and that vibration is the same vibration your eardrum makes to let you hear sound. So say you then taped a pencil that would vibrate with the balloon. If I put a piece of paper against the pencil, you'd see something like this: useless scribbles.
Now, if I move the piece of paper at a constant pace, you'd see this: slightly less useless scribbles. Congratulations, you just recorded your voice. Good job. That scribble on your piece of paper is the sound waves or vibration that you were making by speaking into the horn. But there's no way to play it back. It's literally just a piece of paper.
Only, what if it wasn't? What if instead of making a 2D line, we make a 3D line? And that's what these guys did back in the 1800s: the gramophone. Say Lady Gaga sings into a big horn that would focus and direct the sound onto a diaphragm, which is essentially just a fancy stretched out balloon from before. The diaphragm would vibrate, and attached to the diaphragm would be a stylus or needle that would cut these vibrations into a wax record, creating a 3D line with bumps and valleys.
If you take that wax record and put it through a chemical bath, you'll have a metal record. You can then use that metal record as a stamp on old plastic frisbees. Now we have a record, but the question still stands: how does it play music? You actually literally just do everything backwards. First, start spinning the disc at the same speed you spun the wax record when recording. Then, drop the needle into the groove. The bumps and valleys are going to cause that needle to make the exact same vibrations as the needle that recorded the original sound.
And just like how you record the original sound, the needle is connected to a diaphragm, and that diaphragm is going to make the exact same vibration as the original recording. And vibration is sound. So all we need to do is amplify that vibration by adding a comically big horn, and you'll get the exact same sound made by Lady Gaga.
But modern records don't use big horns, so how does that work? Well, modern record players are a little bit more digital. Instead of a horn, it's a speaker, and instead of a flimsy balloon, it's a copper coil vibrating in between two magnets. As the copper coil moves between the two magnets, it makes electricity that goes to a speaker, creating sound.
But it's the 80s, and only losers use vinyl anymore. The cassette tape. Now, what sort of sorcery is used to put Michael Jackson into this measly piece of black Scotch tape? Magnets. The answer is magnets. In fact, the actual process is kind of just a futuristic magnetic version of a vinyl.
Step one: record some music. Say your Michael Jackson. As Michael Jackson, you aren't going to sing into some big horn. You're going to sing into a microphone. How can a microphone capture your hees and hahas? Well, let's get it open. Inside of the microphone, you'll find a diaphragm that vibrates when you speak into it, just like the balloon. The diaphragm is either connected to a copper coil, kind of like the record player, where the sound vibrates the coil, sending different strengths of electricity, or the diaphragm is connected to a capacitor, which is basically just a fancy plate. As you speak, the diaphragm moves, and this vibration changes the distance, causing a change in stored energy, resulting again in different strengths of electricity.
Step two: magnets. So now we have electricity. How does that help? Well, it's easier to think of the electricity as the pencil in our original example, and that makes the magnetic tape the paper. The recording head is the point of contact. The different strengths of electricity make changes to the magnetic fields on the tape surface. This creates a little pattern of magnetization that almost exactly replicates the original sound wave.
But how do we read said magnetization? Well, just like before, it's the same process but backwards. Put your tape into a boom box, and there will be a playback head there too. As the tape passes over the playback head, the changes in the magnetic field on the tape make an electric signal. This is the same electric signal that was made when recording. The electricity is sent to a speaker, which has a diaphragm, just like the microphone, creating a big old vibration, and thus you hear the sweet harmony that is Michael Jackson.
But nobody listens to Michael Jackson, cuz he is just so 10 years ago. Welcome to the '90s. Now, instead of a frisbee or Scotch tape, we use a fat, glorified ring to record sound onto. This fat ring. We use a microphone that works the same way as before, except this time we take that electricity and convert it into ones and zeros that represent the original sound wave. And that's a lot of words. So how the freak do we do that? By looking at the voltage. For example, if the voltage is this high, we give it a one. If it's this low, we give it a zero.
Now, using a teeny laser, we put these ones and zeros on a disc where a pit represents a one and an untouched land represents a zero. But these pits and lands are so small, the disc seems smooth. Now, if you put this disc into your crusty 1992 Honda Accord, it's going to read it also with a laser. This laser bounces off the CD. If there's a pit, it bounces a bit differently and writes down a one. There's a land, it bounces the same and writes down a zero.
But how do these ones and zeros magically become music again? Same thing but backwards. First, we use a digital to analog converter, but you can just call him DAC. DAC will generate a certain amount of electricity depending on whether it reads a one or zero. This creates the same electric stream that was in the microphone when originally recording. And just like before, the electric stream is sent to a speaker, which has a diaphragm that vibrates depending on how much electricity it receives, creating weak knees, heavy arms, and Mom's spaghetti and all that.
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