How do records work?
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From the brains behind Brains On, this is the moment of um. Um, um, um, um, um, um.

Moment of Um comes to you from APM Studios. I'm Joy Dolo, a.k.a. DJ Dolo! Um...

You might know me as the host of Forever Ago, the most awesome history podcast for kids in the world. But I'm also an aspiring DJ. Last weekend, I DJed a birthday party for my friend's chihuahua, and it was incredible. I brought all my favorite dog records, You Ain't Nothin' But a Hound Dog, Snoop Dogg's greatest hits, and of course, Hula.

Who let the dogs out? Hoo, hoo, hoo, hoo, hoo. Great song. All the pups went wild when I played that one.

When I spin, I go old school. I don't use computers or even CDs. I use vinyl records. They're like big, black, flat plates. Here, want to see how it works? You just slap a record on this special machine called a turntable, and it spins them around. Then you place this little arm from the record player onto the record, and somehow it makes music.

I don't know exactly how it makes music, it just does. My buddy Ruby wanted to know about this too, so we asked someone who knows a lot about records.

Hi, my name is Josh Bonatti. I live in Brooklyn, New York, and I'm an audio engineer. I think most people can see when they hold a record that there are grooves on the record and that you have to place the record needle down into the grooves to hear any sound. The tools I use to make a physical record is something called a vinyl cutting lathe.

And it looks like a giant record player, basically. It looks like a big refrigerator with a record player sitting on top of it. And the machine that I'm using is basically step one of a three-step process in making a record. You have to make one master cut. That's step one. Then step two is you make a metal mold of that.

And step three is a record pressing plant, which takes the metal part and it's almost like a waffle iron where they can just start stamping out records made of plastic. If you were to be in my studio and watch me do this, I would take out a blank disc and I put this blank disc on the cutting lathe and then I would lower this kind of, it looks like a little small triangle that has

the cutting stylus on it and that lowers into this blank disc and cuts the groove from the beginning of the record until the end. I'm the one who's cutting the groove and then you're taking your turntable and you're placing your needle into that groove that I cut. Basically what's happening is as the needle is riding in the groove,

The grooves are essentially wiggling, and we call that modulation. The grooves are wiggling, and that is wiggling the needle. And so you have this mechanical movement, which is being transmitted into a very, very tiny electrical signal. And that electrical signal goes back to your stereo, and it is amplified automatically.

so that you can hear the music that's on the record. So when I'm making a master cut, I cut side A on one blank disc, and then I take another blank disc and cut side B. So all through the process, records are basically just one-sided until the very end at the pressing plant where they use these two metal molds, mold for A and a mold for B. They mount them into the machine.

you know, squish them together like the waffle iron and then you get a, get a double-sided waffle, right? There's a lot of, um, parallels between making waffles and making records. Um, um, uh,

So cool! So records have tiny little circular lines on them called grooves. These grooves look kind of like the rings on a tree stump. To play a record, you put it on a turntable, which is basically a machine that holds the record, and spins at a constant speed. On the turntable is an arm with a little needle on the end. When you touch the needle to a spinning record, it traces along those grooves in the record and vibrates.

those vibrations are turned into electrical signals, which the record player turns into sound waves that we can hear, like this. Okay, gotta get ready for my next gig, DJing my second cousin's hairdresser's housewarming party. DJ Dolo, out!

If you like this episode, take a second to subscribe to Moment of Um wherever you listen to podcasts. And if you want to learn more about the history of all kinds of awesome stuff, check out the Forever Ago podcast, where we have a whole episode all about the history of rap music. Want to see our shows come to life? Head to YouTube, where we've got awesome animated Brains On episodes. Search Brains On Universe on YouTube and subscribe.

If you have a question, we'd love to help you answer it. Drop us a line by going to brainson.org slash contact.

Moment of Um is produced by Molly Bloom, Rachel Brees, Rosie DuPont, Anna Goldfield, Ruby Guthrie, Mark Sanchez, Anna Weigel, Nico Gonzalez-Whistler, and Aron Moldeslassie. We had editing help from Shayla Farzan and Sandin Totten, and engineering help from Derek Ramirez. Our theme song is by Mark Sanchez. Our executive producer is Beth Perlman. The executives in charge of APM Studios are Chandra Kavati and Joanne Griffith.

Special thanks this week go to Hazel Barton, Emma Gerstenzang, and Josh Bonatti. See you next time, and the next day, and every weekday. Until then...