In the age of streaming music, it might be an odd question to ask how a record play works. But the magic of the record player is continuing to sway people to an older and, arguably, more cumbersome format. What is it about a record spinning on a turntable that keeps our eyes amused and our ears and hearts warmed? We take a look at how a record player works, and how your favorite artists can seemingly be conjured from a mere piece of plastic.
Teaching wax to speak: The origin of records
A photograph of Thomas Edison with his second phonograph in 1878. Levin Corbin Handy/Public Domain
Let’s start by going back — way back. It’s the middle of the 19th century and a French inventor, Édouard-Léon Scott de Martinville, has discovered that he can create a physical transcription of sound by running a bristle gently across the surface of a smoke-blackened piece of paper or glass. The bristle was connected to a flexible diaphragm that would vibrate when hit by sound, which in turn caused the bristle itself to vibrate, making marks on the piece of paper or glass. As fascinating as this development was, there was no way to reproduce, or playback, the audio after recording; it was purely for visual analysis.
It wasn’t until the 1870s that a gentleman named Thomas Edison realized that if he could record the movements correctly he could then reproduce them. Edison’s invention, the phonograph, worked by rotating a wax cylinder (see photo, above) at speeds of up to 160 revolutions per minute (rpm) while dragging a needle across it. If the needle was sharp enough and enough pressure was applied, the needle could cut into the wax. If, at the same time, the needle was vibrated by a person speaking into a mouthpiece that was connected to it, the sound waves could be recorded as cut grooves.
To play the recording, one would substitute the more substantial cutting needle for a lighter playback needle with less pressure. Now, the needle would ride through the grooves, vibrating the diaphragm; this would cause a sound to be produced as it moved air, and the use of an attached horn would amplify the sounds. This process was the key to any record at the time.
Vinyl records and speakers: How your record player works
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But how does your modern turntable work? Your record player likely doesn’t have a horn or spinning cylinder, so how does it reproduce sound? As time moved on from Edison’s design, German inventor Emile Berliner patented his version of the phonograph that instead used flat discs. As this style of record was simpler to produce and store, it became the dominant format. During the first half of the 20th century, most records where made from shellac — a resin derived from the secretion of the lac bug (we know, it’s odd). As time went on, other advancements were made, allowing you to have the thinner high-fidelity vinyl plastic records you have now.
When it comes to reproducing sound, your modern record player does it similarly to the original invention thought up by Edison, but it instead uses electricity and a magnetic cartridge. When you turn your record player on and lower the needle (properly known as a stylus) onto the record surface, it begins to ride in the grooves. Instead of vibrating a diaphragm, however, the stylus vibrates and moves a small magnet in what is known as the cartridge (the part holding the stylus itself). The movement of the magnet creates an electrical signal that is amplified, usually through a powered A/V receiver, and sent to your speakers.
Your speakers are merely large magnets connected to coils, which are connected to a cone. When an electrical signal enters the speakers, it moves the magnet and vibrates the cone. The cone pushes air, creating sound, allowing you to listen to your favorite tunes. Depending on your record player and setup, you may be wondering how a record produces two different sounds in two separate speakers for a stereo effect — let’s talk about that.
Stereo, two for one: Two-channel audio
Your record player can produce stereo music due to the way the grooves in your record have been cut. When Edison released the cylinder phonograph, its grooves moved up and down over what was known as hills and valleys. Berliner’s flat discs, however, opted to record music with the needle vibrating left and right (side to side) in a v-shaped groove. When the middle of the 20th century rolled around, and record companies wanted to record two tracks at once — one in the left channel and one in the right — they opted for a bit of a hybrid design.
Record companies decided to cut the grooves at a 45-degree angle. This means that as the stylus rides through the grooves, the right side of the wall contains one track, and the left side of the wall comprises another. Your record cartridge can move in conjunction with these 45-degree angles, ensuring the right magnet movement gets sent to the correct left or right speaker. We know, it’s a bit complex, but perhaps the old video from RCA included above will help explain the miracle of stereo.
Speeds and numbers: A few details
You now know the basics of how a record player works. But what about all the numbers you hear about? What is a 45 record, and how is it different than an LP? For that matter, what’s an LP?
With modern record players, you may notice a speed selector with numbers such as 33 1/3, 45, and 78. This just corresponds to the speed, measured in rpms, that your chosen record must spin at when being played. The 78 rpm option is a left over from the days of shellac records, which were played at higher speeds. The 33 1/3 and 45 rpm options, however, are the two speeds that most modern records tend to be offered; the result of a format war between RCA and Columbia in the 1940s. All you need to know is that you should check your record for the correct speed before playing it. You won’t damage the record by selecting the wrong speed, but it will sound either super sped up or slowed way down.
When it comes to the LP, that is simply the name that Columbia chose to call its 12-inch records, playing at 33 1/3 rpm. LP stands for “Long Playing” and was meant to signify newer records that could play for over 20 minutes, compared to the shellac record’s much shorter playing time of fewer than four minutes. Now that you know how a record player works, go listen and enjoy!