How does a Record Player work?
Technology is always advancing, even though the average person’s understanding of it may not be able to keep up to speed. New gadgets are incredibly complex to understand, yet even older technologies can be puzzling—like an old record player, for example. How exactly do record players work? That’s a question that has puzzled a lot of people for many, many years, even though record player (or phonograph or gramophone) technology remained largely the same for over a century.
Record players were first created in the 1870s, with the first patent for this kind of technology being granted to Thomas Edison, though it appears from the historical records that a few other inventors in other parts of the world developed similar theories and devices, all independently of each other. Though incredibly rudimentary, the theories put in practice by Edison’s first phonographs were the same ones that continued to serve as the basis for ordinary record players, and furthermore are the same basic concepts utilized for creating compact discs (which replaced the record player as the dominant music recording medium by the 1980s).
Understanding the theory behind it all is necessary before one can acquire a nuanced understanding of the actual parts of the hardware. What Edison and other brilliant scientists and inventors of his age realized was that sound is essentially vibration: any given sound is composed of vibrations at determined frequencies, which create sound waves. These rather astute people figured out that it was possible to leave a series of marks on a surface that, when passed over with another object, would cause said object to vibrate in a predictable fashion; those vibrations could be turned into an electrical current, and that current could then be amplified and played back through speakers, so as to create audible noise. All of that simply from a series of ridges and gullies on a surface!
The first record players actually used tin cylinders rather than vinyl discs—these did not appear on the scene for several decades after the first audio playback devices. By embossing a series of bumps within a continuous groove that wound around the cylinder from one end to the other, Edison figured out that he could place a hollow needle over the groove and rotate the cylinder to read the impressions. The particular physical marks in a given section of the groove would cause the needle to move in a certain way, and that movement could be picked up by an electromagnetic cartridge and converted into an electric current. What is necessary is that the “wiggling” of the needle (caused by the marks in the groove) correspond proportionally to the dimensions of the sound wave needing to be reproduced.
The change from the tin cylinders used in Edison’s original design to the flat vinyl discs we are so familiar with came in the early 1900s, and had to do with the fact that it was more practical to turn a flat disc with a spiral groove that begins at the outer rim of a disc and ends near its center.
The needle used to read the marks within the grooves is referred to as the stylus. The most common and inexpensive styluses are made of sapphire, though there are crystal and diamond styluses that have been included in certain record players. The stylus is connected to a small but crucial component made out of ceramic piezoelectric material, which is responsible for switching the detected motions into small electrical voltage. The reason the stylus is able to so effectively detect the exact sounds that were recorded is because the tip of the stylus is so sharp and fine that a lot of pressure exists on the point of contact between the needle and the vinyl disc, making the stylus very sensitive to precisely what has been embossed in the medium. Given this vast pressure at the point of contact, styluses suffer considerable wear and tear, and even the hardest materials (aka diamond) need to be replaced occasionally; furthermore, the discs themselves suffer scratches from this contact, a problem which was totally avoided with the invention of laser readers instead of styluses used in record players.
When the stylus is moved, the electromagnetic coil it is connected to experiences fluctuations in the magnetic field being generated, and these fluctuations induce an electric charge in the coil. When amplified, these charges are roughly (sometimes more, sometimes less) loyal reproductions of the original sound that was recorded.
When it comes to creating the vinyl discs themselves, things basically go into reverse mode: an album cutter (a high-precision automatic device) is connected to an input source which indicates to it when a mark needs to be left in a groove. As the cutter begins etching the grooves in a spiral fashion into the blank disc, it raises or lowers the tip of the cutter and swivels it from side to side ever so slightly to leave unique marks corresponding to the sound waves of the original recording. Of course, the cutter needs to be extra careful not to “cut across” from one groove to another, something which would create problems for the stylus trying to read the marks, as it would leap from one moment of a recording to another, disparate moment. Significant bass frequencies had to be minimized for the album cutting process (and subsequently compensated during amplification, to preserve original sound quality), as the width of the sound wave caused exactly this sort of “cut across” to happen.
To get a better, more tangible understanding of how record players work, there is a simple experiment used often with school children as an early lesson in physics. All you will need is an old vinyl disc that you don’t mind scratching up a bit (not a collector’s item!), a small piece of paper (roughly 3 square inches) and a small cocktail stick. Drive the cocktail stick through the piece of paper, in such a way as to create a miniature sail and mast, with the stick passing through the paper in two spots. Then, without pressing down too hard, pass the stick over a groove in the vinyl at a steady speed—you should be able to hear a faint noise! The paper serves as a slight amplifier, and you can understand how with a power source, this noise could be amplified enough to be heard at normal listening levels.
as the dominant music recording medium by the 1980s).
Understanding the theory behind it all is necessary before one can acquire a nuanced understanding of the actual parts of the hardware. What Edison and other brilliant scientists and inventors of his age realized was that sound is essentially vibration: any given sound is composed of vibrations at determined frequencies, which create sound waves. These rather astute people figured out that it was possible to leave a series of marks on a surface that, when passed over with another object, would cause said object to vibrate in a predictable fashion; those vibrations could be turned into an electrical current, and that current could then be amplified and played back through speakers, so as to create audible noise. All of that simply from a series of ridges and gullies on a surface!
The first record players actually used tin cylinders rather than vinyl discs—these did not appear on the scene for several decades after the first audio playback devices. By embossing a series of bumps within a continuous groove that wound around the cylinder from one end to the other, Edison figured out that he could place a hollow needle over the groove and rotate the cylinder to read the impressions. The particular physical marks in a given section of the groove would cause the needle to move in a certain way, and that movement could be picked up by an electromagnetic cartridge and converted into an electric current. What is necessary is that the “wiggling” of the needle (caused by the marks in the groove) correspond proportionally to the dimensions of the sound wave needing to be reproduced.
The change from the tin cylinders used in Edison’s original design to the flat vinyl discs we are so familiar with came in the early 1900s, and had to do with the fact that it was more practical to turn a flat disc with a spiral groove that begins at the outer rim of a disc and ends near its center.
The needle used to read the marks within the grooves is referred to as the stylus. The most common and inexpensive styluses are made of sapphire, though there are crystal and diamond styluses that have been included in certain record players. The stylus is connected to a small but crucial component made out of ceramic piezoelectric material, which is responsible for switching the detected motions into small electrical voltage. The reason the stylus is able to so effectively detect the exact sounds that were recorded is because the tip of the stylus is so sharp and fine that a lot of pressure exists on the point of contact between the needle and the vinyl disc, making the stylus very sensitive to precisely what has been embossed in the medium. Given this vast pressure at the point of contact, styluses suffer considerable wear and tear, and even the hardest materials (aka diamond) need to be replaced occasionally; furthermore, the discs themselves suffer scratches from this contact, a problem which was totally avoided with the invention of laser readers instead of styluses used in record players.
When the stylus is moved, the electromagnetic coil it is connected to experiences fluctuations in the magnetic field being generated, and these fluctuations induce an electric charge in the coil. When amplified, these charges are roughly (sometimes more, sometimes less) loyal reproductions of the original sound that was recorded.
When it comes to creating the vinyl discs themselves, things basically go into reverse mode: an album cutter (a high-precision automatic device) is connected to an input source which indicates to it when a mark needs to be left in a groove. As the cutter begins etching the grooves in a spiral fashion into the blank disc, it raises or lowers the tip of the cutter and swivels it from side to side ever so slightly to leave unique marks corresponding to the sound waves of the original recording. Of course, the cutter needs to be extra careful not to “cut across” from one groove to another, something which would create problems for the stylus trying to read the marks, as it would leap from one moment of a recording to another, disparate moment. Significant bass frequencies had to be minimized for the album cutting process (and subsequently compensated during amplification, to preserve original sound quality), as the width of the sound wave caused exactly this sort of “cut across” to happen.
To get a better, more tangible understanding of how record players work, there is a simple experiment used often with school children as an early lesson in physics. All you will need is an old vinyl disc that you don’t mind scratching up a bit (not a collector’s item!), a small piece of paper (roughly 3 square inches) and a small cocktail stick. Drive the cocktail stick through the piece of paper, in such a way as to create a miniature sail and mast, with the stick passing through the paper in two spots. Then, without pressing down too hard, pass the stick over a groove in the vinyl at a steady speed—you should be able to hear a faint noise! The paper serves as a slight amplifier, and you can understand how with a power source, this noise could be amplified enough to be heard at normal listening levels.
Tags: music technology | music technology | amplification | amplification | music | music | vinyl