How things work
How a record plays music
A working turntable, with the groove and the cartridge enlarged beside it. The stylus, the magnet and the signal are all worked out from the shape of the groove, so change the groove and everything follows.
The record player
Look at
Cut your own groove
Which channel carries the tone
What is simplified
- The close-up is not to scale with itself. A real groove is about 0.05 mm wide, far too small to see next to a cartridge that is nearly 2 cm across, so the groove, the stylus tip and the cantilever are drawn many times too large. The wiggles are also drawn bigger than a real tone would cut them.
- The close-up runs about 300 times slower than life. At real speed a 440 Hz tone moves the stylus 440 times a second.
- The record here holds one steady tone that you set. Music is the same thing with a far more complicated wiggle. The sound button plays that tone from the model's own output; nothing on this page is a recording.
- The spiral moves the arm inward by about a tenth of a millimeter each turn. The model does that at true scale, so you will not see it unless you let it play for a while.
- Cartridge makers arrange the magnet, pole pieces and coils in different ways. This one shows the principle: a magnet on the cantilever, and one pair of coils for each slant. The body is cut in half; the parts inside are left whole.
- Real records are cut with the bass turned down and the treble turned up, and the amplifier reverses that. It is left out here.
In short
A record stores sound as a wavy groove spiralling across the disc. A motor turns the platter so the groove passes under a stylus, the needle, which rides in it and wiggles as the shape changes. The tonearm holds the stylus and cartridge in place. In the cartridge, the movement is converted into a tiny electrical signal, in many designs using a magnet and coils. An amplifier makes that signal stronger, and speakers turn it into sound.