One of my daily driver Audio Technica wired headphones was acting up. Opened it up and it was a simple fix. Nothing much to write home about. Found a loose wire which was fixed by adding a bit more solder and reattaching it. Works well now. The Internals of any wired headphones are mostly the same. They contain a driver/speaker on both ear lobes and are driven via extremely thin wires. The diameter of the driver here is 36mm. Nothing too fancy.
Now how do headphones actually work? The headphone dynamic driver consists of three major parts: A permanent magnet, a voice coil(electromagnet) and a diaphragm. When an audio signal(electric waveform) is fed into the voice coil, it gets attracted/repelled by the static magnetic field. These coils are usually glued onto a thin diaphragm which moves back and forth to displace the air. This creates the sound you hear from the headphones. This concept of a driver hasn’t changed in over 100 years. In the olden days, they used to have metallic diaphragms(Different from the plastic ones we have now) and strong electromagnets driven by the signal. The thicker diaphragms will need more power to move but the basic principle remains the same.
Headphones can have driver sizes from 20mm – 50mm. The driver sizes just mention the diameter of the static magnet. Marketing folks of companies have a field day trying to make you believe that the bigger driver diameter means better headphones. That’s not the case(Think earphones. They have driver sizes of 8mm-10mm). Bigger drivers mean that it can potentially displace more air. ie) It can produce more sound or can be louder. This doesn’t necessarily translate to an overall better quality sound. The sound quality of headphones is determined by the driver along with with the diaphragm quality and even the padding used in the headphones. It’s an overall system property. All of these determine the range of sound frequencies your headphone can faithfully reproduce in your ear.