Quick Check: these different systems of sound transduction exist
Electrodynamic:
This principle is the most common today, because it is inexpensive and has a very high playback quality.
A coil fed by the audio signal moves in the magnetic field of a permanent magnet, transmits this movement to a membrane and thus converts voltage into sound.
Example: Apple AirPods Pro
Electrostatic:
This principle works like an inverted condenser microphone:
An extremely thin and current-conducting polyester membrane is supplied with a bias voltage and is clamped between two perforated metal plates. This design requires a high voltage (100 volts to 1,000 volts) for the diaphragm to vibrate effectively. However, because the diaphragm is only a few microns thick, headphones with this design have a wider frequency range. Some high-end headphones have this technology, but it is costly to manufacture and thus makes them expensive.
Balanced Armature:
Balanced Armature (BA) literally describes how the transducer works.
Here, a small movable armature sits exactly in the center of a magnetic field. If current now flows through the coil around the armature, it becomes magnetized and can easily move in the magnetic field between the permanent magnets. Since the armature is connected to the diaphragm, sound is generated in this way. From the resting position of the armature in the center of the magnetic field, in which no force acts on it and the diaphragm, comes the name “balanced”. A great advantage of this design is that it can produce sound from little current, furthermore BA drivers are small and light and more precise and faster in reproduction than dynamic drivers. Today, this design is used in in-ear headphones and hearing aids because of its small size and good sound characteristics, but mainly in higher price segments, because BA drivers are more expensive than a dynamic.
Example: Ultimate Ears UE 18+ Pro
Isodynamic/orthodynamic/magnetostat:
Increasingly used in current headphone production, but due to function, heavy magnets must be installed.
This adds a lot of weight and can reduce wearing comfort. In simple terms, the diaphragm is stimulated to oscillate between two permanent magnets by a low-frequency voltage applied to an external helical coil.
Example: Edifier Stax Spirit S3
Electromagnetic:
These transducers are no longer manufactured today because they have very poor reproduction quality.
Here an iron diaphragm is moved, which radiates the sound directly. Current runs through two premagnetized coils, their magnetic poles are located close behind the membrane.
