What types of sound transducers are there?

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What types of sound transducers are there?

There are different systems of sound conversion in headphones:

Electrodynamic:
This principle is the most common today because it is cheap and has a very high quality of reproduction.
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.

Electrostatic:
This principle works like a condenser microphone operated in reverse:
An extremely thin and electrically conductive polyester membrane is supplied with a pre-tension and is clamped between two perforated metal plates. This design requires high voltage (100 volts to 1,000 volts) for the diaphragm to oscillate effectively. However, since the membrane is only a few micrometers thick, headphones with this design have a larger frequency range. Some high-end headphones have this technology, but it’s laborious to manufacture and that makes them expensive.

Balanced Armature Transducers:
Balanced Armature (BA) literally means “balanced armature” and describes how the sound transducer works. Here, a small moving armature sits right in the middle of a magnetic field. If current 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 membrane, sound is generated. The term “balanced” comes from the resting position of the armature in the center of the magnetic field, in which no force acts on it and the membrane. A big advantage of this design is that it can produce sound from little power, furthermore BA drivers are small and light and more precise and faster in playback than dynamic drivers.

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Is little used in current headphone production, as heavy magnets have to be installed for functional reasons. This makes for a high weight and can reduce the wearing comfort. To put it simply, the membrane is excited to oscillate between two permanent magnets by the low-frequency voltage supplied via a coil that is applied outwards in a spiral shape.

Electromagnetic:
These converters are no longer manufactured today because they have a very poor reproduction quality. Here an iron membrane is moved, which emits the sound directly. Current runs through two pre-magnetized coils whose magnetic poles are located just behind the membrane.

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