Vibration of dynamic drivers (Part 2)

The topic of “vibrations” produced by dynamic drivers. Part 2.

The materials of earphone housings, such as metal, resin, and wood, have different vibration attenuation rates.

Soft woods and resins have a high vibration attenuation rate, while materials such as aluminum have a low vibration attenuation rate.

However, many materials with lower vibration damping rates, which do not reduce vibrations as much, are more suitable acoustically because of the faster speed of sound propagation.

The front housing of an earphone (the housing in front of the driver) must suppress the vibration of the dynamic driver because the driver is mounted, yet sound (vibration) must travel fast without attenuation.

In other words, two contradictory things are required.

So what if the part where the dynamic driver is mounted and the cup and nozzle part in front of the driver are made of different materials?

In the case of normal earphones, the front housing is often a single piece.

However, if the nozzle or cup and the driver mounting area are separated, a combination design is required to join the two.

The front housing with interchangeable nozzles has a screw structure, but in order to make this screw structure, the thickness of the housing must be greater than the height of the screw bumps.

In other words, the front enclosure must be larger or thicker.

However, this in turn limits the thickness of the enclosure and the placement of the drivers.

For example, the nozzle of 634ears earphones is 0.5mm thick. To make a screw structure within this 0.5mm, the thickness would have to be at least 1mm.

This would make it difficult to control the sound because the specific gravity of some metal materials would be too high, resulting in a sound that is too strong and sharp.

In addition, the nozzle part may be subjected to large force when removing an earpiece that is too small for the diameter of the nozzle, and may break. Therefore, it is definitely safer to use a one-piece construction in terms of strength.

For these reasons, at this point in time, 634ears does not use vibration suppression by the material itself, but uses a composite method of vibration suppression by incorporating another vibration suppression in the way the driver is mounted.