Reflex Enclosure：

It is the most popular design. When the diaphragm of the speaker generates sound, the sound waves which are reflexed from the rear board will be sent out by the reflex pipes. The size and length of the reflex holes and pipes all affect the extension of low frequency, therefore according to the character of the speaker, we should design proper holes and pipes in order to get the best speed and the extension of low frequency.

Closed Enclosure：

The enclosure is entirely sealed. This design will decrease the operating efficiency even though the low frequent voice is good. Therefore in order to get better control, we must give high power to operate it or the speed of the low frequency will be delayed.

Passive Radiator Enclosure：

A kind of closed enclosure, mainly adds another low frequent speaker. When it vibrates to generate sound, the passive radiator diaphragm is pushed by air. The disadvantage is low efficiency and speed.

Isobaric Type Enclosure：

It is able to increase the low frequent energy, but the closed design causes the low efficiency. When the two speakers work at the same time, if the sound is out of phase, it affects the results as well.

Transmission Line Enclosure：

The transmission line enclosure extends the low frequency by a long wave guide; however the over-length of the wave guide may lower the speed of the low frequency.

The enclosures we introduced above can not be completely applied in all the electronic products, it is for consultation; we need to face and solve more problems in reality.