How many do you know about the structure of commonly used speaker boxes?

According to the sounding principle of speakers, speakers can be divided into many types. Similarly, according to the different structures inside the cabinet, the speakers can also be divided into many types, such as sealed speakers, inverted speakers, labyrinth speakers, sonic tube speakers, and multi-cavity resonant speakers. Some are suitable for professional speakers, and some are suitable for home speakers, each with its own characteristics. Next, "A New Life of Audio and Video" will come to you in detail.

Inverted speakers are more commonly used in speakers, which are characterized by wide frequency response, high efficiency, and large sound pressure, which are in line with the type of professional audio system speakers. However, due to their low efficiency, they are rarely used in professional speakers. Mainly used for home speakers. Sealed speakers have the advantages of simple design and manufacture, wide frequency response, and good low-frequency transient characteristics. However, the requirements for speaker units are higher, and some monitor speakers adopt a closed box structure.

At present, in all kinds of speakers, inverted speakers and sealed speakers account for the majority of the proportions. Other types of speakers have many structural forms, but they account for a small proportion.

△Closed speaker
It is the simplest speaker system. It was proposed by FrederI Ck in 1923. Simply put, the speaker unit is installed in a fully sealed box. It can completely isolate the forward and backward radiated sound waves of the loudspeaker, but due to the existence of the closed box, the rigidity of the loudspeaker's motion mass to produce resonance is increased, and the lowest resonant frequency of the loudspeaker is increased.
The sound of the enclosed speakers is a bit deep, but the bass analysis is good. When using ordinary hard folding ring speakers, in order to obtain satisfactory bass reproduction, a large cabinet with a large volume is required. Most of the new enclosed speakers use a suitably high Q value. Compliant speakers. Utilizing the elastic effect of the compressed air quality enclosed in the box, although the speaker is installed in a smaller box, the air cushion behind the cone will exert a reaction force on the cone, so this small enclosed speaker is also called an air-cushioned speaker .

△Bass reflex speaker (inverted phase speaker)
Bass reflex speakers, also called phase-inverted speakers, were invented by Thuras in 1930. In its load, there is a sound outlet opening on a panel of the box body. There are various opening positions and shapes, but most of the holes are also equipped with sound ducts. The relationship between the internal volume of the box and the sound duct hole, according to the principle of resonance, produces resonance at a certain frequency, which is called the anti-resonance frequency. The sound waves radiated from the loudspeaker in the backward direction are inverted through the tube, and then radiated to the front from the sound outlet, and superimposed in phase with the sound waves radiated in the forward direction of the loudspeaker.
It can provide a wider bandwidth than the closed type, with higher sensitivity and less distortion. Ideally, the lower limit of the low frequency playback frequency can be as much as 20% lower than the speaker resonance frequency. This kind of loudspeaker can reproduce rich bass with a smaller cabinet, and is currently the most widely used type.

△Acoustic resistance speaker
It is essentially a deformation of a phase-inverted speaker, which is filled with sound-absorbing material or structure in the sound outlet duct, which acts as a semi-closed box to control the phase-inversion and buffer it, so as to reduce the anti-resonance frequency and broaden the bass replay. Frequency band.

△Transmission line speaker
It is named after the transmission line of classical electrical theory. There is a sound tube made of sound-absorbing wall panels on the back of the speaker, and its length is 1/4 or 1/8 of the wavelength of the low-frequency sound that needs to be boosted.
Theoretically, it attenuates the sound waves coming from the back of the cone, preventing it from being reflected to the open end and affecting the sound radiation of the woofer. However, in fact, the transmission line speaker has a slight damping and tuning effect, which increases the speaker near or below the resonance frequency. Acoustic output, and increase the bass output while reducing the amount of stroke. Usually the sound ducts of this kind of sound box are stacked in a labyrinth shape, so they are also called labyrinth or tortuous.

△Passive radiating speaker
It is a branch of the bass reflex speaker, also known as the empty cone speaker. It was published by Olson and Preston in the United States in 1954. Its opening sound outlet consists of an empty paper cone (passive cone without magnetic circuit and voice coil). ) Instead, the radiation generated by the passive cone vibration and the forward radiated sound of the speaker are in the same phase working state, and the composite sound and passive cone quality formed by the air in the box and the passive cone support component are used to form resonance to enhance the bass.
The main advantage of this kind of speaker is to avoid the unstable sound produced by the sound hole reflected, and it can get a good sound radiation effect even if the volume is not large, so the sensitivity is high, and it can effectively reduce the speaker's working amplitude and the influence of standing waves. Small, the sound is clear and transparent.

△Coupling cavity speaker
It is a box structure between the closed type and the bass reflex type. It was published by Henry Lang in the United States in 1953. Its output is output by the sound hole driven by one side of the cone, and the other side of the cone is connected to a closed box. coupling.
The advantage of this kind of speaker is that the amount of air pushed by the speaker at low frequencies is greatly increased. Since the coupling cavity is a tuning system, when the cone movement is restricted, the output of the sound outlet does not exceed the sound output of a single cone, which broadens the low frequency weight. Amplify the range, so the distortion is reduced, and the withstand power is increased. In 1969, the A·S·W (AcoustIC SuperWoofer) speaker released by Yukihiko Kawashima of Lo-d, Japan is a coupled cavity speaker, suitable for reproducing bass without distortion with small-diameter long-stroke speakers.

Nano-coupling cavity complete speaker

△ trumpet speaker
For the household type, the folded horn is mostly used. The horn of the horn is coupled with a larger air load at the mouth, and the diameter of the driving end is small. The back of this type of speaker is fully sealed, and the pressure in the chamber is large. On the back of the speaker cone.
In order to keep the pressure balance between the front and rear of the cone, an inverted horn is installed in front of the speaker. The folding horn speaker is a derivative of the inverted speaker, and its sound effect is better than the general bass reflex speaker of the closed speaker.
Of course, no matter what kind of cabinet structure the speaker adopts, it is fundamentally inseparable from the acoustic design of the cabinet. At the same time, speakers with different cabinet structures have their own unique sound effects, which are suitable for different occasions, and there is no absolute strong and weak.
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