According to the structure of the box, professional audio can be divided into sealed speakers, inverted speakers, labyrinth speakers, sonic tube speakers and multi-cavity resonant speakers. Among them, the most used in professional speakers is the inverted speaker, which is characterized by wide frequency response, high efficiency, high sound pressure, and conforms to the professional audio system speaker type, but because of its low efficiency, it is less in professional speakers. Applications, mainly for home speakers, only a few monitor speakers use a closed box structure. The sealed speaker has the advantages of simple debugging, wide frequency response and good low frequency transient characteristics, but the requirements for the phono unit are high. At present, among the various types of speakers, the inverted speaker and the sealed speaker occupy most of the proportions, and other types of speakers have many structural forms, but the proportion is small.
1. Closed Enclosure is the simplest speaker system. The 1923 is proposed by FrederICk and is composed of a speaker unit mounted in a fully sealed box. It can completely isolate the forward radiated sound waves and the backward radiated sound waves of the speaker. However, due to the existence of the closed box, the resonance quality of the speaker is increased to generate resonance, and the lowest resonant frequency of the speaker is increased. The sound of the closed speaker is a bit deep, but the bass analysis is good. When using a normal hard-loop speaker, in order to obtain a satisfactory bass playback, a large-sized large-sized cabinet is required. Most of the new closed-type speakers are selected with a high Q value. Unisex speaker. By utilizing the elastic effect of the compressed air mass enclosed in the box, although the speaker is installed in a small box, the air cushion behind the cone will exert a counter-dynamic force on the cone, so the small closed type speaker is also called an air cushion type speaker. .
2, Bass-Reflex Enclosure ( also known as AcoustICalPhaseInverter), invented by Thuras in 1930. In its load, there is a sound outlet opening on one of the panels of the cabinet. There are various positions and shapes of the openings, but most of them also have a sound conduit in the hole. The relationship between the inner volume of the cabinet and the sound conduit hole, according to the principle of resonance, produces resonance at a specific frequency, which is called the anti-resonance frequency. The sound wave radiated by the backward radiation of the speaker is inverted by the duct, radiated to the front by the sound outlet, and is integrated with the forward radiated sound wave of the speaker, which can provide a wider bandwidth than the closed type, and has higher sensitivity and smaller 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 speaker can reproduce rich bass with a small box, which is the most widely used type.
3, the acoustic resistance speaker (AcoustICresistanceEnclosure) is essentially a deformation of an inverted speaker, which is filled with sound absorbing material or structure in the sound outlet conduit, as a semi-closed box to control the phase inversion, so that it is buffered, Reduce the anti-resonance frequency to widen the bass playback band.
4. The transmission line type speaker (LabyrinthEnclosure) is named after the classical electric theory transmission line. The sound tube made of sound-absorbing wall board is provided behind the speaker, and its length is 1/4 or 1 of the wavelength of the desired low-frequency sound. 8. Theoretically it attenuates the sound waves coming from behind the cone, preventing it from reflecting to the open end and affecting the acoustic radiation of the woofer, but in fact the transmission line speaker has a slight damping and tuning effect, increasing the speaker near or below the resonance frequency. Acoustic output and reduce the amount of stroke while enhancing the bass output. Usually, the sound tubes of such speakers are mostly labyrinth-like, so they are also called labyrinth or labyrinth.
5. Passive radiant speaker (DroneConeEnclosure) is a branch of bass reflex speaker, also known as empty paper cone speaker. It was published by Olson and Preston in the United States in 1954. Its opening sound port is made up of a non-magnetic circuit. Replace with the empty cone of the voice coil (passive cone), the radiation generated by the vibration of the passive cone and the forward radiation of the speaker are in the same phase, and the composite sound is formed by the air in the box and the support of the passive cone. The mass of the passive cone forms resonance and enhances the bass. The main advantage of this kind of speaker is that it avoids the unstable sound generated by the sound hole, and can obtain good sound radiation effect even if the volume is not large, so the sensitivity is high, and the working vibration of the speaker can be effectively reduced. Small, the sound is clear and transparent.
6. Coupling cavity speaker is a box structure between closed and bass reflex type. It was published by HenryLang in the United States in 1953. Its output is output from the sound hole driven by one side of the cone, and the other side of the cone. Then coupled with a closed box. The advantage of this kind of speaker is that the amount of air pushed by the speaker is greatly increased at low frequency. Since the coupling cavity is a tuning system, when the movement of the cone is restricted, the output of the sound outlet does not exceed the sound output of the single cone, and the low frequency is widened. The range is reduced, so the distortion is reduced and the power is increased. The A.S.W (AcoustIC SuperWoofer) speaker released by Kojima Koji of Lo-d in Japan in 1969 is a coupled-cavity speaker suitable for reproducing bass with a small-caliber long-stroke speaker without distortion.
7. Horn type Enclosure For the household type, it is mostly in the form of a folded horn (FoldedHorn). Its horn bell is coupled to a large air load at the mouth, and the drive end has a small diameter. It is fully sealed and the pressure inside the chamber is mostly on the back of the speaker cone. In order to maintain the balance of the pressure before and after the cone, the inverted horn is placed in front of the speaker. The folding horn speaker is a derivative of the inverted speaker, and its sound effect is better than that of the general bass reflex speaker of the closed speaker.
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