Since the nineteenth century after Thomas Edison invented the phonograph, mankind has entered the new era of audio replay. As a mouthpiece of the replay music, sound box for nearly a century the evolution of the development process, gradually formed the now closed, inverter type two big mainstream and labyrinth, horn type, such as passive radiant tributary polymorphism of coexisting situation.

Concept in the modern sense of closed box first appeared in 1944 in h. f. Olson and j. Preston in the United States patent, due to the vibration speakers, the sound waves before and after the phase contrast, the impermeability of box body is caused by the diaphragm vibration caused by strong mechanical wave to push the air in the cabinet repeatedly compression and expansion, therefore require the box body solid careful, in case of leaking sound waves. Closed box is the craft simple, the advantages of instant response is good, suitable for small book posture and hanging speakers, its shortcomings, first of all, is a waste of the 50% of the sound energy; Second, because behind the speaker formed air "spring", so the system resonance frequency increases, the low frequency response of variation; And because the closed box heavy sound damping materials and use rubber edge more speaker system and cause the sensitivity of the system as a whole than other forms of speakers reduced 3-8 db.

Inverter type sound box is also called open box, first by a. l. Thuras described in the patent in 1932. Thereafter because a. n. Thieke and r. h. Small played A key role to the development, thus "Thieke/Small" often become the pronoun of inverted box. Depending on the inverter hole position before and after, and can be divided into two inverter is cast and display box, no difference between the two basic on the function. Followed the principle is that the speaker vibration mechanical wave after airway inverting the vibration and sound basin similar function, thus greatly improving the low frequency radiation intensity, extends the low frequency replay the lower limit of frequency. Besides, it reduces the nonlinear distortion. Compared with closed box, when close to the speaker resonant frequency inverter box can improve the speaker cone prominent deformation, thus improve the power output and compression intermodulation distortion; And in theory, also higher than the same volume of closed box 3 db power. But inverted box also is not perfect, the sound box below the resonant frequency of radiation sound pressure of low frequency attenuation fast, easy to produce low frequency "bang" sound, and wind noise, the instantaneous response is inferior to the closed box; Combined with the speaker parameters inconsistent problems and speakers quite sensitive, so complex design, debugging difficult. But with the rapid development of computer technology and the emergence of a variety of CAD software, inverted box production difficulty is reduced, which is currently widely used in high power and high efficiency.

As for the horn type sound box, because of its huge size and promotion; And labyrinth speakers due to its for waves of certain frequencies increase, some frequency band is weaken, the characteristics of the limited to special applications. In comparison, the passive radiant speakers. Passive radiation boxes and empty paper cone speaker, invented by americans, Harry Olson, 1935, has been used today. It is virtually inverting evolution and variety of the enclosure. Its working principle is that when the active radiator (i.e., large caliber bass unit) vibration, air in the box body after inverter on the empty paper cone, promote its vibration, thus doubling the efficiency of low frequency replay. And the convex spherical paper cone can be more evenly replay at low frequency. Compared with ordinary inverting tube, the passive radiator eliminates the standing wave in the cabinet, can improve the sensitivity of low frequency band (that is, the sound pressure level), effectively avoid the harmonic vibration and wind noise. But because of the high technical requirements, so the less passive radiation box in the world. According to the author knows, only the British super sweet, mighty Britain, Sweden, Switzerland and Denmark Wu Shi adopted the technology, etc.