But why use the speakers instead of directly to the speaker to listen to the sound?

We know that the speaker's vocal components are speakers, but why use the speakers, rather than directly take the speaker to listen to?
Speakers of the reason of the existence of the box to, mainly in order to prevent the front side and the back side of the loudspeaker diaphragm acoustic signal directly to form a loop, resulting in only small wavelength of high frequency sound can spread out, and other voice signal is superimposed offset.
The physical model of the speaker is in a infinite rigid baffle open a hole, install speakers, so that we can ensure the front side and the back side of the speaker's voice signal does not form a loop, caused by sonic loop.
But in actual use, the speaker is not possible to make infinite. Therefore, people behind the speaker baffle formation a confined space, and ensure the sonic positive transmission.
Attendant problems: speaker closed after due to atmospheric pressure, the speaker box is bigger is conducive to low frequency sound reduction, so the volume of the sound box is according to a woofer speaker sizes calculated data as a compromise.
A lot of ambient is not allowed to have too big box, people in order to further reduce the volume and according to the acoustic characteristics and strengthen the requirements of low frequency sound reproducing the box cataract panel is designed, inverted tube, resonance cavity, mainly to the voice signal to certain wavelengths increase in the low frequency band to and further reduce the atmospheric pressure influence on the reduction of sound.
The speaker is one of the weakest parts in the audio equipment, and for the acoustic effect, it is one of the most important parts.. Magnetic circuit and speaker has various classification: according to the transducer can be divided into electric, electromagnetic, piezoelectric, digital and other; according to the vibration membrane structure can be divided into single paper pots, composite paper pots, compound horn, coaxial and other; according to the diaphragm at the beginning can be divided into cone, dome type, flat type, belt type and so on many kinds of; according to the playback frequency can be divided into high frequency, intermediate frequency and low frequency, ultra low frequency band speakers. According to the magnetic circuit forms can be divided into external magnet, magnetic type, double magnetic circuit and shielding type variety; by nature can be divided into ferrite magnet, NdFeB magnet, aluminum nickel cobalt magnetic speaker. According to the vibration membrane materials can be divided into paper and non paper cone loudspeaker. The A and the electric speaker are the most widely used, which make the vibrating film vibrate and sound by the interaction between the sound circle and the constant magnetic field.. Electric bass loudspeaker cone type is in the majority, mediant loudspeaker for cone or dome type, tweeter is with the ball and belt, horn type is commonly used.
The structure of B and cone basin is simple, and the energy conversion efficiency is high.. It uses the vibrating film material to pulp materials, or the incorporation of wool, silk, carbon fiber and other materials, in order to increase its rigidity, internal damping and waterproof performance and so on. A new generation of electric cone loudspeaker using the non paper diaphragm material, such as polypropylene, mica polypropylene carbide, carbon fiber textile, plates cloth, hard aluminum foil, CD corrugated, glass fiber composite materials, performance progress raise.
The top speaker C, soft and hard sphere ball ball top points. Soft ball on the loudspeaker vibration film color silk, silk, phenolic resin impregnated cotton, chemical fiber and composite materials, its characteristics is beautiful sound playback; hard sphere top speaker diaphragm color aluminum alloy, titanium alloys and beryllium alloy materials and its characteristics is reproducing crisp sound quality.
D, horn loudspeaker radiation and cone type speaker is different, which is in the vibration of the vibrating diaphragm, sound after the horn again diffused out. Its characteristic is high, and the radiation efficiency of the electro acoustic conversion distance, small distortion, but the reproduction band and narrow directivity.
E, the voice coil of the loudspeaker directly fabricated in the entire film (aluminum alloy film, etc.), the sound circle and the vibration film directly coupled. The alternating magnetic field produced by the voice coil interacts with the constant magnetic field, so that the vibration of the belt vibrating film is radiated by the sound wave.. Its characteristic is fast response speed, distortion is small, playback quality is exquisite, level is good.
The sound box is used to eliminate the short circuit of the speaker unit, suppress the acoustic resonance, broaden the frequency range, reducing distortion. The box body of the box has the bookshelf type and the floor type, and the vertical and the horizontal type. Inside structure of the box body and sealed, the phase inverted type, band-pass, empty paper basin type, labyrinth, symmetric drive type and horn type etc. various forms, the most commonly used is closed, the phase inverted type and formula.
Landing sound box is a large box, box height above 750mm, the bookshelf loudspeaker box height below the 750mm, medium-sized Bookshelf Speakers between 450MM~750MM, 450mm below for small bookshelf speakers.
Home theater system lead the box for vertical speakers, bookshelf, but also use a floor type, which according to the audio-visual room size, power amplifier power size and personal hobby. Usually, the audio-visual room in 15 square meters below, should choose medium-sized Bookshelf Speakers; less than 10 square meters shall be used in the small bookshelf box; more than 15 square meters room, can choose medium-sized Bookshelf Speakers or landing box. Front main speakers, speakers and surround speakers were to design a phase inverted type is in the majority, the second is closed and 1 / 4 wave loading type, labyrinth type. The subwoofer with the formula and double chamber double opening type mostly, followed by inverted, closed.
The division of power divider and electronic frequency divider is the main function of the frequency band segmentation, amplitude frequency characteristic and phase frequency characteristic, impedance compensation and attenuation.