The frequency divider, a box body and structure types
Another important component of frequency divider is also sound box, its main duty is to turn the sound signal is divided into a plurality of different frequency signal and then assigned to each corresponding speaker unit. At the same time, can also play between phase correction unit and the unit difference and sensitivity to inconsistent problem. Therefore, the frequency divider design directly affects the quality of the sound reproduction of sound box.
At present, the power frequency (frequency LC network) and the electronic frequency is the most commonly used frequency division. The former is composed by capacitance, inductance filter network, its characteristic is the circuit is simple, the use is more convenient, so now most of the civilian speakers have adopted this approach by dividing. However, this division way is easy to appear the audio valley point, produce crossover distortion, and when to divider "order" number, the line is more complex, the power will be consumed more. In addition, the amplifier needs to work in a state of full frequency distortion, so naturally will aggravate the.
"Using an active sound box power frequency
Electronic frequency divider is used mainly for professional sound reinforcement system and active sound box, located between the preamplifier and post amplifier, the way it works is the first weak signal frequency, frequency after power amplifier using independent amplification, and then drive the loudspeaker unit.
Active sound box ^ using electronic frequency dividing
Advantages of this division method is can greatly reduce the power loss in the case of the attenuation slope do very steep, between unit and unit cohesion more perfect. In addition, because the power amplifier work, not in the whole frequency amplifying condition therefore, for power amplifier output power requirement is reduced accordingly, so the distortion rate can be greatly reduced. However, the line structure of electronic frequency divider ratio power divider is more complex, the cost is also a corresponding increase in.
Box type and its structure
Different body structure and the use of materials will constitute the influence of sound. And to the sound box brand of our common, use of closed type, inverted, labyrinth structure sound the largest proportion. Below on the several common sound box structure were introduced:
Closed box (Closed Enclosure) is the most simple loudspeaker system structure, proposed by Frederick in 1923, by the speaker unit arranged in a fully sealed box body which is formed, it will be the speaker prior to the radiation acoustic wave and backward radiation acoustic completely isolated, but due to the existence of closed box body, increases the speaker movement quality produce the resonance of the rigid, make the lowest resonance frequency of loudspeaker rise. Closed box sound some deep bass, but analysis of force is good, the use of ordinary hard folding ring bass speaker, in order to get satisfaction, the need for a large box volume is large, enclosed sound boxes new using closed elastic effect quality of compressed air in the cabinet, although the speakers in the smaller box, cone behind the basin cushion exerts anti driving force of cone, so the small enclosed sound boxes also called air cushion type sound box.
Satellite box ^ 2.1 multimedia speaker usually adopts sealed
Bass reflex type loudspeaker (Bass-Reflex Enclosure) also known as inverted sound box (Acoustical Phase Inverter), invented by Thuras in 1930, there was a sound outlet hole on the box of a panel in its load, hole position and shape are various, but most in the hole is also arranged with a sound duct. The relationship between the volume in sound box guide hole, according to the Helmholtz resonance principle, produce resonance at a particular frequency, known as the anti resonance frequency. The speaker to the sound waves radiated after transcatheter inverted phase, radiation from a sound outlet to the front speakers, and prior to the acoustic radiation of in-phase stack, it can provide wider than the closed box bandwidth, has higher sensitivity, less distortion, under ideal conditions, the lower limit of low frequency playback frequency than the speaker lower resonant frequency more than 20%. The speaker with small box body can replay a rich bass, is currently the most widely used type.
"Former inverted sound box
Acoustic resistance enclosure (Acoustic resistance Enclosure) is essentially a deformation of a phase inverted type loudspeaker box, it is filled with sound absorption material and structure in the sound outlet conduit, as a semi closed box control phase inversion effect, so that the buffer, in order to reduce the anti resonance frequency to stretch the bass frequencies.
Transmission line type sound box (Labyrinth Enclosure) is named after the classical electric transmission line theory, the sound absorption panels made of catheter useful equipment in speaker behind, its length is required to enhance the low frequency sound wavelength of 1/4 or 1/8. In theory it attenuate acoustic waves by cone behind, to prevent the reflection to the open end and the influence of the subwoofer sound radiation. But the actual transmission line type sound box with mild damping and tuning effects, increase the speaker in the vicinity of the resonance frequency or below the sound output, and in enhancing the subwoofer output at the same time reduce stroke volume. Usually the speaker acoustic duct is mostly folded like a labyrinth, so also known as maze or labyrinth.
Passive radiation type sound box (Drone Cone Enclosure) is a branch of bass reflex type loudspeaker box, also known as the empty paper basin type speakers. In 1954 Olson and Preston America is published, it is opening a sound outlet by an absence of magnetic circuit and a voice coil empty paper basin (passive cone) to replace, sound radiation and speaker passive cone vibration generated prior to the sound radiation are at the same working condition, the resonance formed by the air inside the box and the passive cone support components together constitute the composite sound and passive cone quality, enhance bass. The main advantage of the speaker is to avoid the reflected sound hole has unstable voice, even if the volume is not big but also can get good sound radiation effect, so the sensitivity is high, which can effectively reduce the speaker working range, the standing wave effect is small, clear voice.
"Passive radiation type subwoofer (side as the passive radiator)
Coupled resonator type sound box is a box body structure is closed and bass reflex between 1953, America Henry Lang published, its output by the side of the cone driven out of the sound hole of output, the other side cone with a closed box coupling. Advantages of this sound box as the volume of air driven low frequency loudspeaker is greatly increased, due to the coupling cavity is a tuning system, the cone motion restricted, sound output not exceeding acoustic output single cone, spread the low frequency playback range, so the distortion reduction, bear power increase. In 1969 Japan Lo-D Kawashima Yukihiko published A S W (Acoustic Super Woofer) the speaker is a coupled cavity type sound box, suitable for the small caliber long stroke loudspeaker replay bass without distortion.
Horn type speakers (Horn type Enclosure) of the household type, multi use folded horn (Folded Horn) form, its horn trumpet in the mouth with larger air load coupling, drive end diameter is very small, the sound box is sealed on the back, on the back of the box cavity pressure to the loudspeaker cone on. Keep the balance for the protection of the cone pressure before and after, inverted horn device in front of the speaker. Folded horn sound box is inverted sound box is derived, the sound effect is better than the closed box and general bass reflex enclosure.
In addition to the sound box structure have effect on the sound box body outside, the material is also very important. Because in the eyes of the sound designer, an ideal box can not be affected by the vibration unit, so can eliminate brought box vibration noise pollution. But in fact, this case is not exist, so we can only as far as possible to suppress the vibration. Also the designer in striving to achieve this purpose by all means. The most simple and inexpensive method is to use MDF board or wood to make the box body, and then using reinforced to enhance the strength of the box as appropriate drop bass to dye in the box body. But to one part of advanced speaker manufacturers (such as Wilson Audio, YG Acoustics) is used as the metal material of the box body, and some more "Metamorphosis" manufacturers also use marble clamp making box.
* metal material (aluminum) case
But the use of metal or marble made of both the process and the cost are better than those of MDF plate and wood much higher. At the same time, most of the people are always not used to listen to the bass to dye sound, this is because they believe the amount of noise pollution makes the sound more pleasant and more humane. After the above introduction, believe that readers should be on the market mainstream sound box has a certain understanding. But in fact, there are a lot of box type, rely on just a few pages of the narration is unable to introduce complete. Therefore, in this issue of the journal, we only structure on the sound box and related components are introduced.
All rights reserved Copyright © 2014-2017 SUIM AUDIO CO.,LTD/KOREA