The speaker is also called the speaker box. It puts the speakers working in different frequency bands in a specially designed cabinet. The output signal of the power amplifier is divided into high frequency, intermediate frequency, and low frequency signals through a frequency divider, and then sent to each corresponding A system in which speakers perform playback. There are many types of speakers, with different functional ranges and different classification methods.
Loudspeakers are also called speaker boxes, which assemble high, medium and woofer speakers in a specially designed cabinet, and send the high, medium and low frequency signals to the corresponding speakers through a crossover network for reproduction.
After the loudspeaker is installed in the loudspeaker, the propagation characteristics of the sound inside the loudspeaker can be used to expand the low-frequency reproduction range of the loudspeaker, so that the reproduced sound can produce a larger sound field.
Speakers are classified according to the frequency division method: single speaker speakers; two-way speakers; three-way speakers; four-way speakers; multi-way speakers; subwoofer speakers (subwoofers).
Speakers are classified according to their purpose: floor-standing speakers; bookshelf speakers; active speakers; surround speakers; monitor speakers; speakers for theaters; speakers for stage.
Speakers are classified according to their internal structure: closed, inverted, labyrinth, front horn, empty paper cone, symmetrical drive, Kelton, dumbbell, etc.
Classification characteristics of speakers
There are many ways to classify speakers. Common classifications in professional audio are as follows:
1. According to the occasion of use: divided into two categories: professional speakers and home speakers. Household speakers are generally used for home playback. They are characterized by fine and soft playback sound quality, more refined and beautiful appearance, not high playback sound pressure level, and relatively little power. Professional speakers are generally used in professional entertainment venues such as dance halls, karaoke, theaters, halls and stadiums. Generally, professional speakers have high sensitivity, high playback sound pressure, good power, and high power. Compared with household speakers, their sound quality is harder and their appearance is not very delicate. However, the performance of monitor speakers in professional speakers is similar to that of home speakers, and their appearance is generally more exquisite and compact. Therefore, such monitor speakers are often used in home HI-FI audio systems.
2. According to the audio frequency: can be divided into full-band speakers, bass speakers and subwoofer speakers. The so-called full-band speaker refers to the sound that can cover the low, mid and high frequency ranges. The lower limit frequency of the full-band speaker is generally 30Hz-60Hz, and the upper limit frequency is 15KHz-20KHz. In general small and medium-sized audio systems, only one pair or two pairs of full-band speakers can be used to fully take on the playback task. Bass speakers and subwoofers are generally dedicated speakers used to supplement the low frequency and ultra low frequency playback of full-band speakers. This type of speaker is generally used in large and medium-sized audio systems to enhance the strength and shock of low-frequency playback. When in use, after frequency division by an electronic crossover (crossover), the low frequency signal is sent to a special bass power amplifier, and then the bass or subwoofer speakers are promoted.
3. Divided by purpose: generally can be divided into main speakers. Monitor speakers and return speakers, etc. The main sound box is generally used as the main sound box of the sound system to undertake the main sound reproduction task. The performance of the main playback speaker has a great impact on the playback quality of the entire audio system, and a full-band speaker plus a subwoofer speaker can also be used for combined playback.
Monitor speakers are used for program monitoring in control rooms and recording studios. They have the characteristics of small distortion, wide and flat frequency response, and little modification of the signal, so they can most truly reproduce the original appearance of the program. Back-to-listening speakers, also known as stage monitor speakers, are generally used on stages or dance halls for actors or band members to monitor their singing or performance. This is because they are located behind the main sound box on the stage and cannot hear their own voice or the band's performance clearly, so they cannot cooperate well or can't find the feeling, which seriously affects the performance. Generally speaking, the return-to-listening speaker is made of a bevel shape and placed on the ground, so that it can be placed on the stage without affecting the overall shape of the stage, and it can be heard clearly by the people on the stage during playback, and the sound will not be fed back to the microphone. Howling.
4. According to the cabinet structure: it 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, and large sound pressure, which is in line with the type of professional audio system speakers, but because of its low efficiency, it is less in professional speakers Application, mainly used for household speakers, only a few monitor speakers adopt a closed box structure. The sealed speaker has the advantages of simple design and manufacture, wide frequency response, and good low-frequency transient characteristics, but it has higher requirements for the dial unit. 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. 1. The closed speaker is the simplest speaker system. It was proposed by FrederICk in 1923 and consists of a speaker unit installed in a fully sealed box. It can completely isolate the forward and backward radiated sound waves of the loudspeaker. However, due to the existence of the closed cabinet, the rigidity of the loudspeaker's motion mass to produce resonance is increased, and the lowest resonance frequency of the loudspeaker is increased. The sound and color of the airtight speaker is a little 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 airtight speakers use a suitably high Q value. Compliant speakers. Using 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 cushion speaker .
2. 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. The opening positions and shapes are various, but most of the holes are also equipped with sound tubes. 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, called the anti-resonance frequency. The sound waves radiated from the rear of the loudspeaker are inverted through the tube, and then radiated from the sound outlet to the front, and superimposed in phase with the sound waves radiated from the loudspeaker. It can provide a wider bandwidth than the closed type, with 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 type of speaker can reproduce rich bass with a smaller cabinet, and is currently the most widely used type.
3. Acoustic resistance speaker is essentially a deformation of an inverted speaker. It 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 to reduce anti-resonance. Frequency to broaden the bass replay band.
4. The transmission line speaker is named after the transmission line of the 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 and prevents them from being reflected to the open end and affecting the sound radiation of the woofer, but in fact, the transmission line speaker has a slight damping and tuning effect, which increases the speaker's resonance frequency near or below Acoustic output, and increase the bass output while reducing the amount of stroke. Usually, the sound ducts of this kind of speakers are mostly stacked in a labyrinth shape, so they are also called labyrinth or tortuous.
5. The passive radiating speaker 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 a non-magnetic circuit and voice coil. The empty paper cone (passive cone) is replaced. The radiation generated by the vibration of the passive cone and the forward radiated sound of the loudspeaker are in the same phase. The composite sound and passive cone formed by the air in the box and the passive cone support components The basin mass forms a resonance, enhancing the bass. The main advantage of this kind of speaker is that it avoids the unstable sound produced by the reflected sound hole, and it can obtain good sound radiation effect even if the volume is small, so the sensitivity is high, which can effectively reduce the speaker's working amplitude and the influence of standing waves. Small, the sound is clear and transparent.
6. The coupled cavity speaker is a cabinet 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 is the cone. One side is coupled with a closed box. The advantage of this kind of speaker is that the amount of air pushed by the speaker at low frequencies is greatly increased. Because 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 increases. In 1969, the A·S·W speaker released by Kawashima Yukihiko of Lo-d Japan is a coupled cavity speaker, suitable for reproducing bass without distortion with small-diameter long-stroke speakers.
7. For household type, the horn speaker is mostly in the form of a folding horn. Its horn mouth is coupled with a larger air load at the mouth, and the driving end has a small diameter. The back of this speaker is fully sealed and the chamber Most of the pressure is 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.