There are many ways to classify speakers, the common classifications are as follows:
1. Divided by purpose
Speakers can generally be divided into main speakers, monitor speakers, and return speakers.
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. The volume of the main speaker is generally larger.
Monitor speakers are used for program monitoring in control rooms and recording studios. They have the characteristics of low distortion, wide and flat frequency response, and little modification of the signal, so they can reproduce the sound effects of the program most truly. The appearance of monitor speakers is generally more delicate and compact. Due to its small size and outstanding sound quality, monitor speakers are often used in home Hi-Fi audio systems.
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, and even affect the performance. The back-to-listening speaker is generally made of a bevel.
Return to listening speakers
This kind of speaker can not only be placed on the stage without affecting the overall shape of the stage, but also allows people on the stage to hear clearly when the sound is played, and it will not feedback the sound to the microphone to cause howling.
2. According to the occasion
Speakers are divided into two categories: professional speakers and home speakers according to the occasion of use.
Household speakers are generally used for home playback. They are characterized by delicate and soft playback sound, more refined and beautiful appearance, not too high playback sound pressure level, and relatively low power.
Professional speakers are generally used in professional entertainment venues such as dance halls, karaoke halls, theaters, halls and stadiums. Professional speakers have high sensitivity, high sound pressure, and high power. Compared with home speakers, the sound quality of professional speakers is harder and the surface of the speakers is rougher for easy handling. So you always think that professional speakers look ugly in meetings, please forgive me.
3. According to the audio frequency
Speakers can be divided into full-band speakers, bass speakers and subwoofer speakers according to their audio frequency.
The so-called full-band speakers refer to speakers that can cover the low, mid and high frequency ranges. The lower limit frequency of the full-band speaker is generally 30-60Hz, and the upper limit frequency is 15-20kHz. (If you have a need for bass, please add a subwoofer, full-range speakers may not meet your taste buds), but in general small and medium-sized audio systems, only 1 pair or 2 pairs of full-band speakers can complete the sound 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 kind of speakers are generally used in large and medium-sized audio systems. Large and medium-sized speakers do not mean that they are non-domestic audio systems. Luxury home theaters all need this feeling to enhance the intensity 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.
4. According to the cabinet structure
According to the cabinet structure, the speakers can be divided into sealed speakers, inverted speakers, transmission line speakers, dumbbell speakers, etc. The enclosed sound box is the simplest speaker system. This kind of sound box is constructed by installing the speaker unit in a fully sealed box.
The airtight speaker is a tightly closed box with only speaker holes on the surface of the box. When the speaker is installed, the inside and outside of the speaker are closed and completely isolated. In this way, when the loudspeaker sounds, the sound waves in front and behind the diaphragm can be completely isolated without interfering with each other.
The airtight loudspeaker can completely isolate the radiated sound waves in front of the loudspeaker from the radiated sound waves behind the loudspeaker, but due to the existence of the airtight box, it will increase the resistance of the loudspeaker's movement, so the lower limit of the loudspeaker's frequency will increase. But having said that, closed speakers can get a good low-frequency sound, but this design method will reduce the efficiency of the speaker. If you want to get good control, you must use a large power amplifier to drive, otherwise its low-frequency signal The speed can feel a little slow.
Due to the low efficiency of closed speakers, they are rarely used in professional speakers, mainly for household speakers or a few monitor speakers. Sealed speakers have the advantages of simple debugging, wider frequency response, and better low-frequency transient characteristics in design and production, but they have higher requirements for speaker units.
Inverted speaker structure
Inverted speakers are also known as bass reflex speakers. There is an opening for the sound outlet on the cabinet panel of this speaker. There are various opening positions and shapes, but most of them are equipped with an inverted tube. . The sound waves radiated by the speakers in the sound box are inverted by the inverter tube, and then radiated to the front from the sound outlet, and are superimposed in phase with the sound waves radiated by the speakers in order to increase the low-frequency sound power.
Typical inverted speaker
Inverted speakers can provide a wider bandwidth than closed speakers, with higher sensitivity and less distortion. Ideally, the lower limit of the low frequency playback frequency can be more than 20% lower than the speaker resonance frequency. This type of speaker can reproduce rich low-frequency effects with a smaller cabinet. It is currently the most widely used type of speaker, and it is also my favorite speaker with the highest cost performance.
The diameter of the inverter tube of the inverter speaker and the length of the inverter tube will affect the extension of the low frequency. Therefore, the appropriate aperture and length must be designed according to the characteristics of the speaker to achieve the best sense of speed and good low frequency extension. . Inverted speakers are characterized by wide frequency response, high efficiency, and large sound pressure, which meet the requirements of professional audio systems. Therefore, inverted speakers are most commonly used in professional speakers.
Transmission line speakers are equipped with sound absorption behind the speakers
Transmission line speakers use a longer transmission pipe to increase the low frequency extension, but an excessively long pipe will cause the low frequency to be slow. Theoretically, the transmission pipe can attenuate the sound wave from the back of the cone to prevent it from being reflected to the open end and affect the sound radiation of the woofer. Its length is 1/4 or 1/8 of the wavelength of the low-frequency sound that needs to be raised. Usually, the sound transmission pipes of transmission line speakers are mostly folded in a labyrinth shape, so they are also called labyrinth or labyrinth speakers.
Transmission line speakers are also called 1/4 wavelength loaded speakers or QWL loaded speakers. A wedge-shaped tube with a length of 1/4 wavelength, closed at one end and open at the other end is added to the cabinet to install the speaker in The middle part of the pipe.
When the 1/4 wavelength of a certain frequency is equal to the length of the tube, the air column in the tube will resonate. When this resonant frequency is the same as the resonant frequency of the woofer, the tapered closed end of the box will produce the highest sound pressure, which will in turn act on the back of the speaker, and the excess airflow will radiate out from the opening.
The characteristic of the transmission line speaker is that the speaker can generate enough sound pressure load to control the amplitude, which can avoid distortion when the amplitude is large, and can also obtain a wavelength sound wave that is 4 times the length of the resonance tube.
The design idea of the transmission line speaker is completely different from the closed box or the inverted box. It uses a 1/4-wavelength transmission line to achieve the purpose of absorbing the resonance of the unit, suppressing the displacement of the diaphragm, and expanding the lower limit of the low frequency. Transmission line speakers have the following basic characteristics: a long pipe (transmission line) is connected behind the woofer, and the length of the pipe depends on the 1/4 wavelength of the unit's low-frequency resonance frequency (or a slightly higher frequency). In order to facilitate the actual production, the pipe is usually folded inside the box, which looks like a labyrinth; the cross-sectional area of the transmission line connecting the speaker unit is at least 25% larger than the radiation area of the unit, and then gradually becomes smaller, and the exit of the transmission line is just equal to the unit The radiation area of the diaphragm; damping materials such as wool or glass wool are laid in the transmission line. Compared with the design of a closed box and an inverted box, the transmission line speaker has a deeper bass.
Dumbbell speaker is a kind of speaker developed on the basis of inverted and closed speaker. Because its speakers are arranged like a dumbbell, it is called a dumbbell speaker.
Generally, the high frequency, mid frequency and low frequency speaker units on the front of the inverted speaker box and the closed speaker box are installed in a vertical arrangement. In this way, the high-frequency, mid-frequency, and low-frequency audio signals emitted by the speaker are radiated from different speaker units. Since these speaker units are distributed at different heights of the cabinet, people may think that sounds of different frequencies in the speaker come from different directions, thereby affecting the vertical positioning of the speaker. In order to overcome the shortcomings of the speakers in the vertical positioning performance, the vertical distance between the speaker units should be reduced as much as possible, and the use of dumbbell speakers can solve the problem of poor vertical positioning performance of the speakers to a certain extent.
Dumbbell speakers usually use a two-way structure. The two low frequency loudspeaker units in the dumbbell sound box can be connected in series or in parallel, and the high frequency loudspeaker unit is located in the middle of the two low frequency loudspeaker units.
Typical dumbbell speaker
If the two low-frequency speaker units have the same phase and sensitivity, the positioning accuracy of the sound effect can be effectively improved. In addition, because the dumbbell speaker uses two low-frequency speaker units, each speaker unit only needs to bear half the power under the condition of reaching the same output power, so that the amplitude of the cone can be greatly reduced. Non-linear distortion caused by basin vibration will also be significantly reduced. Therefore, dumbbell speakers can often output more power under the same distortion index.
Although dumbbell speakers have many advantages, the two low-frequency speaker units will interfere with each other when this type of speaker is working, making the mid-frequency vertical directivity of the speaker sharp (the direct consequence is that the midrange is not bright). In order to improve this situation, the crossover point of the speaker is usually selected lower, but this requires a higher performance tweeter unit to cooperate.
In order to maximize the sound reproduction effect of dumbbell speakers, the following two measures can be taken to improve: The technical parameters and frequency response characteristics of the two low-frequency speaker units should be as close as possible, and it is best to use the same type of speaker unit; The best effect is when the sensitivity of speakers and tweeters is 2 to 3dB lower than that of tweeters.
5. According to the cabinet shape and structure
The cabinet shape structure of the speaker is mainly divided into bookshelf type and floor type, as well as vertical type and horizontal type.
Floor-standing speakers are relatively large, and are generally placed directly on the ground, sometimes with foot spikes installed under the speakers. Due to the large volume of the cabinet and the convenience of using larger and more woofers, the floor-to-ceiling box usually has better low frequency, higher output sound pressure level and strong power carrying capacity, so it is suitable for larger listening areas or more comprehensive requirements. Occasion use.
Bookshelf speakers are small in size and usually placed on a tripod. They are characterized by flexible placement and do not take up space. However, due to the volume of the cabinet and the limitation of the size and number of woofers, their low frequency is usually lower than that of a floor cabinet, carrying power and output sound The pressure level is also smaller, suitable for use in a smaller listening environment.
Floor-standing speakers are large speakers with a cabinet height above 750mm; bookshelf speakers have a cabinet height below 750mm, those with 450～750mm are medium-sized bookshelf speakers, and those below 450mm are small bookshelf speakers.
Whether to use bookshelf speakers or floor-standing speakers depends on the size of the listening room, amplifier power and personal taste. Generally, for audio-visual rooms below 15 square meters, medium-sized bookshelf speakers should be used; small bookshelf speakers should be used for rooms less than 10 square meters; floor-standing speakers can be used for rooms larger than 15 square meters.
6. According to the form of power amplifier
According to whether there is a built-in power amplifier, speakers can be divided into passive speakers and active speakers. The former has no built-in power amplifier and the latter has. At present, more and more home speakers are active speakers, but subwoofers are usually active speakers. If your home is a passive speaker, remember to buy an amplifier!