◠What are the components of the speaker? There are all kinds of speakers on the market, but no matter which one is composed of the two most basic parts of the speaker unit (the term speaker unit) and the cabinet, in addition, most speakers use at least two or more The speaker unit implements the so-called multi-channel audio reproduction, so the frequency divider is also an indispensable part. Of course, there may be other components in the speaker, such as sound-absorbing cotton, inverted tubes, folded "labyrinth pipes", ribs / reinforced partitions, but these components are not essential for any speaker. The most basic composition of the speaker The element has only three parts: the speaker unit, cabinet and crossover. ◠Why do some speakers use two speaker units, while some use three, and some use four or five, do you use one? The speaker unit plays the role of electro-acoustic energy conversion, and converts the electrical signal sent by the power amplifier into sound output. It is the most critical part of the speaker. The performance index and sound quality performance of the speaker depend greatly on the performance of the speaker unit, so The prerequisite for making a good speaker is to choose a speaker unit with excellent performance. The performance requirements of the speaker unit are summarized in terms of high load power, low distortion, wide frequency response, good transient response, and high sensitivity, but it must also take into account distortion in a wide full frequency range of 20Hz-20kHz. , Transient, power and other performance is very difficult, just like the road police, if it is too wide, it will certainly lose sight of each other, and each tube is much easier, the same is true for the speaker unit, the most effective solution is to divide the frequency band playback. To this end, the speaker factory produces different types of units, some of which are only responsible for playing bass, called the bass unit, the midrange unit is called the midrange unit, and the tweeter unit is only responsible for playing the treble, so that a targeted design can be adopted to The performance of this kind of unit is relatively good. Therefore, although a full-band speaker can be used to design the speaker, for the above considerations, the design method of covering the entire audio frequency band with a combination of multiple units still accounts for the vast majority. The number of units used depends on the frequency division method of the audio range. If it is a two-way speaker that is simply divided into two sections: treble and bass (or mid-low), choose two speakers with one high and one low (or medium-low) Enough; if it is a three-way loudspeaker with high, middle and low three-segment speakers, at least three units must be used. Now the design method of two woofers working in parallel is also very popular, so that the total number of units may reach Four; the frequency band of some large speakers is more finely divided, if you use the design of the unit working in parallel, the total number of speaker units will be more. In the speaker information or manual, there is usually the text "X channel X unit", which is a specific description of the number of frequency division channels of the speaker and the total number of units used, such as "three channel four units", indicating that this is a three-way design The speakers used a total of four speaker units, and so on. ◠What is the frequency divider used for? Since the current speakers almost all adopt the design method of multi-unit sub-band playback, there must be a device that can divide the full-band music signal sent by the power amplifier into treble, bass output or treble, midrange, and bass output as needed. In order to connect with the corresponding speaker unit, the crossover is such a device. If the full-band signal is directly sent to the high, middle and bass units without distribution, the part of the "excess signal" outside the frequency response range of the unit will adversely affect the signal restoration in the normal frequency band, and may even cause The treble and midrange units are damaged. From the circuit structure point of view, the crossover is essentially an LC filter network composed of capacitors and inductors. The treble channel is a high-pass filter, which only passes high-frequency signals and blocks low-frequency signals; the opposite is true for the bass channel. Bass passes to block high-frequency signals; the midrange channel is a band-pass filter, except that the frequency between the two crossover points of one low and one high can pass, and both high-frequency and low-frequency components will be blocked. In the actual frequency divider, in order to balance the sensitivity difference between the high and low units, attenuation resistors are also added; in addition, some frequency dividers also include an impedance compensation network composed of resistors and capacitors, the purpose of which is to Make the impedance curve of the speaker as flat as possible to facilitate the power amplifier drive. ◠What types of speaker units are there? There are many types of speaker units, and the classification methods are also different. If it is divided according to the principle of electro-acoustic conversion, there are different types of units such as electromagnetic type, electric type, electrostatic type, piezoelectric type, etc. The most commonly used is the electric type unit; according to the shape of the unit diaphragm, there are cone Units, flat units, dome units, belt units, etc. Among them, cone units and flat units are more suitable for bass and midrange, while dome units and belt units are more suitable for treble, and some midrange units use balls Top design; from the perspective of the frequency band covered, the speaker unit can be divided into a bass unit, a midrange unit, a tweeter unit and a full band unit. At present, the most common bass unit and midrange unit belong to electric speakers in terms of transduction principle. They mostly use cone-shaped diaphragms, because the shape of the diaphragm is mature and has good performance. There are many kinds of diaphragm materials, including traditional paper diaphragms, diaphragms made of polymer synthetic materials (such as polypropylene), and diaphragms made of metal materials such as aluminum and magnesium. The requirements for the diaphragm are good rigidity (not easy to produce split vibration), light weight (good transient response), and appropriate internal damping characteristics (suppression of resonance), but these requirements are not easy to meet at the same time. The weight of the paper diaphragm And the damping characteristics can meet the requirements, but the rigidity is not strong enough; the rigidity of the metal diaphragm is very good, but the damping is not good; the polypropylene diaphragm takes into account all aspects relatively well, and has gained more applications in recent years. In addition, some manufacturers use a very complicated process to manufacture the diaphragm. The "sandwich" composite structure is one of them. The middle layer of the honeycomb structure is sandwiched between its upper and lower surfaces, which has a high rigidity as a whole. It has the characteristics of light weight and good damping, which is very promising. The tweeter is the most commonly used dome tweeter, which also belongs to the electric unit in terms of working principle. The dome tweeter's diaphragm can be made of metal materials (such as aluminum, titanium, beryllium, etc.), which is called a hard dome, or it can be made of a soft fabric (such as silk, chemical fiber), which is called a soft dome, usually, a hard ball The high frequency response of the dome is better, while the soft dome sound is softer. In recent years, band tweeters and electrostatic tweeters have also been applied. Their common advantage is that the diaphragm is particularly light, so the high frequency response is excellent, and the sound is delicate and transparent. However, the production of these two tweeters is not as easy as the dome tweeters. , The application is not very popular. There is also a horn treble, which is composed of a dome-shaped driving part plus a trumpet-shaped horn. It is characterized by strong sound directivity and high efficiency, so it is widely used in speakers in the field of professional sound reinforcement. There is also a coaxial unit, which is actually a combination of bass and treble units. For specific characteristics, please refer to the relevant question and answer. ◠Why should the speaker unit be installed in the box? Would it be okay not to pack them, for example, to fix them with a bracket? No, to be precise, the bass unit must be packed, but the treble can be installed or not. There are two reasons why the bass unit must be packed in a box: one is to eliminate the "acoustic short circuit" phenomenon; the other is to suppress the low-frequency resonance peak of the speaker unit. Let me talk about the first reason first. When the diaphragm of the woofer moves back and forth, in addition to the sound waves radiating forward, there are also sound waves radiating backward. The phases of the sound radiation in the two directions are exactly opposite, that is, they are 180 degrees apart. Because the wavelength of low-frequency sound waves is very long, its diffraction ability is very strong, that is to say, the directionality of low-frequency sound waves is very weak. If the speaker unit is not boxed, the backward radiated sound waves will go to the front and the front The radiation cancels out of phase, and the overall forward sonic radiation energy is greatly weakened. This phenomenon is called "acoustic short circuit". The "acoustic short circuit" phenomenon must be eliminated, otherwise low frequencies cannot be radiated effectively. If the speaker unit is installed in the box, the radiation behind the diaphragm is blocked by the box, so there will be no "acoustic short circuit". The second reason is that each motorized low-frequency unit has a low-frequency resonance point. The output at this resonance point reaches a peak, but the distortion is also very high, and the transient response is very poor. If this resonance peak is not suppressed , Will inevitably seriously affect the sound quality of the playback. If the unit is boxed, the stiffness of the air in the box will inhibit the movement of the diaphragm, thus achieving the purpose of suppressing the resonance peak and improving performance. In addition, by reasonably selecting the structure and parameters of the cabinet, the purpose of broadening the low-frequency response can be achieved. A well-designed inverter box, passive radiator speaker, and transmission line speaker can obtain such effects. Why can't the tweeter be packed? Because the wavelength of the tweeter is short, the diffraction ability is weak, there is no "acoustic short circuit" phenomenon, and it is not necessary to suppress the low-frequency resonance peak like the woofer, so the function of the speaker is only a support for the tweeter. ◠What materials are generally used for the cabinet? The cabinet is generally made of wooden materials, because the wood is easy to process, and after the surface treatment, it can get the same texture as the furniture, and it is easy to coordinate with the living room environment. At present, the most commonly used material is artificial medium density fiber (MDF) board. This material has high strength, is not easy to deform, does not crack, and the surface is very smooth. It can be directly glued with wood veneer or PVC decoration without sanding. Some speakers also use particle board to make the box. The particle board also has the characteristics of not easy to deform and crack, and the surface is flat. The strength is also acceptable, but once it is damp, it is easily damaged, so it is usually only used for cheap low-end speakers. There are also boxes made of natural solid wood panels, but the cost of natural solid wood is relatively high, and it is easy to crack and deform due to improper handling, so it has been used less and less in recent years. It is generally used only for high-end speakers, mainly because the texture of solid wood is relatively high ( Especially precious wood) this advantage. Of course, the cabinet does not have to be made of wood, plastic, metal or even slate can be used, but speakers made of these materials are not common. ◠Is the sound of solid wood speakers better than wood-based speakers? Can't say that. In theory, as long as the cabinet is strong enough to not vibrate, there is no difference in what materials are used. The sound of the speaker is mainly determined by the three major elements of the speaker unit, the design of the cabinet structure, and the frequency divider, and it has nothing to do with whether the cabinet material is solid wood or artificial board, or even plastic or metal. ◠How are speakers classified? The classification of speakers has different angles and standards. According to the acoustic structure of the speakers, there are closed boxes, inverted boxes (also called low-frequency reflection boxes), passive radiator speakers, and transmission line speakers. For their respective characteristics, see details. Related question and answer. Inverted boxes are the current mainstream in the market; judging from the size and placement of speakers, there are floor boxes and bookshelf boxes. The former is relatively bulky and is generally placed directly on the ground, and sometimes shock-absorbing feet are also installed under the speakers. nail. Due to the large volume of the cabinet and the convenience of using larger and more bass units, the floor box is usually better at low frequencies, and has a higher output sound pressure level and strong power carrying capacity, so it is suitable for larger listening areas or more comprehensive requirements. Use in occasions. The bookshelf box is small and usually placed on a tripod. It is characterized by flexible placement and does not occupy space. However, due to the volume of the box and the size and number of the woofer, its low frequency is usually not as good as the floor box, carrying power and output sound pressure. The level is also smaller, suitable for use in smaller listening environments; it is divided according to the narrow bandwidth of the playback, there are wideband speakers and narrowband speakers, most speakers are designed to cover the widest possible frequency band , Belonging to a wide-band speaker. The most common narrow-band speakers are the subwoofers (subwoofers) that have emerged with home theaters. They are only used to restore a very low frequency range from ultra-low frequency to low frequency; according to the presence or absence of a built-in power amplifier, they can be divided into passive speakers and For active speakers, the former has no built-in power amplifier and the latter has. Most current home speakers are passive, but subwoofers are usually active. ◠What are the characteristics of the closed box? The speaker unit of the sealed speaker is installed in a completely sealed box, so that the reversed sound waves radiated backwards by the diaphragm are completely blocked by the box, and will not run outside the box and cancel out the positive phase sound waves in front of the diaphragm. Solve the "acoustic short circuit" problem, so that the bass can effectively radiate. The low-frequency attenuation characteristics of the closed box are gentler than other types of speakers, and form the same attenuation curve as a second-order low-pass filter, which means that it has the best transient response of all types of speakers. At the same time, the air enclosed in the box forms a strong "air spring", which can effectively suppress the displacement of the diaphragm at the resonance frequency and reduce nonlinear distortion. However, the stiffness of the air also increases the low-frequency resonance frequency of the speaker unit, so that the overall low-frequency lower limit of the speaker box is higher than that of the unit under free space conditions. Compared with the design of inverter box and transmission line speaker, the low frequency of the closed box The lower limit is relatively worse. Also, the backward radiation of the diaphragm is not used, resulting in lower efficiency. ◠Is the air cushion speaker and closed speaker the same thing? The air-cushion speaker was first patented by H. Olson and his partner J. Preston in the United States, and was promoted by AR in the 1950s. The representative product was the well-known AR-3 at that time (Hong Kong and Taiwan enthusiasts called it " A third brother "). The air cushion speaker is a kind of closed box. It is characterized by the use of a highly compliant speaker unit and the design of the box body is small enough so that the stiffness of the air in the box is much higher than the stiffness of the unit vibration system (generally more than 3 For the vibration system of the unit, the effect of the air in the box on it is like an elastic air cushion, so this speaker is named. Air-cushion speakers have low distortion and good transient performance, and were once very popular. However, due to the use of high-compliance units, the sensitivity of such speakers is generally low. ◠What are the characteristics of the inverter box? The inverter box is the most commonly used speaker at present. It adds a duct (inverted tube) on the basis of the closed box. One end of the duct is connected to the air in the box, and the other end passes through the opening in the box wall (inverted port ) To the outside of the box. When the diaphragm of the horn unit moves, on the one hand, it directly radiates sound waves to the outside, and on the other hand, it compresses (or expands) the air in the box, so that the air in the box is discharged from the inverting port, so that the inverting port becomes The "second diaphragm" that drives air, if ingeniously designed, the inverter tube-box system can just invert the sound waves radiated backwards by 180 degrees from the diaphragm (the inverting box gets its name), so from the opening The radiated sound wave is in phase with the sound wave radiated in front of the diaphragm, and the in-phase radiation superimposes the sound energy, thus enhancing and extending the overall low frequency response of the speaker. Compared with the closed box, the same box volume can obtain a lower low-frequency extension, and because the clever use of the backward radiation energy of the diaphragm, the efficiency is relatively high. However, the inverter box is not perfect. In addition to the difficulty of design and debugging than the closed box, the rapid flow of air at the opening is likely to cause airflow noise. In addition, the phase reversal effect is essentially achieved using acoustic resonance, so the transient response of the sound wave radiated by the opening is relatively poor. ◠What are the characteristics of passive radiator speakers? The passive radiator speaker, also called the empty paper cone speaker, is actually a variant of the inverter box. Its working principle is very similar to the inverter box, except that the inverter tube is replaced by a passive radiator. The structure of the passive radiator is similar to the speaker unit. It has a fold ring and a diaphragm that radiates sound waves, but there is no voice coil and magnetic circuit system. The movement of the diaphragm is completely controlled by the air in the box. The characteristics of passive radiation speakers are similar to those of inverting boxes, that is, a smaller box can obtain better low-frequency response and higher efficiency, but it also has characteristics that are different from inverting boxes. The advantage of the inverter box is that it overcomes the problem that the inverter port is prone to airflow noise, but the passive radiator speaker has a steeper low-frequency attenuation characteristic than the inverter box, which means that the transient response is worse than the inverter box. American Polk Audio is the most representative manufacturer of passive radiator speakers. ◠What is special about the transmission line speaker? The design idea of ​​the transmission line speaker is completely different from the closed box or inverted box. It uses the 1/4 wavelength transmission line to achieve the purpose of absorbing unit resonance, suppressing diaphragm displacement, and expanding the lower limit of low frequency. Transmission line speakers have the following basic characteristics: a long tube (transmission line) is connected to the woofer, and the length of the tube is 1/4 wavelength of the low-frequency resonance frequency (or a slightly higher frequency) of the unit. For practicality, the tube is usually Folded inside the box, it looks like a labyrinth; the cross-sectional area of ​​the transmission line connected to the speaker unit is at least 25% larger than the radiation area of ​​the unit, and then gradually becomes smaller, and the exit area of ​​the transmission line is just equal to the radiation area of ​​the unit diaphragm; Damping substances such as wool or glass wool are laid inside. Transmission line speakers have deeper bass sounds than designs such as airtight boxes and inverter boxes, but some people represented by British famous speaker expert MarTIn Colloms believe that transmission line speakers are more difficult to avoid sound stains caused by transmission line resonance. The world premiere of the technical zone! ROHM has developed the power supply IC "BD372xx series" for high-quality audio. A practical guide for the purchase of home wireless routers. Understanding the circuit diagram and working principle of the audio. Talking about the "frequency response curve" in the audio. Deep dismantling report of the M0pro speaker: both internal and external  Follow WeChat Interesting and informative information and technical dry goods  Download Audiophile APP Create your own personal electronic circle  Follow the audiophile class Lock the latest course activities and technical live broadcast Collect People collection share it: related suggestion Questions and answers about the basic knowledge of speaker purchase ◠What are the components of the speaker? & nb ... Published on 2006-04-17 23:41 • 169 times read ![Questions and answers about the basic knowledge of speaker purchase]() Questions and answers about the basic knowledge of speaker purchase (below) ◠What is a coaxial speaker? In general ... Published on 2006-04-17 23:36 • 211 times read ![Questions and answers about the basic knowledge of speaker purchase (below)]() ![]() '+ data.username +'
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