Basics speaker

The structure of the speaker

1, the speaker


There are many types of speakers: according to their energy conversion methods, they can be divided into electric, electromagnetic, piezoelectric, digital, etc .; according to the structure of the diaphragm, they can be divided into single paper cone, composite paper cone, composite horn, and A variety of shafts; according to the beginning of the diaphragm, it can be divided into cone type, dome type, flat plate type, belt type, etc .; according to the playback frequency, it can be divided into high frequency, intermediate frequency, low frequency and full band speakers; The form can be divided into external magnetic type, internal magnetic type, double magnetic circuit type and shielding type; according to the magnetic circuit nature, it can be divided into ferrite magnet, neodymium boron magnet, aluminum nickel cobalt magnet speaker; according to the diaphragm material Separate paper and non-paper cone speakers.

A. The dynamic speaker is the most widely used. It uses the interaction force between the voice coil and the constant magnetic field to make the diaphragm vibrate and sound. Electric bass speaker cone type to the majority, mostly mid-range speaker cone type or dome type, dome type tweeter places and belt, the horn is commonly used.

B, speaker cone structural simplicity, high energy conversion efficiency. The diaphragm material it uses is mainly pulp material, or blended with wool, silk, carbon fiber and other materials to increase its rigidity, internal damping and waterproof performance. The new generation of electric cone speakers use non-paper diaphragm materials, such as polypropylene, mica carbide polypropylene, carbon fiber textile, bulletproof cloth, hard aluminum foil, CD corrugation, glass fiber and other composite materials, performance improvement has improved.

C, dome speaker dome soft and hard top points of the ball. Vibrating diaphragm silk, silk, cotton cloth impregnated with phenolic resin, chemical fiber and composite materials of soft-ball loudspeakers are characterized by soft and reproducible sound quality. it features crisp sound reproduction.

D, radiation way horn loudspeaker cone speakers and different, which is in the diaphragm vibration, sound, and then spread out through the horn. Which is characterized by electro-acoustic conversion and a high radiation efficiency, distance, distortion, but the reproduction frequency band and narrow directivity.

E, with a voice coil speaker is directly formed on the entire diaphragm (aluminum film polyimide, etc.), direct coupling between the coil and the diaphragm. The alternating magnetic field produced by the voice coil interacts with the constant magnetic field, causing the belt diaphragm to vibrate to radiate sound waves. It is characterized by fast response speed, low distortion, fine playback sound quality and good sense of layering.

2, Box

Case for eliminating acoustic short-circuiting of the speaker unit, the sound resonance suppressing, broaden its frequency response, reduced distortion. The box structure of the speaker is divided into bookshelf type and floor type, as well as vertical type and horizontal type. The internal structure of another closed box, vented, with the general formula, empty cone type, labyrinth, symmetrical horn-driven and other forms, the most use is closed, vented, and with the general formula .

Floor-standing speakers are large speakers, the height of the cabinet is above 750MM, the height of the bookshelf speakers is below 750MM, the middle bookshelf speakers between 450MM and 750MM, and the small bookshelf speakers below 450MM.

Front main speaker home theater speaker system is vertical, there is the use of bookshelf, but also the use of floor-standing, which should be based on audio-visual room size, power amplifier size and personal preference. Generally, medium-sized bookshelf speakers should be used for audiovisual rooms below 15 square meters; small bookshelf boxes should be used for those less than 10 square meters; medium-sized bookshelf speakers or floor boxes can be used for rooms larger than 15 square meters. The front main speakers, center speakers and surround speakers are mostly in inverted phase design, followed by closed work and 1/4 wavelength loading type, labyrinth type and so on. In formula subwoofer with two openings and a dual-chamber type majority, followed vented, closed.

3. Frequency divider

The frequency divider has the power frequency divider and the electronic frequency divider, the main functions are frequency band division, amplitude frequency characteristic and phase frequency characteristic correction, impedance compensation and attenuation.

The power divider, also called passive post-stage divider, divides the frequency after the power amplifier. It mainly consists of passive components such as inductance, resistance and capacitance to form a filter network, and sends the audio signals of each frequency band to the speakers of the corresponding frequency band to replay. Characterized by low production costs, a simple structure, suitable for amateur production, but the insertion loss, low efficiency, poor transient behavior.

Electronic crossover is also called active front-end crossover. It is composed of various resistance-capacitance components and active devices such as transistors or integrated circuits. It is an analog placed in the signal lines of preamplifiers and power amplifiers. The electronic filter can divide the audio signal output by the preamplifier into different frequency bands, and then send it to the power amplifier for amplification processing. Its characteristic is that the frequency spectrum of each frequency band is balanced, the mutual interference is small, the output dynamic range is large, it has a certain amplification capacity, and the insertion loss is small. But the circuit configuration is relatively complicated.

Divider by sub-frequency band can be divided into two frequency, three frequency and divide. Divide the entire frequency band is divided audio signal into two high and low frequency bands; third frequency is a whole band is divided into high, medium and low three bands; divided by the third frequency divided into a plurality Ultra-low frequency band.

The crossover point and crossover slope directly affect the crossover quality (crossover frequency).
Crossover refers to two points of intersection speakers (e.g., divided by two in the treble and bass, treble and third frequency in alto, tenor bass) frequency response on a frequency adjacent, generally The frequency at the half of the power output of the two speakers (ie -3dB point) should be determined according to the frequency characteristics and distortion of the speaker and each speaker. Typically two frequency divider crossover takes between 1KHZ ~ 3KHZ, three-way and takes 250HZ ~ 1KHZ 5KHZ two crossover.
The crossover slope (also called the attenuation slope of the filter) is used to reflect the falling slope of the frequency response curve below the crossover point, expressed in decibels / octave (dB / oct). It has a first-order (6 dB / oct), second order (12 dB / oct), third order (18 dB / oct) and fourth-order (24 dB / oct) of the points, the higher the order, the frequency of the crossover point the greater the slope. More usually divide second order slope. Higher order frequency divider increase slope, but large phase shift; to produce lower-order dividing Lu more gentle slope and good transient response, but poor amplitude-frequency characteristics. High decided mainly bass filter order should take into account the good convergence of loudspeakers at the crossover point of the phase itself.


Speaker classification

Speaker shape varied, most commonly rectangular, closed box with a major, reflective box, transmission lines, passive radiator, the coupling cavity and to other types of horn box structure.

1, the closed box (Closed Enclosure) the simplest structure is a speaker system, 1923 mention made by Frederick, a speaker unit mounted in a hermetically sealed cabinets configuration. It can completely isolate the forward radiated sound wave and the backward radiated sound wave of the speaker, but due to the existence of the enclosed box, the rigidity of the resonance of the moving mass of the speaker is increased, and the minimum resonance frequency of the speaker is increased. The sound quality of the enclosed speakers 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-volume cabinet needs to be used. Most of the new enclosed speakers use a high Q value. Shun loudspeaker. Using the elastic effect of the quality of compressed air enclosed in the box, although the speaker is installed in a smaller box, the air cushion behind the cone will exert a counter-force on the cone, so this small enclosed speaker is also called an air cushion speaker .

2, the bass reflex speaker system (Bass-Reflex Enclosure), also known vented enclosure (AcousTIcal Phase Inverter), 1930 invented by the Thuras. There is a sound port opening in a panel on the case, a variety of openings in its position and shape of the load, but most are also equipped with sound conduit bore. The relationship between the internal volume of the cabinet and the sound tube hole, according to the principle of resonance, produces resonance at a specific frequency, called anti-resonance frequency. Rear speaker to sound waves radiated after the catheter is inverted, the sound radiated to the front of the mouth, in-phase superposition of radiated acoustic front speakers, it provides a wider bandwidth than closed, having a higher sensitivity, a smaller distortion. The ideal state, the bass reproduction limit frequency than the resonance frequency of the speaker as much as 20%. This kind of speaker can reproduce rich bass with a small cabinet, which is the most widely used type at present.

3, acoustic impedance speakers (AcousTIc resistance Enclosure) is essentially a modification of the phase inverted type speaker, a sound output port in which the buffer is filled within the conduit, the inverter control function as a semi closed box, so as to sound-absorbing material or structure , To reduce the anti-resonance frequency to broaden the bass playback frequency band.

4, transmission line speakers (Labyrinth Enclosure) is the classical transmission line theory named electrical, sound conduit is provided with sound absorption panels made behind the loudspeaker, its length is desired to enhance the low-frequency sounds 1/4 or 1 wavelength /8. Theoretically it decays back to the cone by the acoustic wave, which is reflected into the open end to prevent the effect of acoustic radiation woofer, but actually a transmission line having a speaker and a tuning slight damping effect, increases near the resonance frequency of the loudspeaker or less Acoustic output, and reduce the amount of stroke while enhancing bass output. Usually the sound ducts of such speakers are mostly stacked in a labyrinth, so they are also called labyrinth or labyrinth.

5, radiation passive speakers (Drone Cone Enclosure) is a branch of the bass reflex enclosure, also known as empty cone speaker, in 1954 the United States published by Olson and Preston, it's loud mouth opening of a no The magnetic circuit and the empty paper cone (passive cone) of the voice coil are replaced. The radiation generated by the vibration of the passive cone and the forward radiated sound of the speaker are in the same phase working state, and the composite formed by the air in the cabinet and the support assembly of the passive cone The smoothness and the quality of the passive cone form a resonance, enhancing the bass. The main advantage of this kind of speaker is to avoid the unstable sound reflected by the sound hole. Even if the volume is not large, a good sound radiation effect can be obtained, so the sensitivity is high, which can effectively reduce the working amplitude of the speaker and the impact of standing waves small, clear and transparent sound.

6, coupling cavities speaker box structure is an intermediate form between the closed and bass reflex, 1953 published US Henry Lang, ventilation holes outputs it from the output side of the driven cone, another cone side is coupled to a closed-box. The advantage of this kind of speaker is that the amount of air pushed by the speaker is greatly increased at low frequencies. Because the coupling cavity is a tuned system, when the cone movement is restricted, the output of the sound outlet does not exceed the sound output of the individual cone, which broadens the low frequency. Range, so the distortion is reduced and the withstand power is increased. In 1969, the A.S.W (AcousTIc Super Woofer) speaker released by Koshima Kawashima of Lo-d in Japan is a coupled-cavity speaker suitable for reproducing bass with small-diameter long-stroke speakers without distortion.

7, a horn speaker (Horn type Enclosure) in terms of the household type, the use of folded horn (Folded Horn) form, which is at the mouth of the horn flare and the large air load coupled to the drive end of a very small diameter, such a speaker The back of the box is fully sealed, and the pressure in the chamber is mostly on the back of the speaker cone. In order to maintain the balance of the front and rear pressure of the cone, the 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 enclosed speaker.


The type of speaker

1. Low-frequency loudspeaker-For various speakers, the quality factor of low-frequency loudspeaker-Q0 value requirements are different. For closed and inverted boxes, the Q0 value is generally between 0.3 and 0.6. In general, the larger the caliber of the low-frequency speaker, the diameter of the magnet and the voice coil, the better the low-frequency playback performance and transient characteristics, and the higher the sensitivity.
The structure of the woofer is mostly cone type, and a small amount is flat type. There are many types of woofer diaphragms, such as aluminum alloy diaphragm, aluminum magnesium alloy diaphragm, ceramic diaphragm, carbon fiber diaphragm, bulletproof cloth diaphragm, glass fiber diaphragm, acrylic diaphragm, paper diaphragm, etc. Bass units that use aluminum alloy diaphragms and glass fiber diaphragms are generally smaller in caliber and bear more power, while bass units that use reinforced paper cones and glass fiber diaphragms have a more accurate sound when replaying music and have a good overall balance.

2. Intermediate frequency speaker-Generally speaking, as long as the frequency response curve of the intermediate frequency speaker is flat, the effective frequency response range is larger than the width of the sound emission band it bears in the system, and the impedance is consistent with the sensitivity and the low frequency unit. Sometimes the power capacity of midrange is not enough, you can also choose a higher sensitivity, and the impedance is higher than the midrange of the bass unit, thereby reducing the actual input power of the midrange unit.
The midrange unit generally has two types: cone and dome. It's just that its size and power are larger than the tweeter and it is suitable for playing mid-range audio. The diaphragm of the midrange unit is mainly made of soft materials such as paper cones and silk membranes, and occasionally there are a small amount of alloy dome diaphragms.

3, tweeter - tweeter suggests that it is for high-frequency sound playback speaker unit. Its structure mainly number resolvent, cone type, dome-type and aluminum type and other categories.

A. Due to the strong directivity of the horn-type tweeter, powerful commercial sounds can be heard on the front of the horn. They are mostly used for high-power sound reinforcement, conference speakers and a small number of monitor speakers.

B, due to the tweeter cone diaphragm area is too large, too heavy, high-frequency characteristics as the other type tweeter, therefore more common in older speakers, in recent years have been gradually phased out.

C. The dome tweeter is currently the most commonly used tweeter in home speakers and small monitor speakers. The dome tweeter is divided into the dome structure and can be divided into a positive dome unit and an anti dome unit; from the dome material, it is divided into two categories: hard dome and soft dome.

D, hard dome tweeter diaphragm materials are aluminum, titanium, magnesium alloy, titanium alloy composite film, glass film, several kinds of diamond film. The treble played by the hard dome tweeter has a bright tone and a metallic feel. Suitable for playing popular music, movie music and effect music. The production of excellent aluminum alloy and titanium alloy composite membrane dome tweeters can also better express classical music and vocals.

E, soft dome tweeter diaphragm membrane materials are silk, silkworm line film, rubber film, and several ballistic cloth film. The treble of the soft dome tweeter when replaying music is smart and relaxed, and has a very good natural expression. In the performance of classical music, voice and other music listening with standard concepts, particularly handy. Especially in recent years, the treble of silk film and silk film ball, the upper limit of playback frequency has reached 40KHZ. In theory, the upper limit frequency of the tweeter should reach at least 20KHZ, the higher the better. But the unit with excellent high-frequency upper limit is more expensive.

F, unit item is the ball when playing music, the horizontal diffusion angle is bigger; anti-ball items tweeter when playing music, the horizontal radiation angle is small, but pure tone, power handling as well.

If you are a classical music lover and have strict requirements for color contrast during playback, you may wish to choose a soft-ball tweeter such as silk film. If your speakers also need to take care of karaoke and play movies, it is better to choose a hard dome unit. Of course, this is not absolute, because the playback sound of the speaker is related to the design of the crossover, the manufacture of the cabinet, and many other factors in addition to the unselected unit.

An appropriate mix of speakers and amplifier

There are a few points to note when choosing a speaker to match your power amplifier. First of all, it bears the ability to carry power. Some people say that this is very simple. The bearing capacity of the speaker is equal to the output power of the amplifier. Yes, but not so simple, one needs to know the same low-power amplifiers can drive the loudspeaker to generate sufficient bearing capacity of the volume with the other conditions, such as high sensitivity and impedance characteristics of the loudspeaker easily load, i.e. horn speaker having such characteristics . They have the ability to power a load, but high sensitivity to compare the speaker 96dB / w / m, only a fraction of one of its driving power required.

On the contrary, high-power amplifiers can also be used with speakers with lower carrying capacity when properly used. Although this is contrary to common sense, as long as the volume is carefully controlled, there is no problem. For example, a speaker amplifier match each side of the bearing capacity of only 50W to 100W normal volume to listen to not be dangerous, but high-power machine to avoid clipping, adds to the safety of work.

In fact, it is not safe to use a low-power amplifier to drive a loudspeaker with a large carrying capacity, which is beyond the expectations of general enthusiasts. Because the power supply is in short supply when the music signal of the amplified power returns to the power supply, resulting in clipping when the rated power is exceeded. At this time, a large amount of distortion will occur, which is a great threat to the speaker.

Impedance characteristics of the speakers is another worth considering that the speaker impedance is divided into two kinds of resistive and capacitive, resistive frequency domain representation throughout the large impedance changes, very irregular. We first need to know that the speaker impedance is based on the frequency change in the impedance of the printed product specifications given by the manufacturer only nominal impedance, or average impedance in fact the entire frequency domain can be depicted as a curve changing observe this curve can clearly understand the changes in impedance. An 8-ohm impedance speaker may be lower than 4 ohms or as high as 20 ohms at certain frequencies. Such a change is not surprising. The impedance of the electric speaker of a general speaker does not change much. The rated impedance is usually 4ohm to 8ohm. The impedance of electrostatic and flat speakers varies greatly, especially the electrostatic type. Its impedance changes very drastically, sometimes as low as below 1ohm. This kind of reactive load, low current work is not competent.

Most of the current power amplifiers are suitable for 4 or 8 ohm load resistance. A power amplifier with a large current capability can load an impedance below 4 ohm. A lower load impedance can output higher power. For example, a power amplifier with an 8 ohm load has a rated output power of 50. Watts, the best should be 100 watts for a 4 ohm load, but the load impedance cannot be reduced without limit, and the load capacity of this machine will be exceeded at a certain point. If you have a power amplifier with a large current output capacity, you can choose 8 ohms or less Impedance speakers, otherwise it is best to use 8 ohm or as low as 4 ohm speakers to be safe.

An ideally designed speaker should be suitable for listening to all kinds of music. This kind of speaker does not have its own timbre, but just faithfully plays back the recording. It does not increase or decrease the original sound. This is called neutral sound, but it is really neutral. little speaker. Some European products tend to this feature, the sound relatively simple, used to listen to the voice of the American people will feel bland.

Theoretically, the flatter curve of the speaker frequency should be as straight as possible, but in fact a loudspeaker whose frequency should be flat curve may not be beautiful. We can see that the measured frequency response curve of most speakers fluctuates at certain frequencies, and the frequency response curve of different speakers is not the same, which forms the difference in sound. Both the speaker crossover point as different, even if the other whole, were also sound. The designer can adjust the timbre with different crossover points to control the timbre to achieve his ideal effect.

Before choosing speakers These issues should be considered. Room size and the environment, and matching amplifier, even appearance has become selective focus.


British sound, sound European, American sound ......

On the current Hi-Fi sound system, speakers technically still a very weak link. As a kind of equipment that reproduces works of art as faithfully as possible, its faithful reproduction should be the first, but the current technology can only be a relative definition of faithful reproduction. This is also the sound characteristics of different brands of speakers. s reason. There are many varieties of speakers in today's world, but not many cost-effective ones. Overall, the majority of US efforts to good speakers, magnificent, suitable for playback of popular music; most soft and delicate English speakers, very musical, suitable for reproduction of classical music; Denmark, Germany, France and other European speakers, before the majority is somewhere between the two.

Due to the different design of the speakers and the parts used, the sound will be significantly different, so there are the so-called British sound, the east coast sound of the United States, the west coast sound of the United States, the European sound and the Japanese sound. These sounds are generally described as pure British sound warm, low bass, rich musicality, sound close to the east coast of the United States British sound, pay attention to the original sound and accurate regeneration, the West Coast sound of hearty vibrant, dynamic sound great pressure, especially for listening to rock For large-volume music, the European sound can be described in a simple way, focusing on accuracy and bass, which may be a little warmer and sweeter than the British sound. As for the Japanese sound, it is an ear-catching timbre, and intentionally creating some sound stains is actually harmonic distortion, which is attractive at first hearing, and it is easy to get tired for a long time.

Speaker manufacturers have to cater to the Hi-Fi fans hobbies and tastes, some factory specializes in manufacturing British sound or the East Coast sound speakers, selling to people who like to listen to classical music. When listening to classical music, the first accurate sound should be balanced with accurate frequency, the sound color should be reduced as much as possible, and it can produce a wide dynamic range. The manufacturers of the West Bank Sound in the United States sell to people who love rock, jazz and pop music. Listening to this kind of music pursues the stimulation of sound. The treble must be hearty and the bass is particularly strong. When listening, the body can directly feel the pressure of the music. As for the frequency should be balanced and do not consider, some manufacturers even deliberately making a sound stimulate the frequency response curve or add some harmonic distortion to please the consumer, rock and pop music fan does not count more than pure and quasi-sound, As long as the sound is exciting enough, it is attractive.

Of course, there are also manufacturers who pay great attention to the accuracy of the sound of the West Coast Sound speakers in the United States. Not all of them only pursue stimulation and ignore sound quality. In fact, there are many products of very high quality. Especially in recent years, speakers listening to rock and pop music have gradually paid attention to accurate sound balance, stereo sound is sharp, and sound stains are reduced. Powerful bass, high sound pressure and crisp tone.

Speaker of key performance indicators

1. Frequency range (unit: Hz): refers to the range from the lowest effective sound emission frequency to the highest effective sound emission frequency. The most ideal frequency range of the speaker is to replay the audible frequency range of the human ear evenly, namely 20HZ ~ 20000HZ. However, to replay at a large sound pressure level, the lower the frequency band, the structure subjected to large amplitude and the reduction of distortion must be considered, and the volume of the speaker generally needs to be increased. So the target should not be set too high, 50HZ ~ 16KHZ is enough, of course, 40HZ ~ 20KHZ is better.

2, the frequency response (unit: dB dB): refers to connect the audio signal a constant voltage outputted from the speaker system, when changing the frequency of the audio signal, the sound of the speakers produce pressure change with the frequency of the increase or attenuation and phase frequency dependent hysteresis phenomenon, a corresponding change in this relationship between sound pressure and phase and frequency is called frequency response. Frequency dependent sound pressure curve referred to as "amplitude-frequency characteristics", a frequency dependent phase lag of the curve referred to as "phase-frequency characteristics", both collectively referred to as the "frequency response" or "frequency characteristics." The amount of change is expressed in decibels. This index is an important indicator of quality assessing the merits of the speaker, the decibel value is smaller, the frequency response of the speakers, the flatter the curve, the smaller the distortion.

3. Pointed frequency characteristics: the frequency response curve clusters of the speakers measured in a number of prescribed sound wave radiation directions, such as 0 degrees, 30 degrees and 60 degrees in the horizontal plane of the central axis of the speaker. Figuratively, good directivity of the speaker as fluorescent, light can be uniformly spread to every corner of the room. Otherwise, it is like a flashlight.

4, the maximum output SPL: sound level indicator indicates the maximum speakers at maximum power input can be given.

5, the distortion (expressed as a percentage)

Harmonic distortion, refers to an increase of higher harmonic component in the original signal are not in the reproduction sound.
Intermodulation distortion, we know that the speaker is a non-linear device during the reproduction sound source, since the magnetic field inhomogeneity factors nonlinear deformation and support system of the magnetic gap, will produce a new kind of original signal frequency not component, so that when applied to the new frequency speaker with the original signal and the frequency signal, the modulation will produce another new frequency. In addition, the music signal is not a single-tone sine wave signal, but a multi-tone signal. When the two input signals of different frequencies at the same time the speaker, because a large nonlinear factors exist, two signal modulation will generate a new frequency signal, so that the burst frequency of the speaker's, in addition to the original signal, but also there were two For new frequencies that are not in the original signal, this distortion is intermodulation distortion. Its main influence is pitch (also known as pitch).
Transient distortion, the transient distortion of the speaker system, refers to a kind of transmission waveform distortion caused by the mass inertia of the speaker vibration system. Because there is a certain mass inertia of the speaker, so electrical shock cone can not keep changing moment, the heavy burst transmission waveform distortion, resulting in a change of tone frequency spectrum. The quality of this index is extremely important in the speaker system and speaker unit, which directly affects the restoration of sound quality and timbre.

6. Labeled power (unit: Watt W): the power marked on the speaker, two internationally popular labeling methods:
Long-term power or rated power, the former refers to the input of a specified analog signal to the speaker within the rated frequency range, the signal duration is 1 minute, the interval is 2 minutes, repeated 10 times, the speaker does not produce thermal damage and mechanical damage of the maximum input electric power. The latter means that the input sine wave signal to a speaker BORDER within the rated frequency range, the signal duration time is 1 hour, the speaker does not produce mechanical damage and thermal damage to the maximum sinusoidal power.
The maximum withstand power is the music power (MPO), which originated from the German Industrial Standard (DIN) and refers to the short-term maximum power that the speaker can withstand. This is because when playing music signal, the amplitude of the audio signal changes greatly, sometimes the peak power of music in a short time will exceed several times the rated power. The development of national standards GB9396-88 standard maximum power marked the noise power, maximum power of long-term, short-term maximum power, rated sine wave power. Speaker manufacturers usually use the long-term power or rated power as the marked power of the speaker.

7, the nominal resistance (unit: ohm [Omega]): refers to the ratio of the signal voltage U and the current loudspeaker input signal (as in the physics and high school, R = U / I). Because the impedance of the speaker is a function of frequency, the magnitude of the impedance value also changes with the frequency of the input signal. Preferred speaker impedance values ​​specified in our national standards 4Ω, 8Ω, 16Ω (international standard recommended value 8Ω), and provides a nominal impedance of the speaker: F0 to the second lowest among the F1 formant peak resonant frequency of the speaker impedance value. Some foreign loudspeaker manufacturers use the section where the impedance characteristic curve tends to be flat as the nominal impedance of the loudspeaker. The nominal impedance of the speaker is different from the nominal impedance of the speaker, because there is more than one speaker unit in the speaker, and the nature of each unit is also different. In addition, there are series or parallel crossover networks, so the standard specifies that the minimum impedance must not Below 80% of the nominal impedance value.

8. Sensitivity (unit: decibel dB): The sensitivity of the speaker refers to the measured sound pressure level (sound) at a distance of 1m from the geometric center of each speaker unit on the front of the speaker when the electric power input to the speaker in the speaker system is 1W The pressure is proportional to the amplitude and frequency of the sound wave, and the sound pressure level is an index indicating the relative magnitude of the sound pressure). It should be pointed out here that although sensitivity is an indicator of the speaker, it has nothing to do with the sound quality and timbre, it only affects the loudness of the speaker, and the input power can be used to increase the loudness of the speaker.

9, the efficiency (expressed as a percentage): speaker efficiency is defined, the electrical power input ratio of the acoustic power output of the speaker (i.e., acoustic - electric conversion percentage). A few days ago, the speakers on the market are usually marked with sensitivity, and some speakers are marked with efficiency, but they are expressed in decibels. This marked the wrong way, so that some consumer confusion about the sensitivity and efficiency of these two indicators. The two indicators of speaker sensitivity and efficiency have nothing to do with sound quality and timbre, and they are not standards for assessing quality. However, if the sensitivity and efficiency are too low, the input power of the amplifier must be increased to achieve the required sound pressure level.

How to choose speakers that satisfy you

Most speakers have a personality, which means that each speaker has a special tone, which must be paid attention to when choosing. Because there are often only personal hobbies between many speakers, not the advantages and disadvantages, and in the store environment, it is difficult to hear the differences in the musicality, sound image positioning and three-dimensional sense of audio equipment. The performance of different speakers has different characteristics of beauty. It can be said that each has its own strengths. The beauty of sound is the same as other arts. It shows different beauty with the owner's beauty.

Small speakers were originally made for convenient monitoring during mobile recording, and gradually became popular as the living environment became smaller. Bookshelf speaker, the original size is equivalent to the size of the airport, the volume is about 9L, a small speaker system placed on the bookshelf. Their high and low frequency sound waves radiated seamless unit, the radiation pattern is substantially spherical waves, a small speaker sound radiation closer to the ideal "point" source. This improves the sense of localization and sound field of stereo playback, and the small speakers have good transient response, small size, and easy positioning. It can be seen that the small speakers are particularly suitable for close listening in small rooms, playing string music, vocals and classical sketches with little dynamic. However, the low-frequency performance of general small speakers is different from that of large speakers, especially where dynamic momentum is required. As long as the environmental conditions permit, the use of small speakers should not be considered.

Floorstander speakers mostly use larger-caliber speaker units, such as 165MM, 200MM, and 250MM, which can play its thick low-frequency and majestic characteristics in a large room, so large speakers have a real sense of presence. But when it is used in a small room, there will be problems. Because the driving power of the standard sound village is reduced when the listening distance is close, so that the momentum of the speaker cannot come out, instead of lack of bass, and when it is too far away from the speaker, reflections in the room wall, furniture, etc. The non-direct sound is more and interferes with the direct sound, but affects the sound quality.

Some medium-sized speakers with a height of about 0.5 meters, between small and large speakers, are called standmounts abroad, and need to be placed on an appropriate tripod. Their performance is between small and large speakers and their strengths are full of certain characteristics.

Some low-efficiency expensive bookshelf noble speakers (known for being difficult to push) have very high requirements for power amplifiers. Not only the output power is large enough, but also the output current is large enough, and the damping characteristics are good, otherwise the effect is often not as good speakers. Such speakers are belong to brand DYNAUDIO AcousTIcs, Morel, ATC, Lynnfield Ensemble, and so on.

Pay attention to the following points before buying speakers

1, in addition to good spending budget, but you must have sufficient preparation. The preparation here refers to: first, you must wait until you have a sufficient understanding of the stereo before you can buy it, and it must not be carried out blindly; second, you must consider the home environment before buying, not to say that the home is even furnished It's hard to put it apart, but you have to buy back a pair of floor boxes.

2, before buying you must be a good bit of what the nature of the sound, so choose the speaker will be targeted, a pretty good idea.

3. Listen and watch more brands before buying. It is best to invite experienced professionals or music lovers to accompany you. However, the choice of speakers is very subjective. Even if the same amplifier and sound source are used with the same pair of speakers, there may be many enthusiasts, music lovers and even professionals who have different opinions on its sound quality evaluation. Therefore, after careful and careful selection and approval by most people around, everyone should rely on their ears to appreciate, identify, listen to music, and improve their artistic cultivation through continuous appreciation.
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