Follow WeChat Download Audiophile APP Follow the audiophile class related suggestion It is precisely because of fever and audio equipment that has promoted the development of audio equipment and the improvement of cultural taste. Therefore, fever activities are welcomed by the public. As for the hair ... Long-term evolution (LTE) wireless networks present several challenges to test equipment vendors. The LTE air interface defined by 3GPP adopts positive ... 1. Composition principle, exchange method and applicable scope of data communication 1. Composition principle of data communication DTE is a data terminal. Data terminals are grouped ... This article introduces the various components of the data acquisition system in detail and explains the most important guidelines for each component. This article also defines the number used for PC-based ... At present, there are mainly several types of touch screens, which are: resistive (double layer), surface capacitive and inductive capacitive, surface acoustic wave, infrared ... This application note will introduce power measurement terms, explain the different options available for floating measurements, and highlight the advantages and disadvantages of each option. ... The national standard GB7665-87 defines the sensor as: "A device that can feel the specified measured and converted into a usable signal according to a certain rule ... The oscilloscope has already become one of the most effective tools for detecting electronic circuits. By observing the voltage and current waveforms of key nodes of the line, you can intuitively check the line ... Basic knowledge of LCD display ☆ Resolution ... This article introduces TVS, glass discharge tube, varistor, ceramic gas discharge tube, semiconductor discharge tube, self-recovery insurance ... PoC basics PoC-Push to Talk over Cellular & nb ... Hard disk basics When you talk about hard disks, you must be familiar with them. My Windows 98 is installed on the hard disk, and my hard disk ... Digital camera repair basic knowledge Digital camera is also called digital camera, referred to as DCS (Digital Still Camera ... "Display Maintenance Basics" & nbs ... 1 Standard parts The composition of single chip ... Section 1 Identification of Common Components 1. Resistance "R" is used in the circuit ... Lecture 1: Characteristics of Capacitors (Cross-to-Direct) All kinds of capacitors: First, the significance of electronic circuit diagrams Circuit diagrams are for people to study and engineering ... Section 1 Identification of Common Components 1. Resistance "R" is used in the circuit ... The electric remote control toy also adds a remote control circuit to the electric toy. Common remote control circuits are ... 目的：基于实际ç»éªŒä¸Žå®žé™…项目详细ç†è§£å¹¶æŽŒæ¡æˆä¸ºåˆæ ¼çš„硬件工程师的... ... ... å°åˆ·ç”µè·¯æ¿ï¼ˆPrinted circuit board，P... æ— çº¿ç”µåŸºç¡€çŸ¥è¯†ä¸€ã€æ— 线电通信åè¯è§£é‡Šã€éŸ³é¢‘】åˆç§°å£°é¢‘，是人耳所能... 在我们的日常生活ä¸ï¼Œç»å¸¸çœ‹åˆ°æˆ–用到å„ç§å„æ ·çš„ç‰©ä½“ï¼Œå®ƒ... 表å¾å¤©çº¿æ€§èƒ½çš„主è¦å‚数有方å‘图，增益，输入阻抗，驻波比，æžåŒ–æ–¹å¼... '+ data.data.username +' '; dom + ='
Flat Twin Cables
they are suitable for power & lighting circuits and building wiring. Also suitable for use as an earth wire the internal wiring of appliances and apparatus.
- Standard applied: BS 6004
- U0/U: 300/500V
- Certification: Third party test reports available
- Flame retardant or fire resistance or Low smoking and Halogen free or other property can be available
Flat Twin Cables,Flat Twin Wires,Outdoor Electrical Cable Types,Twin Flat Flexible Cable Shenzhen Bendakang Cables Holding Co., Ltd , https://www.bdkcables.com The structure of the speaker
1. 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; according to the magnetic circuit 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; 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. Most of the electric woofers are cone type, the mid-range speakers are mostly cone type or dome type, and the tweeters are usually dome type, belt type and horn type.
B. The cone type speaker has a simple structure and 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. The dome speakers are divided into soft domes and hard domes. 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. Its characteristic is that the replay sound quality is crisp.
D. The radiating method of the horn type speaker is different from the cone type speaker. This is after the diaphragm vibrates, the sound diffuses out through the horn. It is characterized by high electro-acoustic conversion and radiation efficiency, long distance and low distortion, but the playback frequency band and directivity are narrow.
E. The voice coil of the band speaker is directly made on the whole diaphragm (aluminum alloy polyimide film, etc.), and the voice coil is directly coupled with 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. Cabinet
The cabinet is used to eliminate the acoustic short circuit of the speaker unit, suppress its acoustic resonance, widen its frequency response range, and reduce 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 the box has closed, inverted, belt type, empty paper cone, labyrinth, symmetrical drive and horn type. The most used are closed type, inverted type and belt type .
Floor-standing speakers are large speakers, the height of the cabinet is above 750MM, the height of the bookshelf speakers is below 750MM, those between 450MM and 750MM are medium-sized bookshelf speakers, and those below 450MM are small bookshelf speakers.
The front main speakers of the home theater system are upright speakers, some of which use bookshelves, and some use floor-standing, which depends on the size of the listening room, the power of the power amplifier, 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. Subwoofer speakers are mostly of the band type and double-cavity double-opening type, followed by the inverted type and closed type.
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. Its characteristics are low production cost, simple structure, suitable for amateur production, but large insertion loss, low efficiency, and poor transient characteristics.
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.
The frequency divider can be divided into two frequency division, three frequency division and four frequency division according to the frequency division frequency band. Two-way frequency is to divide the entire frequency band of the audio signal into two frequency bands of high frequency and low frequency; three-way frequency is to divide the entire frequency band into three frequency bands of high frequency, intermediate frequency and low frequency; Ultra-low frequency band.
The crossover point and crossover slope directly affect the crossover quality (crossover frequency).
Crossover point refers to the intersection of the frequency response curves of two adjacent speakers (such as treble and bass in the second frequency division, treble and midrange in the third frequency division, midrange and bass) at a certain frequency, usually 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. Usually, the frequency dividing point of the two-way frequency divider is between 1KHZ ~ 3KHZ, and the three-way frequency point is two frequency points of 250HZ ~ 1KHZ and 5KHZ.
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 is divided into first order (6 dB / oct), second order (12 dB / oct), third order (18 dB / oct) and fourth order (24 dB / oct), the higher the order, the frequency after the crossover point The greater the slope of the curve. The more commonly used is the second-order crossover slope. High-order frequency dividers can increase the slope, but the phase shift is large; low-order frequency dividers can produce a gentler slope and a good transient response, but the amplitude-frequency characteristics are poor. Deciding the order of high and low frequency filtering should mainly consider the problem of good connection of the phase of the speaker itself at the crossover point.
Speaker classification
The shape of the speaker is varied, and the common ones are mostly rectangular. The main structure of the box is sealed box, reflective box, transmission line, passive radiator, coupling cavity and horn.
1. The closed enclosure (Closed Enclosure) is the speaker system with the simplest structure. The 1923 was proposed by Frederick and consists of a speaker unit installed in a fully sealed box. 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. Compliant speakers. 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. Bass-Reflex Enclosure, also known as AcousTIcal Phase Inverter, was invented by Thuras in 1930. There is a sound outlet opening in its load on a panel of the cabinet. There are many positions and shapes of the opening, but most of them are also equipped with sound ducts in the hole. 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. The backward radiated sound wave of the speaker is reversed through the duct, and then radiated to the front from the sound outlet, which is superposed in phase with the forward radiated sound wave of the speaker. distortion. Ideally, the lower limit of the low-frequency playback frequency can be as much as 20% lower than the speaker resonance frequency. This kind of speaker can reproduce rich bass with a small cabinet, which is the most widely used type at present.
3. Acoustic resistance enclosure (AcousTIc resistance Enclosure) is essentially a deformation of an inverting type speaker. It is filled with sound absorbing material or structure in the sound outlet duct and acts as a semi-closed box to control the inverting function to make it buffer. , To reduce the anti-resonance frequency to broaden the bass playback frequency band.
4. The transmission line speaker (Labyrinth Enclosure) is named after the transmission line of classical electrical theory. There is a sound duct made of sound-absorbing wall plate behind the speaker, the length of which is 1/4 or 1 of the wavelength of the low-frequency sound to be raised. /8. In theory, it attenuates the sound waves coming from behind the cone to prevent it from being reflected to the open end and affect the sound radiation of the woofer, but in fact the transmission line type speaker has a slight damping and tuning effect, increasing the speaker at or near the resonance frequency 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. Passive radiant speaker (Drone Cone Enclosure) is a branch of bass reflex speaker, also known as empty paper cone speaker. It was published by Olson and Preston in the United States in 1954. The empty paper cone (passive cone) of the magnetic circuit and voice coil is 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. 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. The coupled cavity speaker is a box structure between the closed type and the bass reflex type. It was published by Henry Lang of the United States in 1953. Its output is output by the sound hole driven by one side of the cone, and the cone is another. One 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. Horn type enclosure (Horn type Enclosure) For home use, it is mostly in the form of a folded horn (Folded Horn). Its horn mouth is coupled with a large air load at the mouth, and the diameter of the driving end is very small. 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.
Types of speakers
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. High-frequency speaker-the tweeter is, as the name suggests, a speaker unit for playing back high-frequency sounds. Its structure is mainly divided into several types such as number solution type, cone type, dome type and aluminum belt type.
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. The cone-type tweeter is too large and heavy, and the high-frequency characteristics are not as good as other types of tweeters. Therefore, it is more common in old-style speakers and has been gradually eliminated in recent years.
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. The diaphragm materials of hard dome tweeters include aluminum alloy, titanium alloy, magnesium alloy, titanium alloy composite membrane, glass membrane, diamond membrane and so on. 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. The diaphragm material of soft dome tweeter includes silk membrane, silkworm membrane, rubber membrane and bulletproof cloth membrane. The treble of the soft dome tweeter when replaying music is smart and relaxed, and has a very good natural expression. It is especially handy when expressing classical music, vocals and other music with standard listening concepts. 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. When the positive ball unit plays music, the horizontal diffusion angle is larger; when the anti-ball unit tweeter plays music, the horizontal radiation angle is smaller, but the tone is pure and the power is also greater.
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.
Proper matching of speakers and amplifiers
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. Not bad, but it is not so simple. You need to know that a small power amplifier can drive a large-capacity speaker to produce sufficient volume under other conditions. For example, the speaker has high sensitivity and the impedance characteristic is easy to load. The horn type speaker has this characteristic. . They have the ability to load high power, but compared to speakers with a sensitivity of up to 96dB / w / m, the required driving power is only a fraction of it.
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, using a 100W amplifier on each side and a speaker with a carrying capacity of only 50W to listen at normal volume will not be dangerous. On the contrary, a high-power machine can avoid clipping and increase work safety.
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. In severe cases, it can burn the speaker voice coil.
The impedance characteristics of the speaker is another point worth considering. The impedance of the speaker is divided into two types: resistive and capacitive. Resistivity means that the impedance changes greatly and is very irregular in the entire frequency domain. We first need to know that the impedance of the speaker changes according to the frequency. The impedance printed on the product specifications is only the rated impedance given by the manufacturer, or the average value. In fact, the impedance in the entire frequency domain can be depicted as a continuously changing curve , Observe this curve to clearly understand the change 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. There are very few speakers. Some European products tend to have this characteristic, and the sound is relatively simple, and people who are accustomed to American voices will find it dull and tasteless.
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. If the two speakers have different split points, even if the others are the same, the sound will be different. The designer can adjust the timbre with different crossover points to control the timbre to achieve his ideal effect.
These issues should be considered before choosing a speaker. The size of the room and the environment, the matching with the power amplifier, and even the shape have become the focus of choice.
British sound, European sound, American sound ...
As far as the current Hi-Fi sound system is concerned, the speaker is still a relatively weak link in technology. 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. In general, most American speakers are strong and magnificent, suitable for replaying popular music; most British speakers are soft and delicate, very musical, suitable for replaying classical music; Denmark, Germany, France and other European speakers, The majority is between the first 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. The general description of these sounds is that the British sound is pure and warm, the sound is low, and the music is rich. The east coast of the United States is close to the British sound. 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.
Loudspeaker manufacturers must cater to the hobbies and tastes of Hi-Fi fans. Some manufacturers specialize in making loudspeakers with British sounds or East Coast sounds of the United States, and they are sold 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 music. As for frequency response balance, some manufacturers even deliberately create a frequency response curve that sounds exciting enough or add some harmonic distortion to please consumers. Rock and pop music fans do not calculate the purity and accuracy of 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. It seems to be the same as the speakers of the East Coast of the United States. Powerful bass, high sound pressure and crisp tone.
The main performance indicators of the speaker
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. Frequency response (unit: decibel dB): refers to the connection of a constant voltage output audio signal to the speaker system. When the frequency of the audio signal is changed, the sound pressure generated by the speaker increases or decreases with the frequency and phase The phenomenon that the hysteresis changes with frequency, and the corresponding relationship between this sound pressure and phase and frequency is called the frequency response. The curve of sound pressure with frequency is called "amplitude-frequency characteristic", and the curve of phase lag with frequency is called "phase-frequency characteristic". The combination of the two is called "frequency response" or "frequency characteristic". The amount of change is expressed in decibels. This indicator is an important indicator for evaluating the quality of the speaker. The smaller the decibel value, the flatter the frequency response curve of the speaker and the lower 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. For example, a speaker with good directivity is like a fluorescent lamp, and the light can be evenly distributed to every corner of the room. Otherwise, it is like a flashlight.
4. Maximum output sound pressure level: It indicates the maximum sound level index that the speaker can give when inputting the maximum power.
5. Distortion (expressed as a percentage)
Harmonic distortion refers to adding higher harmonic components that are not in the original signal to the reproduced sound.
Intermodulation distortion, we know that the speaker is a nonlinear device. During the process of replaying the sound source, due to the non-uniformity of the magnetic field of the magnetic gap and the nonlinear deformation factors of the support system, a new frequency that is not in the original signal will be generated. Component, so when the new frequency signal is added to the speaker together with the original frequency signal, it will be modulated to produce another new frequency. In addition, the music signal is not a single-tone sine wave signal, but a multi-tone signal. When two signals with different frequencies are input to the speaker at the same time, due to the large non-linear factors, the two signals will be modulated to produce a new frequency signal. Therefore, in the playback frequency of the speaker, in addition to the original signal, there are 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 the speaker has a certain mass inertia, the paper cone vibration can not keep up with the instantaneously changing electrical signal, which causes the transmission waveform to be distorted by the reproduced sound, resulting in changes in the spectrum and timbre. 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 refers to the input of a frontier sine wave signal to the speaker within the rated frequency range, the signal duration is 1 hour, the speaker does not produce the maximum sinusoidal power of thermal damage and mechanical damage.
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 a music signal, the amplitude of the audio signal changes greatly, and sometimes the peak value of the music power may exceed several times the rated power in a short time. The power labeling standards formulated by China's national standard GB9396-88 include maximum noise power, long-term maximum power, short-term maximum power, and rated sine wave power. Speaker manufacturers usually use the long-term power or rated power as the marked power of the speaker.
7. Nominal impedance (unit: ohm Ω): refers to the ratio of the signal voltage U and the signal current input by the speaker (this is the same as in high school physics, 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. The preferred values ​​of the speaker impedance specified by our national standards are 4Ω, 8Ω, 16Ω (recommended by the international standard is 8Ω), and the nominal impedance of the speaker is: the minimum value of the speaker resonance frequency peak F0 to the second resonance peak F1 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. Efficiency (expressed as a percentage): The definition of speaker efficiency is the ratio of the sound power output by the speaker to the input electric power (that is, the percentage of sound-electric conversion). 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 wrong labeling method has caused some consumers to confuse the two indicators of sensitivity and efficiency. 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. The sound waves radiated by their high and low frequency units are integrated, and the radiation pattern is roughly spherical, so the sound radiation of small speakers is closer to the ideal "point" sound 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 Speaker. The brands of such speakers include DYNAUDIO AcousTIcs, Morel, ATC, Lynnfield and Ensemble.
Pay attention to the following points before buying speakers
1. In addition to budgeting well, you must be well prepared. 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, make sure you have a good idea of ​​the nature of your audio, so that the choice of speakers will be targeted.
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. 
![[组图]什么是PN结åŠåŠå¯¼ä½“基础知识](http://i.bosscdn.com/blog/20/06/41/523030155.gif)
![[组图]第一讲 天线的基础知识](http://i.bosscdn.com/blog/20/06/41/5211340204.gif)
'+ data.username +'
'+ data.username +'
'; dom + ='
'; $ (' # follow_list '). append (follow_user);} if (data.status == "failed") {alert (data.msg);}});} else {// Unfollow if ($ ( this) .attr ('id') == 'cancelFollow') {$ .post ('/ d / user / cancelFollow', {tuid: article_user_id}, function (data) {// Data format returned: if (data .status == "successed") {follow_wrap.html ('Follow'). attr ('id', 'follow'). css ('background', '# f90'); $ (". followNum strong"). html (-getFollowNum); $ ('# follow_list .face'). each (function () {var target_uid = $ (this) .attr ('data-uid'); if (target_uid == now_uid) {$ ( this) .remove ();}})} if (data.status == "failed") {alert (data.msg);}}); return false;}}});});}); / * var myface = "{$ _super ['uid'] | avatar}"; var myname = "{$ _super ['username']}"; var article_id = {$ article ['id']}; var article_user_id = {$ article ['mid']}; // Article author ID $ (function () {<notempty name = "clearnum"> // Reduce the number of reminders var count = parseInt ($ ("# noticeCount"). html ()); count = count-{$ clearnum}; $ ("# noticeCount"). html (count); if ( count
Basic knowledge of speakers
Interesting and informative information and technical dry goods
Create your own personal electronic circle
Lock the latest course activities and technical live broadcast
comment
Publish
QSFP28 Optical Module Topic: Introduce the basic knowledge and types of QSFP28 optical modules
Published on 2018-03-15 14:20 • 106 times read
Labview basics
Published on 2018-03-08 17:56 • 581 times read
ARM basics
Published on 2018-01-25 02:23 • 840 views
Popularization of basic audio knowledge
Published on 16:36 2012-11-06 • 28451 times read
Briefly introduce the relevant basic knowledge of LTE test technology
Posted at 2012-07-17 10:35 • 586 views
Data communication basic knowledge summary
Posted at 2012-07-03 15:51 • 1233 times read
Some basic knowledge of data collection
Posted at 2012-06-14 10:34 • 2312 views
Principles and basic knowledge of touch screen
Published in 16:47 2012-06-13 • 1190 times read
Design guide for floating measurement and isolated input oscilloscope
Posted at 2012-03-27 17:13 • 2318 views
Detailed explanation of sensor basic knowledge (1)
Posted at 2012-03-20 10:30 • 22843 views
100 Questions about Basic Knowledge of Oscilloscope (Part 1)
Posted at 2012-03-16 11:52 • 15305 views
Basic knowledge of LCD
Posted at 2011-04-03 23:38 • 8320 views
Basic knowledge of lightning protection components
Published on 08:36 2011-01-15 • 7250 views
PoC basics
Published on 2010-01-11 10:39 • 784 views
Hard drive basics
Posted at 2009-12-25 15:38 • 466 times read
Basic knowledge of microwave circuit and design
Posted at 2009-08-24 01:45 • 25041 views
Basic knowledge of digital camera repair
Published on 2008-10-17 17:27 • 310 views
Basic knowledge of display maintenance
Posted at 2006-04-17 22:51 • 247 views
SMT basics
Published on 2006-04-17 20:47 • 1515 views
Basic knowledge of single chip microcomputer
Published on 2006-04-17 19:57 • 819 times read
Basic knowledge of components
Posted at 2006-04-16 23:47 • 281 views
Basic knowledge of capacitors
Posted at 2006-04-16 23:47 • 1618 views
Basic knowledge of circuit diagrams
Posted at 2006-04-16 23:33 • 8307 views
Basic knowledge of electronic technology
Posted at 2006-04-16 23:33 • 30676 views
Basic knowledge of remote control circuit
Posted at 2006-04-16 22:40 • 365 times read
Basic knowledge of hardware engineers
å‘表于 2006-04-16 22:19 • 1543次阅读
å°åˆ¶æ¿åŸºç¡€çŸ¥è¯†
å‘表于 2006-04-16 21:55 • 151次阅读
软æ¿åŸºç¡€çŸ¥è¯†
å‘表于 2006-04-16 21:13 • 173次阅读
PCB设计基础知识
å‘表于 2006-04-16 20:22 • 237次阅读
æ— çº¿ç”µåŸºç¡€çŸ¥è¯†
å‘表于 2006-04-16 19:03 • 4207次阅读
[组图]什么是PN结åŠåŠå¯¼ä½“基础知识
å‘表于 2006-04-15 23:00 • 1040次阅读
[组图]第一讲 天线的基础知识
å‘表于 2006-04-15 21:13 • 253次阅读