Get out of the misunderstanding of speakers

In the sound system, the structure of the speaker is the simplest, but the role it plays is the most important. The sound box is the final link in the sound system, and it is the key part to convert the electrical signal into the sound signal. Because there are not many structural components of the speaker, it leads to any deficiency and affects the entire replay effect. Evaluation of the speakers, but also based on subjective listening - final replay music is good or bad as a standard. Therefore, the following first problem also arises: This is the unified problem of the technical testing of speakers and the evaluation of subjective sound quality.
1. Friends who have certain HiFi experience in speaker measurement and listening will have such a consensus: This is the gap between the speaker's technical indicators and subjective audition.
Why is this happening? This is to start from the beginning, from the main technical indicators of the current speaker test.
Among the technical indicators of speakers, the most important ones are the following: this is the frequency range, withstand power, sensitivity and phase characteristics, and transient characteristics.
Frequency range, also known as frequency response, refers to the range of replay from low to high in the speaker. At some point, a pair of small speakers and a pair of large civilian monitors marked frequency range may be consistent; but the feeling at the time subjective listening very different. Why is this? Is the test inaccurate or someone deliberately made a fake? Under normal circumstances, the above speculation is wrong, but there are other reasons.
Reason 1: The distance between the current test standard and the actual application. The current frequency response test standard still uses the 1 watt · meter standard many years ago. When the audio test standard was formulated many years ago, the frequency response curve of the speaker under 1 watt and 1 meter, in many cases, represents the full power test, which is close to the actual situation in use. The speakers of that era were basically of low power and high sensitivity. For the input power of 1W, it basically represents the actual working state of the low-power speaker. In recent years, with the development of manufacturing technology of speakers, the vast majority of speakers have high-power, low sensitivity of the. This makes the gap between the current frequency response test and the actual use more and more. At present, most of the speakers, mainly refers to home speakers, they are subjected to power in excess of 50W, and some even up to 200W. The sensitivity, can only achieve 82 ~ 86dB.
In this case still uses 1 watt meter frequency response test, test and use cases will produce inconsistent. The input of a 1W test signal is only equivalent to 1/50 to 1/200 of the power of most speakers, and the actual power of these speakers is generally 15 to 50W, and it will even reach full power at peak, which leads to a test Problems that deviate from reality.
An accurate and feasible measurement methods, are supposed to try to simulate actual working conditions of test equipment, then the test result was the most effective.
Therefore, when the speaker frequency response test, if they can add a half-power frequency response test, that this half-power frequency response curve will have a real impact on the actual work most speakers.
For example, a small speaker nominally 200W, when using a 100W half-power test signal to test it, you will see its serious deterioration in low frequency and a large increase in distortion.
Why is this the case? This is because the woofer unit is restricted by the equivalent volume of the speaker and the influence of factors such as the inverter tube, and the resonance of the cabinet itself increases, which will inevitably produce the above results.
Testing the speakers with a low-power signal of 1W is only equivalent to a vocal sing opera that has not been professionally trained. It is not the actual working state, and the real actual working state is to sing loudly on the stage, so the good voice of the small voice and the performance on the stage are completely It is a different concept, two different things.
Therefore, the increase of modern speaker frequency response test at half power, not only has a very real significance, and has the effect of counterfeiting - the nominal 2000W can make those little speakers completely exposed the true colors.
Reason 2: The current test standards are too loose. The subjective listening and frequency response tests are not uniform. There is another reason. This is that the current test indicators are too loose and not strict enough.
The current speaker frequency response test is based on -3 dB. In other words, based on a final frequency as measured at the high end and low end of the sound emitted by the attenuation half.
For the production technology of the tweeter unit that is constantly developing and mature today, it is no problem for a mid-range or higher tweeter to produce a 20 kHz tweeter. Currently the world's most advanced high-frequency soft dome tweeter silk film has reached the upper limit of 40 kHz and a high frequency tweeter metal film has reached 80 kHz. Plus tweeter less affected by the speaker cabinet, so the new speaker more than the current mid-range, high-frequency side without problems. The greater impact on high-frequency replay is limited to the selection of the low-end crossover point of the tweeter unit, whether the connection with the midrange unit is excellent, and whether there is sufficient power margin.
The situation is much more complicated for the woofer. Although the manufacturing technology of the woofer has also made great progress, especially the new diaphragm materials are constantly coming out, the technical indicators of the woofer are already good. But woofer test indicators, the gap between it and the actual index after the speaker is mounted on the obvious. Sometimes, an excellent woofer is installed on a sound box with a lot of problems, which will completely lose its original advantages.
For example, a poorly-designed cabinet will produce severe mid-to-low frequency resonance. This resonance will not only cause sound staining when the speaker is replayed, but also cause deterioration of the test curve.
Speaking of the pros and cons of the low-frequency test curve, I mentioned that the current test standards are too loose and not strict enough.
As shown in FIG. 2a and 2b two frequency response curve shown, can be measured as the final 30Hz, but very different replay bass performance. Why is there a clear difference on the curve and the result after the measurement and interpretation is the same, this is because the standard of -3dB as the interpretation is too loose. If the measurement standard is -2dB or -1dB, then the measurement results of the two curves are very different.
It is generally believed that an audio frequency response with an attenuation within -3dB is an effective frequency response. Too attenuated, which, when replayed the role was basically overwhelmed, ineffective. However, a lot of practice has proved that the human ear after rigorous training can achieve a very high resolution and accuracy. The human ear can clearly distinguish the difference in replay tone caused by the difference of a few dB. Therefore, if the speaker is tested for frequency response, in addition to the standard result of -3dB, it can also provide a test result of -1dB, which will provide a more practical reference for the speaker.
The test indicators of large monitor speakers are more "quasi". In fact, the word "quasi" here does not mean correct, but means that the test indicators are closer to the subjective listening. Since the above mentioned that the current test method of 1 watt · 1 meter has deficiencies, then within the scope of the current test standard, which speakers have the closest technical test to the subjective listening results? The answer is as follows: this is a large monitor Speakers and large civilian speakers with better quality.
Why the result will be a large speaker? There are three reasons. One is that the volume of the large speaker cabinet is large, so the low frequency response in actual work is limited by the volume of the cabinet. The second is a large speaker power handling large power margin is larger, reached at work the possibility of overload distortion is relatively small. Especially large monitors, the remaining power reserve is very large, it did not produce the possibility of overload distortion. The third is a large woofer speaker diameter is relatively large, when the same is generated bass, a small stroke of the unit, it is relatively small distortion.
Second, the argument regarding specific errors speaker voice coil 1 large enough accurate long trip often heard someone mention a large voice coil long stroke he said. The so-called large voice coil means that the diameter of the voice coil is relatively large, which is easy to understand. But long trips are a different matter. Because long travel is just a relative concept, under the pre-comparison of real comparability, the larger the voice coil, the shorter the travel can be and the longer it is impossible.
It can be seen from Fig. 3a and Fig. 3b that the large voice coil has a short stroke. There are two key factors that determine the length of the woofer's travel. A speaker cone paper is glued to the outer fold rings (mostly rubber, foam and fabric after treatment is made) is wide enough, has enough elastic range. Theoretically, the ring off the wider, the stronger the elasticity, the longer the stroke obtained. But it can not be too large off ring, the elastic can not be too strong. Off ring is too large, it would reduce the effective area of ​​the drive unit. If a 6.5-inch woofer is too large, it can only function as a 5-inch woofer. There is no longer a small-diameter unit with a long stroke, and it is impossible to emit a low frequency with a sufficiently low frequency and practicality.
Another factor in determining the stroke woofer speaker cone is affixed to the bottom of the fixed core support plate. Because the speaker paper cone can be reliably moved back and forth only through the two points of the folding ring and the fixed core support piece. A fixed core support plate plus rubber cotton fibers, a synthetic material. The elastic range of the fixed core piece is limited. Therefore, it is not the rubber folding ring that restricts the travel of the woofer, but the fixed core support piece. Since the diameter of the fixed core support piece cannot be made large, it will never reach or exceed the diameter of the rubber fold ring, so the larger the diameter of the voice coil, and the diameter of the fixed core support piece is limited, leaving the fixed core support piece The smaller the range of motion, in other words, the smaller the travel of the speaker. Only when the voice coil is small, the movable range of the fixed core support is relatively wide. Therefore, the large voice coil and long-stroke woofer are only a relatively speaking statement, and are not accurate.
2. Long-stroke small-caliber woofer cannot replace large-caliber woofer. It is often said that small-caliber long-stroke woofer can produce enough bass as long as the stroke is long enough. This is a wrong view. In theory, as long as the same volume of air is driven in the same unit time, the same level of sound pressure can be generated. But as far as the woofer is concerned, this is unrealistic. Because of excessive travel and excessive air compression ratio, the replayed sound will be seriously distorted. For a large-diameter woofer (diameter above 200mm), when sufficient sound pressure is reached, the driving area of ​​the speaker cone is large and the stroke is short, the distortion during replay is small, and the sound is good. Even in a more ideal state, the current speaker sound distortion can only achieve 1%. When working with a small-diameter, long-stroke woofer, the distortion increases rapidly due to the excessive stroke, which is an illusion that the quantity is not guaranteed. So for most small and small-caliber speakers, even the low-power test low-frequency of the speakers is OK, but in actual use compared with large-diameter speakers, the gap is still quite large, it is an essential difference. So in the conditional when large selection of speakers is justified.
3. The sound of low-sensitivity speakers is different. There was a time when such a saying was popular, that is, the sound of low-sensitivity speakers is good. In fact, this is just a one-sided and unscientific statement.
The main factors that determine the sound quality of the speaker are only frequency response, transient characteristics, damping characteristics and withstand power. It has nothing to do with sensitivity. In other words, for the same power receiving speaker, the replay at the same volume, the lower the sensitivity of the speaker, the larger the input power required, the closer overload, distortion is relatively increased.
Twenty years ago, due to the technical quality of the speaker unit itself has not reached a relatively good level. When making speakers, a lot of attenuation correction circuits can only be added to the crossover. The final result is that the frequency response curve is straight, but the sensitivity is greatly reduced, only reaching about 82dB. In this case, usually use high-power amplifier to drive low sensitivity to better speakers, but driven by high-power, low sensitivity for small speakers are prone to overload distortion, can not even play some great dynamic musical work.
Due to the development of audio technology, there are currently a variety of models with monitor levels of over 100dB and Hi-Fi speakers, and the highest sensitivity is close to 110dB.
4. A sound-absorbing cotton speaker does not represent the quality grade of "no sound-absorbing cotton speaker speakers is low", this statement is not accurate.
There is no sound-absorbing material in the low-end speakers, which is a reality.
In packaged machines and cheap finished speakers, basically no sound-absorbing material is filled. Therefore, some people have come to the conclusion that there is no sound-absorbing cotton in low-end speakers, and adding filler materials to low-end speakers can improve the replay effect.
In fact, the above conclusion is no causal relationship, any associated inherently exist.
The sound absorbing material only plays two roles in the speaker, one is to eliminate some resonance and staining of the speaker box; the other is to appropriately reduce the volume of the speaker. It doesn't matter which grade the speaker belongs to.
Some people think that adding fillers to the speakers is a panacea, which is wrong.
First, the box design is reasonable as long as the speaker itself is no obvious resonance box big enough, can not add filler material can produce high-quality speakers. There are many examples of such success in the world of speaker production. No filler material is added to the speaker box, which is good for the transient characteristics of the speaker.
A speaker that has been carefully designed and carefully manufactured has basically reached a relatively ideal state when it leaves the factory. In this case arbitrarily change the fill material in the presence or absence of speakers, how many speakers will cause a lot of replay influence, but these effects are mostly negative.
Excessive filling will cause fat meat replay sound, the transient characteristic difference, weakly. Although the curve will be improved during the test, the sound performance will deteriorate when subjectively listening. One thing must be clear, this is that the speaker is listening, not watching.
The frequency divider in the frequency divider of the speaker on the speaker, the main components of only three categories: This is the coil inductance, capacitance and resistance.
The function of the resistor is an attenuator, which is used to balance the sound ratio of each frequency band. When selecting long as the power is large enough on the line. For the high-frequency attenuation resistance of small speakers, the resistance effect of the metal film will be better.
The role of the inductance is to filter out high-pitched sounds, strobe bass. Popular in recent years with a variety of shaped inductor enameled wire wound. Among them are stranded enameled wire, hexagonal enameled wire and ribbon enameled wire, etc. (Figure 4). Shaped wire of each inductor, are referred to as having a certain divine. But is this really the case? Actually not.
There are only three requirements for inductive coils for speakers. One is that the inductance value is accurate; one is that its own DC resistance is low; one is that it is not easy to produce saturation distortion.
Regarding the accuracy of the value, as long as the high-precision instruments are used to measure and calibrate one by one during the production process.
In order to reduce the self-resistance of the inductive coil, it is necessary to improve the conductivity of the enameled wire itself. The electrical conductivity of the enameled wire itself and their cross-sectional area are closely related to the cross-sectional shape. When the cross section of the wire is round, square, or hexagonal (Figure 5a, b), the efficiency is the highest.
Specific to the winding coil, hexagonal cross-section of the wire, can effectively reduce the gap between the turns, to improve the efficiency of the inductor. Especially for multilayer coils with a large number of turns, the improvement effect will be very obvious. However, when the hexagonal enameled wire is used, the production cost will also be greatly increased. Therefore, if it is not used in very high-end occasions, the use of round oxygen-free copper enameled wire with a purity of more than 4N will have a very good effect. When choosing the wire diameter of the enameled wire, there is no saying that the thicker the wire diameter, the better. As long as the inductance meets the requirements, its DC resistance is about one tenth of the DC resistance of the woofer voice coil. DC resistance of the inductor too, directly affects the damping characteristics of the low frequency speaker; DC resistance of the inductor is too small, the production cost will increase unnecessarily.
As for the selection of the crossover capacitor, there will never be a capacitor that will fundamentally change the replay of the speaker. For those who make their own speakers or want to improve the finished speakers, they must first have a clear purpose. When making a speaker, the grade of the crossover capacitor should be selected according to the investment of the speaker unit.
For example, if you buy a tweeter with dozens of yuan, it would be worthless to spend another 20 yuan on matching capacitors. You might as well buy a tweeter for one hundred yuan, and choose a crossover capacitor of a few yuan for one. If you have bought a 300 yuan a tweeter, spend hundreds of dollars to buy a crossover capacitors, which can be called good match.
For audio capacitors, different brands and different materials have different effects on replay. But these internal, delicate difference is more than a mid-range tweeter in order to get better reflected. For low frequency dividing capacitors, mainly accurate capacitance, voltage, based reliable. Treble frequency division with respect to the capacitance, the requirement can be relatively low, because high-grade large value of capacitance is too expensive. Often in a state of gains and losses after use.
6. The advantages and disadvantages of neodymium iron boron For the speaker unit, the magnetic material is their skeleton and the basis of their power. Selection of materials for producing high-energy product of the speaker units, the speaker is a good way to improve the sensitivity. But not the only way.
For the magnetic material of the speaker, especially the magnetic material of the high-power woofer, there is an important criterion that the thermal stability must be good. The magnetic energy product of NdFeB magnetic material is large. But it also has fatal injuries. First, it is easy to oxidize itself; second, its thermal stability is poor. NdFeB magnetic material Curie temperature is very low, at 80 ℃, the performance will drop to 80% of the reference temperature (reference temperature of 24 ℃). This illustrates such a problem: if it is a NdFeB woofer that has not been subjected to special heat dissipation treatment, when it is working at high power, due to the effect of temperature increase, it will cause insufficient bass. This variation of timbre is clearly noticeable to most music lovers.
Therefore, most of the current foreign speaker manufacturer, the NdFeB material as a magnetic material substantially tweeter, and to take more effective measures for heat dissipation. NdFeB magnetic materials are rarely applied to the manufacturing process of woofer.
HiFi After years of practice, most people basically can clearly distinguish small differences different audio replay of the sound signal line caused. Since the difference in thermal stability NdFeB frequency response variation caused by the woofer than 10%, it would be a big regret.
7. It is not advisable to use the demagnetization method to improve sound quality a while ago. It has been popular that the demagnetization method improves sound quality. The so-called demagnetization method refers to the adsorption of some large iron nails on the magnet of the speaker unit of the finished speaker. The magnetism of the unit itself is dispersed, which reduces the sensitivity of the speaker unit and changes the original Q value. Adjusting speaker using replay effect demagnetization process, it will play a role. However, the demagnetization method is only suitable for those speakers that originally sound dry and tight. It is impossible to apply to most occasions. For speakers that use the demagnetization method to improve the broadcast, the method of adjusting the sound absorption material in the speaker and adjusting the inverter tube of the speaker can also achieve the purpose, and the sensitivity of the speaker will not be lost.
8. The ideal frequency response curve due to the small speaker bass replay ability of small speakers speaker cabinet by most of the constraints, the gap between the frequency response curve and subjective listening test is also the largest, which is also on the small speaker frequency response curve proposed test There is a compromise and new requirements. This requirement is: the low end of the frequency response should not be too low for the effect of digitalization, and the extension of the low frequency end should not be deliberately pursued below 35Hz or more, because for small bookshelves that use small-caliber woofer (6.5 inches or less) Type speaker, its test frequency response below 40Hz is of little significance in practical applications. However, a graph (FIG. 6) if the lowest frequency of the frequency response test to 50Hz, the low end of the curve becomes a small peak and the high-end drop a little bit, it will not exceed the test standards premise, greatly Improve the sound effect during replay.
With the small speaker with the curve in Figure 6, when replaying music, you will feel that the bass is relatively full and powerful, and the replay sound is kind and sweet.
There are actually many misunderstandings about speakers, and it is impossible to make it clear in a text. With the development of science and technology, the old misunderstandings have come out and new ones will be encountered. Therefore, if you want to avoid detours, you have to be truly in line with international standards and keep learning. var check_allow = "/d/Api/iscantalk.html"; var add_url = '/ d / article / write /'; function CheckLogin () {now_uid = ''; var ElecfansApi_checklogin = '/ webapi / passport / checklogin'; var logout_url = "{: U ('Login / logout')}"; var logout_url = 'http://bbs.elecfans.com/member.php?mod=logging&action=logout&refer=front'; $ .get (ElecfansApi_checklogin, function (data, textStatus) {if (data! = "") {EchoLoginInfo (data); CheckEmailInfo (data); data = $ .parseJSON (data); now_uid = data.uid; / * var login_content = 'write an article