In the entire audio (including computer multimedia speakers) system, the speaker as a replay tool for the sound system, it is the simplest, but the most complex equipment. Because it is responsible for the electro-acoustic conversion equipment, the playback effect is directly related to the quality of the entire system, so whether the speaker selection is appropriate is an important factor in determining whether a sound system can be matched and formed successfully. To determine the pros and cons of a pair of speakers, usually from the technical indicators and people's subjective listening and evaluation of the two aspects, the author at the intermediate level of this brief introduction, for the majority of friends in the formation of their own sound system reference.
First, the main technical indicators of Hi-Fi speakers
The International Electrotechnical Commission (IEC) has set a minimum standard for household Hi-Fi speakers. The standard file is coded as IEC-581-7. We only need to look at the specifications of the speaker to see if its technical parameters reach this point. The minimum standard can be more objective to determine whether the speaker is qualified. Some minimum standards for IEC-581-7 for home Hi-Fi speakers are:
(1) Frequency characteristics: when the frequency is between 50Hz and 12500Hz, the deviation is within +4~8dB; in the frequency band of 100Hz~8kHz, the deviation is ≤±4dB;
(2) Pointing characteristics: ±30?o in the horizontal plane and ±10?o in the vertical plane, and the deviation of the frequency response curve from the positive axis is ≤±4 dB;
(3) Inconsistency of left and right channel speakers: the difference between the average sound pressures in the range of 250 Hz to 1 kHz is ≥ 2 dB;
(4) Total harmonic distortion number: ≤ 2% at 250 Hz to 1 kHz, ≤ 1% - 2% at 1 Hz to 2 kHz, ≤ 1% at 2 kHz to 6.3 kHz;
(5) Impedance: in the range of 20 Hz to 20 kHz, ≥ 80% of the rated impedance;
(6) Allowable power: ≥10W.
From the above standards, it is not difficult to see that the technical requirements of IEC Hi-Fi (high-fidelity) speakers are not very high, and the speakers produced by regular manufacturers on the market can basically meet or exceed these standards. So in this many qualified products, how to determine whether a pair of speakers is excellent from the technical indicators? I think the speaker is excellent? I think the speaker is mainly looking at the frequency response range, pointing characteristics, sensitivity, withstand power and impedance. Several indicators.
The frequency response range refers to the range in which the speaker can replay the sound frequency band, which is generally expressed in Hz to kHz. Since the limits of the human ear to frequency audibility are 20 Hz to 20 kHz, as the age increases, the hearing of the human ear will drop to about 25 Hz to 16 kHz. Therefore, as a pair of excellent speakers, the frequency response range must of course reach or exceed this range.
The pointing characteristic indicates the change in the output sound pressure level when the speaker deviates from the frontal axis, which has a large influence on the sound field width and positioning. However, the directivity of the speaker (mainly the medium and high frequency unit) is not as wide as possible, and the professional products have certain requirements. The well-designed unit (mainly the horn type) can be controlled in the specified range, and the sound pressure level drops less than 6dB. The general dome and cone units do not, and their directivity gradually narrows as the frequency increases. To point to the characteristics meet the requirements, the requirements for the unit used are: if the distance is less than 4 dB in the direction of 30?o from the positive axis, the frequency difference f and the equivalent radius a of the cone must satisfy f≤ 140/a, such as a 200mm (8-inch) speaker, the crossover point must be below 1650. Of course, some well-designed speaker units can also set the crossover point higher than the theoretical value, but whether it is low, medium or high frequency speakers, the caliber, crossover point and power should be considered when selecting ( Two-way frequency is especially important. Many of the two-way speakers only take into account the power capacity of the tweeter when dividing the frequency, and the crossover point is very high, ignoring the directivity requirement. This system is often only in the front of the speaker. It has a good frequency response, and after deviating from the axis, the frequency response is worse, affecting the width and positioning of the sound field.
Sensitivity refers to the efficiency of the speaker's electroacoustic conversion. It is usually expressed in terms of sound pressure dB/W/m or dB (decibel). The meaning of this indicator is to point to the speaker input 1 watt of power, on the positive axis 1 meter away from the speaker. The magnitude of the sound pressure obtained. Hi-Fi playback requires a maximum output impedance of 110dB, which requires the speaker to have higher sensitivity and a certain power margin, preferably greater than 88dB, so that there are at least two advantages, first: the amplifier And the power capacity requirements of the speaker are reduced, and the cost of both is reduced (the sensitivity is 88dB to reach the output 110dB sound pressure level, there must be 160W input power, and for every 3dB increase in sensitivity, the power required to reach 110dB sound pressure level will drop by one. Double); second: can reduce distortion. Low sensitivity is required to achieve the same sound pressure level as the high sensitivity output, requiring more power and amplitude, but this will increase the nonlinear distortion and reduce the life of the speaker. Relatively speaking, the better speaker sensitivity is above 86dB. At this time, they will not have any problem with the amplifier with rated output power of only 50W, but it is not that the speakers with low sensitivity are not good, like some classic Hi in foreign countries. -End speakers, such as the LS 3/5A and ATC SCM-20, are less than 85dB sensitive. Therefore, as far as this indicator is concerned, of course, the bigger the better. Because the speaker with high sensitivity inputs the same power, the sound pressure obtained will be larger than that of the speaker with lower sensitivity. Conversely, in the case of the same sound pressure, it requires less power than the speaker with lower sensitivity. small. Therefore, sensitivity is an important technical indicator for evaluating whether a pair of speakers is easy to push.
Withstand power is the amount of power that the speaker can withstand without causing excessive distortion. If the input exceeds the rated power (RNS) continuously to the speaker, the speaker will not only be distorted, but also be burned. Therefore, the larger the indicator, the better, but in practical applications, the chance of burning the RMS to 100W speaker is equal to zero, because the human ear can't bear the sound pressure it brings before it reaches this indicator. In multi-way crossover speakers, the chances of being easily burned are greatly reduced. Therefore, when purchasing a speaker, in addition to paying attention to the power of the speaker, you should also pay attention to what kind of material and structure the tweeter uses.
Impedance is the resistance of the speaker to alternating current. It consists of three parts: resistance, capacitive reactance and inductive reactance. It is the reference value for calculating the power supplied by the amplifier. Since the impedance of the speaker changes with frequency, the value that the manufacturer gives to the speaker is actually an average value. This is also a concern when using speakers. The impedance of common home speakers is generally 8 ohms, 6 ohms and 4 ohms. The impedance of modern speakers has a tendency to develop small, and the impedance of the speaker becomes smaller. The advantage is that more energy can be obtained from the amplifier, which means that the impedance is small when the input power and sensitivity are not much different. The sound of the speaker will be louder than that of the louder speaker. • When paired with a pair of speakers and an amplifier, there is minimal chance of matching problems (especially for transistor machines). However, when using an amplifier to push two pairs of speakers, it is necessary to avoid the two pairs of speakers inconsistent impedance (such as a pair of 8 ohms, a pair of 4 ohms) and the impedance of the two pairs of speakers are below 4 ohms, otherwise, It is easy to cause the amplifier to burn shortly. ? As for the consistency of the left and right channels, the specification is rarely marked. Empirically, most common products do not meet this requirement, but this indicator has a lot to do with the accurate reproduction of sound field and sound image localization. When we are shopping, it is best to buy some reputable brand products, preferably the products that have been paired with the left and right channels. Generally, such products are indicated on the production number of the speakers.
Second, the subjective (hearing) evaluation
To judge the quality of a pair of speakers, although a certain answer is obtained from the technical indicators, people buy speakers or other audio equipment only to get a good sound rather than a dry technical indicator, and a good technical indicator does not mean With a good voice, as the CD appeared, no one can deny that it far exceeds the LP turntable in terms of technical indicators. However, due to the shortcomings of the early CD player, the sound is hard, sharp, and not musical, it has attracted many people's accusations. In the case of the speaker, there are also such problems, such as the famous LS3/5A, which has a sensitivity of only 82dB and an impedance of 11 ohms. In terms of technical specifications, it is a pair of very inefficient speakers, but It is the most famous monitor speaker in history, and it has been widely welcomed because of its extraordinary presence in vocals and strings. From the above examples, we can see that the evaluation of audio equipment, relying on technical indicators to judge its pros and cons is also one-sided, plus people have different preferences for audio and sound, so in the purchase of speakers, especially some have When it comes to good products, it seems that it has become more important to be able to satisfy yourself.
An important aspect of the subjective listening evaluation of the speaker is the ability to reproduce the accuracy of the original sound. The strict definition of accuracy is that under certain price and speaker size constraints, the sound details, dynamic range and enveloping sound of the original sound recording should be reproduced in the widest possible frequency range, even if there is a difference.
In order to ensure the accuracy of the results of the evaluation, we must seize every opportunity to listen to and compare the sound difference of different speakers. At the same time, we should try to use high-quality amplifiers and high-level audio equipment, and put different speakers at the same volume. Under the same position, listen to the comments to reduce the factors of change during the evaluation. Since the software theme used has a great influence on the results of the evaluation, when selecting the music recording of the demonstration, it should not only focus on how beautiful the music itself is, but also pay attention to its recording accuracy and its outstanding sound quality. Some aspects of the requirements.
In the subjective listening evaluation, there are roughly the following four criteria:
1, tone uniformity Voice uniformity is the most important speaker in the evaluation. The speaker should have a uniform and true tone expression throughout the frequency range from bass to treble. The overall assessment of the entire range is generally carried out in four segments:
A. Irregularity of the bass/mid range. The best way to explain this is to pay attention to whether the bass performance is humming or weak, or whether there is a boring sound.
B. The fluency of the vocal range. Vocals include the voice of speech and the singing of actors. When listening to comments, you should pay attention to whether there is IF coloring. This is a weak point that the speaker is easy to have. The performance is that the tone is not constant, the sound quality of the person is deteriorated, and the sound is emitted with a serious nasal sound, a squeak or a rough squeak, a hollow sound, and the like.
C. The fluency of the high range (frequency band around 2500 Hz to 13 kHz). You should choose the string part of the large orchestral team to listen to the comments, and pay attention to whether there are unnatural things in the string sound or where the sound is dry or excessively sticky. Those who can do the correct participation in this frequency band have higher quality requirements, and they are required to have a very good listening ability for the live string performance. It is best to ask some experienced fans to help.
D. Performance of the high-pitched area (band above 13 kHz). Pay attention to the sound effects of jazz or rock-and-roll. The tested CD should contain clear, repeated playing transients. Be careful to listen carefully to the expression of each speaker. There are no blurred features, hum and a rustling sound. Rather than a crisp metal tone, these indicate uneven defects in the timbre surface of the high-pitched area.
2. Dynamic Range Almost all speakers will compress the dynamic range of the source. The obvious form of dynamic range limitation is to produce audible distortion, such as frequency domain imbalance, high and low frequency disconnection. Usually the bass and midrange are humming, humming or bursting sounds that are too loud. Dynamic Range Another hard-to-find restricted form is the nonlinear response, which is manifested by the large volume of the output. The mid-to-high range is more powerful than the low-frequency output. . Due to the rumble of the woofer, it is not certain that the speaker distortion is caused by the vibration of furniture, floor or window. It is also not certain that the sound enhancement phenomenon is caused by the speaker or the distortion naturally generated by the human ear at very high volume. This can be determined by repeating the review for a long time in a very familiar listening environment.
3, bass expansion ability Very few speakers can really reproduce the frequency as low as 20Hz or 25Hz, the energy of the recording content is concentrated in the frequency band below 40Hz is also very rare. The use of large bass drums in classical music and subwoofer synthesizers in popular music is the best source for judging bass expansion. However, if you are not listening to the actual environment at home, it is difficult to determine the subwoofer responsiveness of the speaker. Because the placement of the speakers and the acoustic characteristics of the room have a much greater impact on the bass performance of the speakers than on the characteristics of the speakers themselves. Considering the above situation, you can listen to the bass expansion capability of the speaker with one or several very familiar recordings. The content should include a percussion instrument with a fairly dynamic range, a music judgment speaker that makes the subwoofer recording effect easy to feel. The sound quality of the low frequency band.
4. Sound image localization ability Sound image localization refers to the position and depth of sound on the space stage. Sound image localization ability is the most varied and difficult to grasp for listening to the speaker.
Listening to comments, attention should be paid to the stability of sound image localization. For example, the position of the band actor is erratic as the frequency of the music increases or decreases. Can the sound stage fill the space between the two speakers or extend beyond the distance between the speakers? Can it be only in the middle of the two speakers? Is the depth of the front and rear of the instrument and the human voice naturally unfolded? Is it excessive? Exaggerated reverb phenomenon?
Different types of speakers have different inherent sound image localization characteristics. For example, dipoles and most electrostatic and planar pole-type speakers usually create increased depth and space at the expense of; ordinary speakers are somewhere in between. After understanding the above-mentioned points of listening, it is also necessary to note that speakers produced in different countries also exhibit different sound characteristics due to local human factors. In theory, an ideally designed speaker should be suitable for a variety of genre music, faithfully replay the original sound, no increase or decrease in signal components, but less speakers that can achieve neutral sound. At the same time, in theory, the frequency response curve of the speaker is flatter and better, but in fact, the sound of a speaker with a flat frequency response is not necessarily pleasant. Most of the speakers have undulations in some frequency bands, and different speaker curves are different. This also forms the style of the sound.
For example, the professional audio produced in the United States generally has lively, heroic and hearty sound characteristics. The American sound is divided into East Coast Sound and West Coast Sound. The East Coast sound is represented by AR, THIEL, AVALON, Hales, Cello and Boston. Brands, such speakers generally pay more attention to the accurate reproduction of sound, showing a tendency to play orthodox music, and can create a deep, wide sound field, the overall sound and the British sound are somewhat similar, but the sound More energetic and more analytical, these brands have become the new representative of American speakers. The speakers produced by JBL and Alter are the representatives of the West Coast sound. Due to the influence of Hollywood, the sound of these speakers is particularly hearty, bright and extremely strong. When listening, they often give people a strong sense of stimuli and their sales targets. Mainly for those who like rock, jazz and pop music, the sound of West Coast speakers has been on the east coast in recent years. Most of the British equipment generally has the characteristics of sweet, warm, low-pitched and musical, and it should be said that this is a sound that is very suitable for listening to classical music. Since most of the British speakers are manufactured in accordance with the BBC standards, they are also guaranteed in quality. In addition, small bookshelf speakers are also a product that the British are very good at, such as ProAc, Rogers, ATC, AE, KEF, B&W, Tannoy, Mission and other famous brands. In the past two years, the European voice has been dubbed as “there are thousands of stylesâ€. The European sound can be divided into two parts: Nordic and Southern Europe. The Nordic products are mostly influenced by French products, and the sound exudes a fresh and beautiful romance unique to the French. At the same time, it also has its own unique features in the portrayal of musical details. The more representative brands are LMLab, Dali and so on. The products of Southern Europe are represented by Italy. The sound is characterized by enthusiasm and charm, and the sense of quantity is sufficient to represent the famous Sonus faber. The speakers of Germany, Sweden and Denmark have a sound characteristic of correctness and less dyeing. The representative products are Dynaudio. , Jamo, etc.
Most of the early Japanese speakers emulated the products of the West Coast of the United States. They mostly emphasized the contrast between high and low frequencies. They felt very exciting when they first heard, but listening for a long time is easy to make people tired. With the continuous advancement of Japanese speaker manufacturing technology and the changes in the world audio market, some small and medium-sized speakers in Japan such as Victor, JVC's SX-V1, SX-V7, Pioneer's S-LH5 and Diat one's DS- A5 and so on are both good in performance and price ratio, and the sound is gradually shifting to the direction of high analytical power, abundant energy and accurate reproduction of sound characteristics.
Frame For Iphone X,Metal Frame For Iphone X,Frame With Glue,Original Metal Frame For Iphone X
Shenzhen Xiangying touch photoelectric co., ltd. , https://www.starstpmobile.com