Main indicators of speakers and methods for evaluating speakers

Indicators of the speaker 1. Power This parameter is actually a basic parameter for measuring the performance of a multimedia speaker . It is only because the manufacturer intentionally avoids it. Therefore, in the description of many products, the power becomes a parameter that has no meaning.

The power of multimedia speakers is mainly as follows:

1. Rated Output Power (RMS): RMS power can be said to be the only truly meaningful of all power marking methods. It refers to the maximum power that the power amplifier circuit can continuously output within the rated distortion range. Also known as "effective power." The power we refer to in the previous discussion of the power amplifier circuit generally refers to the rated output power.

2. Music output power (MPO): refers to the instantaneous maximum output power of the power amplifier circuit when the distortion does not exceed the specified range.

3. Peak music output power (PMPO): refers to the instantaneous maximum output power of the power amplifier without considering the distortion at all.

The latter two kinds of power are actually meaningless, because their so-called "instant" is often a few milliseconds that cannot be heard at all. However, many manufacturers are eager to use their own product power to mark the big, often happy to use these two annotations, especially PMPO power. Most of the speakers on the market, such as hundreds of watts, are so, and even some speakers mark their power as 2000 watts!

This is really a joke! The real 2000 watt amplifier and speakers are enough for everyone in your community to hear the sound of your home music. The real 300 watt speaker is also noisy. The whole building is not peaceful. Is it a small desktop speaker? Can it be done? It is no wonder that PMPO power has been dubbed "JS power" by enthusiasts.

According to the general practice, the ratio between PMPO power and RMS power is generally 5-8:1, that is to say, the speaker with its own 300W is actually an ordinary speaker with an output power of about 30W!

Real brand-name manufacturers will not use PMPO power. If the product is really good, why should it use this method? Therefore, seeing the logo of PMPO at least indicates that manufacturers are not confident enough about this product.
In addition to the power amplifier section, the power parameters in the multimedia speaker also include the maximum power of the speaker and the maximum output power of the power supply. The smallest of these three parameters is the maximum output power of the speaker . Moreover, there is a certain relationship between these three parameters. For example, the RMS power must be less than the maximum power of the speaker, otherwise the speaker will be burned out. The maximum output power of the power supply must be at least 150% of the RMS power. The extra 50% is also the so-called "power reserve". Otherwise, the sound will be distorted when the volume is loud or large (there are a lot of speakers on the market). This problem exists).

Second, the frequency range and frequency response This is the two basic parameters to identify the sound reduction ability of the speaker , the former refers to the range between the minimum effective playback frequency of the speaker and the highest effective playback frequency, in Hertz (Hz); the latter refers to a When the audio signal outputted by the constant voltage is connected to the speaker system, the sound pressure generated by the speaker increases or decreases with frequency, and the phase changes with frequency. This sound pressure and phase are related to frequency. The change relationship is called the frequency response in decibels (dB).

In general, the frequency range of the multimedia speaker is more, the larger the range, of course, the better the effect. But the problem is that many products do not identify the "frequency range of the speaker ", but the "frequency range of the power amplifier circuit." This results in values ​​such as 20Hz-20KHz covering the human hearing range.
Of course, this is purely intentional and confusing! The minimum playback frequency of the speaker can be calculated. According to the relevant empirical formula, according to the usual reverse box design of the multimedia speaker , even if the 8" speaker is used, the bass that can be played back is only 62.6Hz, using 6" or 4". At this time, it is as high as 80Hz or even 100Hz. Under this frequency, its power will drop sharply. Although the speaker is still moving, there will be no sound heard, that is, "only see the bass move, do not smell the bass. The phenomenon of coming. Any sound that can be heard at this time is actually the noise generated by resonance!
In fact, the speaker that can really emit 20Hz sound, the price is probably enough for us to open a speaker manufacturer. Therefore, when we see the manufacturer labeled "20Hz-20KHz", we can send it a "go to XXX"...
Frequency response parameters are rarely available from manufacturers, probably because this parameter is difficult to replace with other "similar parameters". However, some of the big companies in the HI-FI industry, such as Swans, still provide this chart. The frequency response chart is similar to the sound card frequency response chart of the previous issue, and the smoother the better the effect. But it should be noted that the speaker is not a sound card. It is impossible to have a straight horizontal line like a sound card. Even a good speaker , its frequency response is also a curve with a large curvature. But it should be as smooth as possible, and there should be no special peaks or troughs in the middle (this means that there is a special strengthening or weakening in a certain frequency band). And should be as good as possible on the midrange end. You should not only consider the dive of the bass.

Third, the distortion degree Distortion is compared with the signal before amplification by the amplifier and the signal amplified by the amplifier, the difference between the ratio of the amplified signal and the original signal, we call the distortion. Its unit is a percentage. That is, the degree of "sounding" of the signal on the speaker . For multimedia speakers , it is not a bad thing to have a certain distortion, but in a reasonable range, in general, the distortion of multimedia speakers should not be greater than 1%, and the subwoofer is special, up to 5%.

Fourth, the signal to noise ratio I think there is nothing to explain, in general, the signal to noise ratio of multimedia speakers should be greater than 80DB, the subwoofer should be greater than 70DB. Only speakers with a signal-to-noise ratio greater than 90DB are eligible to call themselves “quasi-HI-FI speakers ”.

5. Sensitivity Sensitivity refers to the input signal that can generate full power output. The lower the input signal, the higher the sensitivity, and the unit is also decibel (DB). The sensitivity of the speakers is 3dB, and the sound pressure of the output is doubled. In general, multimedia speakers mostly refer to input signals that produce full-power output. The lower the input signal, the higher the sensitivity. The sensitivity of the speaker is 3dB, and the sound pressure of the output is doubled. The multimedia speakers are mostly high-sensitivity speakers above 90DB, because the power of the input source is very small. However, the improvement in sensitivity is at the expense of sound quality. The higher the sensitivity, the more distortion and noise can be heard. Therefore, some high-end multimedia speakers use a low-sensitivity design, but invisibly increase the requirements for audio equipment.

6. Impedance This concept is more complicated. Simply put, the sum of the resistance, inductance and capacitance of a circuit (resistance, inductive reactance, and capacitive reactance) is obtained by impedance, and the unit is the same as the resistance value, which is also ohm. The impedance identification in a speaker generally refers to its line input impedance. The input impedance of a typical multimedia speaker is between 4 ohms and 16 ohms, but it is also larger. For multimedia speakers , the higher the impedance, the better the sound quality of the speakers , but the harder it is to drive.

Above, we are talking about the main parameters of the speaker manual. Below, let's talk about how to evaluate and test the speakers .
Evaluating the terminology of a speaker : Transient: The ability of a sudden increase or decrease in sound. If the time required to increase/decrease to a certain sound pressure is less, the better the transient, the actual performance is that the sound is not mixed. ability.
Dynamic: The ratio of sound pressure or power to voltage at the minimum and maximum sound, quantified is the dynamic range.

Tone: The tendency of the sound, such as high-frequency clear or low-frequency male or sound. To a certain extent, the tone is not good or bad, depending on personal preference.
Sound field: The sum of the spatial relationships formed by the speakers with different sounds and their states.
Positioning: The fixed position of the three-dimensionally distributed pronunciation device presented in the sound playback space.
Air sensation: The degree of vibration of various sounds during sound reproduction.
Image: The ability to focus on the sound during playback.
Resolution: The ability of the sound to represent the details of the object.
Transparency: Whether the sound form is clear and easy to understand.
The sound is full: the proportion of high, medium and low sounds of the replay sound is appropriate, the treble is moderate, the midrange is sufficient, and it sounds a certain elasticity.
Level: The level of sound means that the replay sound can truly reflect the overall sense of a band.
Clear: It means that the language has high intelligibility and the music is well-defined.
Balance: It refers to the proportion coordination of the various parts of the music, and the consistency of the left and right channels is good.
Plump: It means that the middle of the sound is full, the treble is moderate, the loudness is appropriate, and the listening is warm, comfortable and flexible.
Strength: It means that the sound is solid and powerful, can have a sense of desire, and can reflect the dynamic range of the sound source.
Yuan Run: It means that the sound is beautiful, shiny and not noisy.
Soft: It means that the sound is not tight, the high sound is not harsh, and the listening is pleasant and comfortable.
Fusion: It means that the sound can be blended together, and the overall sense is good.
Realism: It means that the sound can maintain the original sound.
The sense of presence: replaying the sound makes people feel immersive.
Three-dimensional sense: refers to the sound has a sense of space, the sound image orientation is accurate, and has a sense of width and depth.
Total impression: refers to the overall feeling of the sound.
Test the speaker , divided into subjective test and objective test. Objective testing mainly refers to the analysis of the speaker design structure, circuit, and the use of special instruments to test the speaker signal-to-noise ratio, frequency response and other parameters. As an ordinary user, we certainly cannot have these high-end devices, so we mainly rely on various audio test software for playback and listening of a single audio signal. For example, special audio signal test CD, DavidsAudio Sweep Generator software and "short song audio tester" software. The main points of attention are:

1. The audio signal playback should be uniform and straight, and there must be no special highlighting or weakening;
2, in the theoretical minimum playback range or 20KHz, there should be no sound, otherwise it is likely to be the wrong noise;
3. The crime of adding bad signals is far greater than the crime of reducing signals;
4. Small changes in objective tests can have a big impact on actual use.
The subjective test problem is much more complicated, because each person's physiological characteristics are different and the aesthetics are different. So it is difficult to have a unified standard. This is why true HI-FI testing does not consider subjective testing as a decisive criterion. But despite this, some common standards are still there.

First, we must choose the appropriate frame of reference. In fact, for most people, the level of the auditory organs is almost the same, and there are very few people with real "golden ears". The reason why experts or enthusiasts feel the sound quality and judgment of the speaker is much higher than the average person, only because they often touch the high-end HI-FI audio equipment, and establish a correct listening concept and sound quality reference standard. Only.

Relatively speaking, ordinary multimedia speaker users lack such conditions, so they often establish wrong listening concepts and make wrong choices. For example, many people feel that they are listening to a good box in the computer market. It is often not a taste to take it home, but they don't understand what is going on. This is the result of not understanding the performance of the near-field system in different environments. What's more, many friends can use the speaker to listen to the human voice to hear the "tooth" as a good speaker standard, in fact, can hear the tooth sound, although the resolution of this speaker is good, but it often shows that this speaker is There is a problem with the crossover on a certain audio segment - the sound engineer and the mixer are not fools. They may want to listen to the singer's exhalation and mix it in the song while processing the recording.

This is the wrong choice caused by the wrong listening concept.
One way to solve this problem is to use headphones as a reference for the speakers . Because at a certain price, it is easier to make the sound quality better than the speaker at the same cost. In general, a Walkman earphone with a price of more than 200 yuan or a headset with a price of more than 400 yuan will have much better sound quality than most multimedia speakers , and the sound will be much more correct. Therefore, often listening to the sound of these high-end headphones, for most people, is a suitable alternative to the HI-FI reference system.

Second, we must choose the appropriate playback track Recently, in the test article of multimedia speakers , it seems to form a trend, as long as the test IF, take Tsai Chin's tracks out, and test the low frequency, then use the "A sister drum" Even "The Clouds and Wild Cranes". The author is extremely dissatisfied with this.

The reason is very simple. Tsai Chin's song is indeed the top grade in the vocals, but in general, the voice of Tsai Chin, as long as the medium frequency has a certain quality of the speaker will not be too difficult to listen, if it really sounds very bad, then this speaker The intermediate frequency is also bad. Although Tsai Chin's track has a lot of subtleties, it can really test the ability of the speaker , but these things are not just a lot of listening experience people can listen to it all at once. If you test a low-end device such as a multimedia speaker , some are more suitable singers and songs than Tsai Chin. In fact, because Cai Qin's voice is rarely flawed, it is not as good as some songs with poor sound quality. The songs of the singers are suitable for testing such low-end speakers . The reason is very simple. On a low-level speaker , Tsai Chin’s voice may still be Can barely accept, and the song of the singer whose sound condition is not good may be too bad to hear.

As for the "A Sister Drum" and "The Wild Cloud Crane", it is a bit of a joke. Even if the two songs use the real primary HI-FI speaker, they may not be able to perform well. What can you hear with the multimedia speakers ? Do you have to compare "the distortion of this speaker is a bit more, the noise of that speaker is a little more"? Some people have to add a snake to add a sentence, "Of course, for this multimedia speaker , don't expect it to play back this song well" - you don't expect that you have any use for this test? !

In fact, it is clear that the root cause of this phenomenon is that the authors of the article do not have any clear concept of test track selection. They only use some of these tracks in the authoritative test report, but they do not look at it. Look at people who are using these songs when testing what equipment - people's home "Free Cloud Wild Crane" is tested by the Rambler S5.1, Swans M-200 quasi-HI-FI level speakers , when have you seen people use it to test Cheap speakers of more than one hundred dollars? This is simply a typical painting tiger.
In fact, testing the low frequency of multimedia speakers , the famous TARLAC "big movie" album is more suitable, but it is not used.
Therefore, the test speaker must select the appropriate test track according to the characteristics of the speaker itself. In particular, you should try to choose the track you are familiar with, so that you can have a really good comparison. Although the track itself may be suitable for testing speakers , if you are not familiar with this track, how can you know what effect the speaker should show?

Third, even if you can't hear it, it's better than "listening much". As mentioned above, if you can't play well, you can't hear some sound signals, which is better than the wrong sound. Therefore, it is better to "cannot hear" and not to "listen much". This is an important criterion for judging. For example, if you hear your own subwoofer sound at 20Hz - don't be happy, it just means that your subwoofer is not good, there is resonance overtone at low frequencies and the designer has not taken any measures to correct it. Because the multimedia subwoofer should actually be at this frequency because the speaker output power is too low, the sound pressure is too weak, and the sound is lower than the indoor background noise. It is right that almost no sound can be heard. It is because of the existence of these low-frequency overtones that the sound quality of the subwoofer will deteriorate and become "boring". The appropriate comment on this subwoofer should be "poor control of the low frequency" rather than "the low frequency dive is unexpected" written in some articles - it is useless and the sound quality is the first. For multimedia subwoofers, there are few products that can control frequencies below the theoretical dive depth.

Fourth, the midrange is the most important midrange, this is the soul of music. Most of the expressiveness of music is in the midrange. Multimedia speakers used to have a period of popular highs, but now they are popular bass. But keep in mind that treble and bass can make a relatively deep impression, but poor midrange music is always hard to hear.

5. It is a good speaker that can be heard. The ideal multimedia speaker should have a good image and should have a clear positioning. Positioning a fuzzy speaker indicates that there is a problem with its signal processing.

Six, can hear the subtle sound of a good speaker speaker size to detail the extent of performance rather than its sound performance is good or bad. In the computer market, dealers often use their "hot" music to express their products, but remember that these pieces are easy to leave a deep impression, but they will also cover up the real weakness of the equipment.

Seven, can make people forget the speaker is a good speaker Good speaker , you should not feel the presence of the speaker when you close your eyes, but you can feel a complete sound field in front of you, if you can clearly Listening to the position of the speaker , that is not a good speaker anyway.

Eight, it sounds like a good speaker. A good speaker . A good speaker should be able to make people listen for a long time without bothering and not being noisy. Some speakers with high-pitched or low-pitched sounds may sound distinctive at first, but they are very impressive, but listening for a long time becomes uncomfortable. Remember, only after you can listen for a long time, there will still be no discomfort, and the subjective feelings are still pleasant, which is the real good speaker .
Use articles - use of multimedia speakers and tuning This chapter describes the placement, tone and other issues multimedia speakers in actual use to face, in particular, it noted that the multimedia speaker despite the use of simple, but requires careful use in order to have Good results.
Not having a good speaker , you can enjoy good music. If you don't pay attention to it, then a good speaker may only be half the battle.

First, the placement of the speaker , this is the common sense knowledge of HI-FI, but for the users of multimedia speakers , many people do not seem to be accustomed to pay attention to this problem, in fact, the impact of the placement on the sound quality of the speaker is still relatively obviously.
For bookshelf speakers , the situation is relatively simple, generally only on the front side of the Chen placed. If the place is small, consider tilting slightly to the inside to enhance the positioning effect. But there are two details to note:

1. The multimedia speaker is placed on the computer desk, there is a problem of resonance. For the HI-FI speaker , a special tripod will be used to solve this problem, but the multimedia speaker certainly does not have this condition. So the solution is to use the feet to reduce resonance. Although rubber feet have been installed on some high-end speakers , the results are not very satisfactory. Therefore, it is recommended to use a coin or a chess piece on the speaker's four-foot pad. At the same time, it is best to press a heavy object such as a book on the box.

2, for the rear phase box, the best inversion effect is required. It is best to keep the rear of the speaker at a distance of 1 to half a meter from the wall. If the size is too large or too small, the sound quality will deteriorate. . If you can't get away from the wall, you can put some sponge and other materials on the back wall to reduce the possibility of standing waves.

For X.1 speakers , it is much more troublesome.
First of all, it is important to understand that although many articles say that people are not sensitive to the orientation of the bass, the subwoofer can be placed anywhere in the room. But in fact only the real AV subwoofer is like this. Because the subwoofer of multimedia speakers generally has an upper limit of at least 300 Hz, the upper limit of some 2.1 speakers can reach 3000 Hz. This sound is impossible to hear.
Therefore, the correct placement of the subwoofer should be placed under the computer desk, directly below the display, with its front facing the user. If you have a lateral or backward phase-inverted hole, you should make it face the wall and keep a distance from the wall to enhance the bass.
The placement of the surround speakers of the X.1 speakers is also problematic. In general, the surround speakers of the X.1 speakers use the same method as the bookshelf directly on the table. The problem is that this makes the entire speaker position lower than the human ear. Usually, the position of the speaker is that the tweeter is at the same level as the human ear, so that a normal sound field can be established. It is not difficult for the bookshelf to meet this requirement, but on X.1 it will be felt that the sound is coming from below, which is obviously not right.
In order to solve this problem, many X.1 speakers adopt a design in which the front surface is tilted backward, but the actual improvement is very limited. Therefore, the correct positioning of the X.1 speaker main speaker should be based on other measures to support the main speaker in the same position as the human ear. After the X.1 speaker is placed, the sound field is placed in the original There is a change from the desktop.
4.1, 5.1, etc. For the speaker, followed by placement of the center speaker should be the best and the front speakers to the listener is symmetrical, but in practice since such a place is difficult, so many people commonly used is The rear speakers are placed on the same level as the listener. However, a big problem with such placement is that the sound of the rear left and right channels will be offset, and the actual sound intensity will drop a lot.
Second, the volume adjustment of the tuning speaker seems to be very simple, but it is not the case. Different adjustment methods have different effects.
Because both the speaker and the sound card have a volume adjustment function, how should I adjust it?
First of all, we should figure out who should be the main adjustment tool?
In fact, I also want to understand that even with the cable control or remote control, it is better to use the mouse to drag the adjustment lever than to adjust the potentiometer. And more importantly, the popular multimedia keyboard now comes with a volume adjustment button that can be quantified to make volume adjustments, and many audio software also supports hotkeys to adjust the volume. These are easier than using the potentiometer on the speaker , especially the bookshelf speakers behind the potentiometer.
Secondly, if the sound card is the main adjustment tool, then where should the speaker 's potentiometer be placed?
Some people may want to put it in the maximum position. Of course, this can get the maximum volume adjustment range, but the problem is that on many speakers , the maximum scale is already in the amplifier overload range. If the input is large, it is likely to Burn out the speaker. Moreover, the power amplifier circuit exhibits a good working state only in a range, and has been severely distorted at the maximum power.
Therefore, in combination with the above conditions, the most ideal way to adjust the volume should be to place the speaker 's volume potentiometer at 70%-80%, and adjust the volume of the sound card to adjust the volume of the system.

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