Audio Common Sense: Some Things You Should Know About Audio

- Jul 06, 2020-

1. Impedance (want to know what this specific logistics unit means, Baidu know about it, the same below)

Impedance is not resistance. Everyone makes mistakes here. In fact, impedance is the sum of resistance and reactance. Resistance refers to the blocking effect of an object on current in direct current. At the AC point, in addition to resistance blocking current, capacitance and inductance also blocking current. This is reactance. According to the information I found, the impedance value has no critical effect on the sound quality. However, if the impedance is too low, resulting in excessive current, it is also easy to distort the sound. For players who like to listen to music, the impedance is relatively sensitive. Common values of speakers are, 4, 6, 8, 16 international recommended value is 8 ○ (this is the symbol of logistics ohm, can not be found... use circle instead) 2. Sensitivity

2 Sensitivity

It refers to the sound pressure level obtained by testing the sound pressure level in the front of the speaker at a distance of 1M from the center of each collection when the speaker inputs 1W of electrical power. The unit is DB. Put another way, the sensitivity is related to the volume of the speaker. Under the same volume conditions, speakers with higher sensitivity have much less possibility of sound distortion. The sensitivity of the speaker high-fidelity speaker is 86db, and the professional-grade speaker is more than 96db. You can refer to it when purchasing the speaker.

3. Power

Rated power: (RMS) In short, it is called effective power, that is, the maximum power value that the speaker can safely use for a long time without distortion. Under normal circumstances, only some manufacturers of large multimedia speakers have marked this value, most manufacturers mark the peak music output power.

Peak music output power (PMPO): This parameter is the trademark of most manufacturers, that is, the maximum output power of the power amplifier in the moment without distortion. This value does not consider distortion, but exceeds a certain range, does it make sense? In fact, we can get the ratio we need to the rated power through conversion. I don’t know the specifics. The data shows that the conversion ratio is 1 to 8.

4. Signal to noise ratio

Refers to the ratio of the normal sound signal played back by the speaker to the noise signal when there is no signal, also expressed in DB. The higher the value, the better the sound quality, but the higher the price... Generally, the signal-to-noise ratio of 2.0 speakers can reach 80db, and it can be larger. As for the X.1 speaker, as long as it is greater than 75db, it will be ok!

5. Speaker caliber

Some people think that the bigger the speaker caliber is, the better? of course not. Because the diameter of the speaker increases, the paper cone is easily deformed and damaged when it vibrates, which will also affect the sound quality. Therefore, the caliber of the low-frequency loudspeaker is generally 20-38cm, of course, there are also large-caliber cannons of 60 or 72cm. The caliber of the middle and high tweeter is usually between 2-6cm, and occasionally there are guys larger than 9cm

6. Distortion

Refers to the signal before being amplified by the amplifier, compared with the amplified signal, the difference between the amplified signal and the unamplified signal. The unit is a percentage. For multimedia speakers, distortion cannot be avoided, as long as it is controlled within a reasonable range. For example, 2.0 speakers must be below 1%, X.1 must be below 5%, 2.0 speakers must be below 1%, X.1 must be below 5%.

7. Weight

The heavier the speaker, the better the wood used, and the larger magnet inside, which can effectively improve the sound quality. So in short, it's better, because you are willing to use materials. (Do not rule out things like unscrupulous merchants stuffing bricks, it seems to have happened...)

1. As many channels as possible

This is the most obvious misunderstanding. In terms of distortion, the best speaker should be the 2.0 speaker. The X.1 speaker only provides stronger bass and surround effects. The sound quality has not been improved. Instead, it has compromised for the surround effect. .

2. Just a wooden speaker

In fact, the wood used for the speaker is divided into high-density board, medium-density board and low-density board. Some manufacturers promote it as a wooden speaker, and if a low-density board speaker is used, it is not as good as a well-designed plastic speaker. Similarly, there are aluminum speakers. The biggest advantage of aluminum speakers is that they can further eliminate resonance and improve sound quality. It should be better than wooden speakers, but their cost ratio is better. Frequency Range

The full name of the frequency response range is called frequency range and frequency response. The former refers to the range between the lowest effective playback frequency and the highest effective playback frequency of the speaker system; the latter refers to the connection of an audio signal output with a constant voltage to the system, the sound pressure generated by the speaker occurs with the change of frequency Increasing or attenuation, the phase changes with frequency, this kind of sound pressure and phase and frequency correlation change relationship is called frequency response, unit decibel (dB). The curves of sound pressure and phase lag with frequency change are called "amplitude frequency characteristic" and "phase frequency characteristic", collectively called "frequency characteristic". This is an important indicator to check the performance of the speaker. It has a direct relationship with the performance and price of the speaker. The smaller the decibel value, the flatter the frequency response curve of the speaker, the smaller the distortion, and the higher the performance. For example, the frequency response of a speaker is 60Hz~18kHz+/-3dB. Sometimes these two concepts are not distinguished, they are called frequency response. In theory, the harmonic components that make up sound are very complicated. It is not that the sound is more pleasant when the frequency range is wider, but this is basically correct for low-end and medium-end multimedia speakers. The current speaker manufacturers generally mark the frequency response range of the system too large, and the high frequency part is not very poor, but it is extremely unrealistic at the low end, so I would like to tell everyone that the low frequency sound must be heard and do not believe it. The value on the leaflet.

2. Sensitivity

This indicator refers to the sound pressure level measured when a 1W/1kHz signal is input to the speaker input terminal one meter in front of the vertical center axis of the speaker horn plane. The unit of sensitivity is decibel (dB). For every 3dB difference in the sensitivity of the speaker, the output sound pressure will be doubled. The sensitivity of the ordinary speaker is in the range of 85 to 90dB, and the sensitivity below 85dB is low, and the sensitivity above 90dB is high. Generally, the sensitivity of multimedia speakers is slightly lower.

3. power

The indicator is simpler, it feels how powerful the sound from the speaker can be. According to international standards, there are two methods for marking power: rated power and maximum withstand power (instantaneous power or peak power PMPO). The rated power refers to a continuous analog signal with a prescribed waveform for the speaker within the rated frequency range, the maximum undistorted power that the speaker can emit, and the maximum withstand power is the maximum electrical power without any damage to the speaker. Generally, in order to cater to consumer psychology, merchants usually mark the music power as very large, so when purchasing multimedia speakers, the rated power shall prevail. The maximum withstand power of the speaker is mainly determined by the chip power of the power amplifier, and also has a great relationship with the power transformer. You can roughly know the weight of the transformer by weighing the weight difference between the main and auxiliary speakers. Generally, the heavier the power, the greater the power. But the power of the speaker is not the greater the better, the application is the best. For the room of about 20 square meters for ordinary home users, the real 50W power is enough, there is no need to go too far to pursue high power.

4. Distortion

The definition of the distortion of the speaker is basically the same as the distortion of the amplifier. The difference is that the amplifier inputs an electrical signal, and the output is an electrical signal. The speaker inputs an electrical signal, and the output is an acoustic signal. Therefore, the distortion of the speaker refers to the distortion of the conversion of the electroacoustic signal. The allowable range of sound wave distortion is within 10%, and the general human ear is not sensitive to distortion within 5%. It is best not to buy speakers with a distortion greater than 5%.

5. Signal to noise ratio

This indicator refers to the ratio of the normal sound signal played back by the speaker to the noise signal. The signal-to-noise ratio is low, and the noise is serious when a small signal is input. The sound in the entire sound range obviously becomes muddy and unclear. I don’t know what sound is emitted, which seriously affects the sound quality. Speakers with a signal-to-noise ratio lower than 80dB (including subwoofers lower than 60dB) are not recommended for purchase. 6. impedance

The index refers to the ratio of the voltage and current of the input signal. The input impedance of the speaker is generally divided into two types: high impedance and low impedance. Generally, the impedance above 16 ohms is high impedance, and the impedance below 8 ohms is low impedance. The standard impedance of the speaker is 8 ohms. The nominal impedance of speakers on the market is 4 ohms, 5 ohms, 6 ohms, 8 ohms, 16 ohms, etc. Although this indicator has nothing to do with the performance of the speakers, it is best not to buy low-impedance speakers, the recommended value is the standard 8 ohms, this is because in the case of the same power amplifier and output power, low-impedance speakers can get a larger output power, but the impedance is too low will cause underdamping and bass degradation and other phenomena.

7. Sound technology

Hardware 3D audio technology is more common nowadays, such as SRS, APX, Q-SOUND, and Virtaul Dolby. Although they have different implementation methods, they can make people feel obvious three-dimensional effects. Among them, the first is the most common. They apply the extended stereo (Extended Stereo) theory, which is the additional processing of the sound signal through the circuit, so that the listener feels that the sound direction extends to the outside of the two speakers, so as to expand the sound, giving people a sense of space and The three-dimensional sense produces a wider stereo effect. In addition, there are two kinds of sound enhancement technologies: active electromechanical servo technology and BBE high-definition plateau sound playback system technology, which also has certain improvement in sound quality.

20 sound effects

One, sound quality:

Refers to the quality of the sound. Also known as timbre/tone, it not only refers to the quality of the timbre, but also refers to the clarity or fidelity of the sound. Example: When we evaluate the sound quality of a piece of audio equipment,

It's not about its sense of layering and positioning, but that it gives people a pleasant and comfortable listening experience. A sound device with good sound quality is like a good voice, which makes people hard to hear.

Second, the tone:

Refers to the color of the sound. (Pitch + overtone = timbre) Of course, we cannot see the color of the sound, but hear it. Example: The saying that the violin is really warm and cold is that the warmer the softer, the colder the harder. The shape, material, and overtones determine the timbre.

Third, the amount and control of high, medium, low and sense of quantity:

Sense of quantity means that there are more trebles and less bass. The control refers to the control of equipment, which can reflect the advantages and disadvantages of audio equipment.

Fourth, the sound field performance:

A good sound field shows its feelings as follows: 1. Intimacy (eg, the actor communicates with the audience, expressive) 2. Surrounding the scene.

The performance of the sound field can be divided into three parts to understand: 1, the position of the sound field 2, the depth of the sound field (for example: grasp the distance between the violin and the timpani and bass drum) 3, the width of the sound field (that is, where we are located In space only)

Fifth, the density and weight of sound:

Good sound density and weight, sound and instruments make people feel more stable, solid and more authentic. The high density and heavy weight give people a sense of hearing: string music is sticky, and the wind is thick and full. The percussion sounds vibrating when it is knocked on the air.

Sixth, transparency:

A good sense of transparency: soft, very clarified, so that the ears will not be tired. Bad transparency: It feels like a thin layer of mist. Although it is clear to see, it is very sad. Like a sun that hurts the eyes.

Seventh, sense of hierarchy:

Refers to whether the musical instruments can be clearly reproduced from the row after the row, that is to say, we want to hear the space between the instruments.

Eighth, sense of positioning:

It means to "fix" the location there. What we are asking for is to emboss and clearly shape the musical instruments and vocals.

Ninth, a sense of life:

It is the other side of instant reaction, sense of speed and contrast of strength and weakness. It allows us to listen to music very lively, not lifeless. This has a lot to do with whether the music is good or not.

Tenth, image power and physical sense:

It is the ability to condense the ethereal audio and video into a solid, that is, the ability to show the three-dimensional sense of the shape of human voices and musical instruments.

Eleventh. Resolution:

Even small and complex things can be clearly expressed. The analytical power can be divided into high-level analysis and low-level analysis: 1. High-level analysis and extremely high-level analysis are capable of analyzing all things clearly. 2. When the level is low, the subtle changes can be clearly expressed.

Twelfth. Instantaneous response and sense of speed:

The sense of speed is the result of an instant reaction. We are referring to the speed of the response of audio equipment. Thirteen, strong and weak contrast and dynamic contrast:

The strength contrast is dynamic contrast. We are referring to the contrast between loud and soft musical instruments. Example: (1, the contrast between the maximum and minimum sounds of classical music is very large, and the fluctuations are very large, so we say that its dynamic contrast is large. 2. Although the rock and roll music is very loud, the contrast between its loud and low sounds is not large, So we say that its dynamic ratio is not great.

Fourteenth. The size ratio of vocals to musical instruments:

The correct size ratio of vocals and musical instruments is not just a reduction in size, but the size ratio according to reasonable music.

Fifteenth. The texture and air of vocals and musical instruments:

Texture refers to the degree of facsimile, the feeling of being touched immediately after contact. The sense of air refers to the feeling of sound wave vibration. Example: (Texture of vocals, air sense of wind music)

Sixteenth, details regeneration:

Refers to the details of the instrument, the reproduction of the hall sound and all the noise in the recording space. Equipment with less details sounds dull, and equipment with more details sounds interesting.

Seventeenth, sense of space:

It means that the three-dimensional space of the recording place is large.

Eighteenth, overall balance:

Refers to the high, medium, low, moderate sense of quantity distribution.

Nineteenth: the personality of the equipment.

Twentieth: Recommendations for equipment matching

The above twenty are related to each other. After everyone deeply understands it, it is convenient to comment on the quality of the sound system equipment and the quality of its sound quality