When you are enjoying wonderful high-quality music, have you noticed that the two major components of high-quality music restoration are: high-quality source (software) and high-fidelity equipment (hardware)? The role of the film source and equipment in the restoration of music is the same as the relationship between the software and hardware of the computer, and no one can leave anyone.
In ancient times, people heard good music performance. Once the performance was over, the sound disappeared forever, and only the exclamation of "This song should only exist in the sky, and there are a few recollections in the world". But since Edison invented the phonograph in 1877, the development of electroacoustic technology has been rapid in the past 100 years. From coarse-grained records to dense-grained LP records and then to digital laser record CDs, laser video discs LD, and today's VCDs and DVDs, there are also magnetic recording equipment such as recorders, video recorders and digital magnetic recording equipment, etc .; others such as amplifiers, The principle and production of speaker production are changing with each passing day.
Due to the advancement of electronic and electro-acoustic technology, people can not only record beautiful and beautiful sounds, but also record them as realistically as possible and reproduce them as realistically as possible. This kind of audio equipment is generally called high-fidelity audio (English Hi-Fi, High fidelity.). Fever audio equipment is generally consistent with high-fidelity audio equipment.
Compared with predecessors, the current music hobby is lucky, as long as you have a set of high-fidelity audio equipment, you can enjoy all kinds of music you like at any time without leaving home, or you can enjoy the conductor conductor The wonderful performances of the world-class orchestra, enjoy the excellent performances of famous performers, and you can listen to them repeatedly at any time.
In Beijing, Shanghai, Guangzhou, Hong Kong, and Taiwan, almost all economically developed countries and regions have a large number of audio enthusiasts. Now a popular term, audio enthusiasts, referred to as audiophiles. The corresponding high-fidelity audio (Hi-Fi) also has an enduring market, becoming an important part of the consumer electronics market.
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 enthusiasts who have too much preference for music and audio equipment, the public also adopts a tolerant attitude. As for the very few people, the audio fever is so good that it can only be properly guided. There are also people who buy audio equipment and use expensive imports to win wealth to satisfy their own vanity, that is, two things that have nothing to do with music and audiophiles.
In the future, I will introduce some basic knowledge about audio equipment, selection and matching of equipment, DIY knowledge and other related issues. Due to limited personal level, most things are reprinted from the Internet or based on the original text. The above revision involves some specific problems or understanding of specific products. It is inevitable that there will be some bias. I hope everyone understands and welcomes your discussion.
1. Explanation of terms and terms of audio knowledge.
1. The development history of audio technology.
The development history of audio technology can be divided into four stages: electron tube, transistor, integrated circuit, and field effect tube. In 1906, American De Forrest invented the vacuum triode, setting a precedent for human electroacoustic technology. After Bell Labs invented negative feedback technology in 1927, the development of audio technology entered a new era. The more representative amplifiers such as "Williamson" used the negative feedback technology more successfully, which caused the distortion of the amplifier. Greatly reduced, the development of tube amplifiers reached a climax in the 1950s, and various tube amplifiers emerged endlessly. Due to the sweet and round sound of the tube amplifier, it is still preferred by audiophiles. The emergence of transistors in the 1960s has brought the vast number of audio enthusiasts into a broader world of audio. The transistor amplifier has the characteristics of delicate and beautiful sound, lower distortion, wider frequency response and dynamic range. In the early 1960s, the United States first introduced a new member of the audio technology-integrated circuits. By the early 1970s, integrated circuits were gradually recognized by the audio industry for their high quality, low price, small size, and multiple functions. Since its development, thick film sound integrated circuits and operational amplifier integrated circuits have been widely used in sound circuits. In the mid-1970s, Japan produced the first field effect power tube. The field effect power tube has the characteristics of pure tube, sweet sound, and dynamic range of 90dB, total harmonic distortion THD "0.01% (at 100kHz), which soon became popular in the audio industry. Many current amplifiers use field effect transistors as the final output. The development of audio technology has experienced the historical period of electron tubes, transistors, and field effect tubes, and each has its own characteristics in different historical periods. It is expected that the mainstream of audio technology in the future will be digital audio technology.
Introduce the specific meaning of dB. The unit dB is a very widely used in electronics. It is a relative unit for measuring and comparing the power, voltage and current of a system. Later, due to the advancement of technology, it was recognized that the human response to sound changes according to the law of logarithm, so there was a unit called Bel, who was the inventor of the telephone. The expression is: Bel = lg (P / Po) P is the measured power Po is the reference power: Bel represents the logarithm to base 10. In fact, it was found that Bel was too large, so tenths of it was taken as a new unit, that is, the decibel (dB) divided by Bel is 10 is the dB expression is: dB = 10lg (P / Po), dB = 20lg (E / Eo ), DB = 20lg (I / Io).
2. What is Hi-Fi?
What kind of audio equipment is Hi-Fi? Hi-Fi is the abbreviation of English High-Fidelity, literally translated as "high fidelity", its definition is: replay sound highly similar to the original sound. So what kind of audio equipment's playback sound is Hi-Fi? So far it is still difficult to draw definitive conclusions. Professionals in the audio industry use various instruments and various means to detect various indicators to determine the level of Hi-Fi equipment, and audiophiles often use their ears to judge whether the equipment reaches the Hi-Fi in mind. . To determine the level of high fidelity of the playback sound, not only the equipment and software with excellent performance are required, but also a good listening environment. Therefore, there is a difference between objective testing and subjective evaluation on how to correctly measure the Hi-Fi degree of audio equipment.
3. The main technical indicators of the sound system.
The performance of the overall technical indicators of the audio system depends on the performance of each unit. If the technical indicators of each unit in the system are high, the overall technical indicators of the system are very good. There are six main technical indicators: frequency response, signal-to-noise ratio, dynamic range, distortion, transient response, stereo separation, and stereo balance.
1. Frequency response: The so-called frequency response refers to the relationship between the frequency range of sound equipment and the amplitude of sound waves with frequency. Generally, this index is measured with the frequency amplitude of 1000 Hz as the reference, and the amplitude of the frequency is expressed in decibels (dB) in logarithm. The overall frequency response of the sound system is theoretically required to be 20 ~ 20000Hz. In actual use, due to circuit structure, component quality, etc., this requirement is often not met, but generally at least 32 ~ 18000Hz.
2. Signal to noise ratio:
The so-called signal-to-noise ratio refers to the ratio of the sound system's replay sound of the sound source software to the new noise generated by the entire system. Its noise mainly includes thermal noise, AC noise, mechanical noise and so on. Generally, this index is expressed in decibels (dB) of the logarithmic ratio of the rated output power of the playback signal and the system noise output power when there is no signal input. The signal-to-noise ratio of a general audio system needs to be above 85dB.
3. Dynamic range:
The dynamic range refers to the logarithmic value of the ratio of the maximum undistorted output power of the audio system during playback to the system noise output power at static, in decibels (dB). The dynamic range of a sound system with good general performance is above 100 (dB).
4. Distortion: Distortion means that after the sound system reproduces the sound source signal, some parts (waveform, frequency, etc.) of the original sound source signal have changed. The distortion of the sound system mainly includes the following: 1． Harmonic distortion: The so-called harmonic distortion refers to the sound system reproduced sound has many additional harmonic components than the original signal source. This additional harmonic component signal is a multiple or division of the signal source frequency, which is caused by the non-linear characteristics of the negative feedback network or amplifier. The harmonic distortion of the high-fidelity audio system should be less than 1%. 2. Intermodulation distortion: Intermodulation distortion is also a kind of nonlinear distortion. It is a mixture of more than two frequency components in a certain proportion. Each frequency signal is modulated with each other. After passing through the playback equipment, a newly added nonlinear signal is generated. This signal Including the sum and difference between the various signals. 3. Transient distortion: Transient distortion is also called transient response. Its generation is mainly due to the slower response of the amplifier when a large transient signal is suddenly added to the amplifier, thereby distorting the signal. Generally, after the input square wave signal passes through the playback device, observe whether the envelope waveform of the output signal of the amplifier is similar to the input square wave waveform to express the ability of the amplifier to follow the transient signal.
V. Stereo separation: Stereo separation indicates the isolation between the left and right channels in a stereo sound system. It actually reflects the degree of crosstalk between the left and right channels. If the crosstalk between the two channels is large, the stereo sound of the reproduced sound will be weakened.
6. Stereo balance:
The stereo balance indicates the difference between the gains of the left and right channels in the stereo playback system. If the unbalance is too large, the sound image localization of the reproduced stereo will be shifted. The stereo balance of a general high-quality sound system should be less than 1dB.
4. How is the sound range and audio range of the sound reproduced by the sound system divided? How does each band perform on music?
The range of the sound system's playback sound can generally be divided into eight ranges: subwoofer, bass, mid-bass, mid-range, mid-treble, sub-treble, treble, and ultra-high. The audio frequency range can generally be divided into four frequency bands, namely low frequency band (30 ~ 150Hz); middle frequency band (150 ~ 500Hz); middle high frequency band (500 ~ 5000Hz); high frequency band (5000 ~ 20000Hz). Among them, the 30 ~ 150Hz frequency band: can express the low-frequency components of music, so that the audience feels a strong and dynamic feeling. 150 ~ 500Hz frequency band: It can express the performance of a single percussion instrument in music, which is the part of expressing the strength in low frequency. 500 ~ 5000Hz frequency band: mainly expresses the clarity of the singer's language and the expressiveness of the string. 5000 ~ 20000Hz frequency band: mainly express the brightness of music, but too much will make the sound break.
5. What are the common terms for audiophiles.
The commonly used terms for audiophiles are more abstract. The commonly used terms are as follows: 1. Nerve line: mainly refers to the signal line that transmits low level (millivolt, microvolt level) and small current. Generally, the nerve cable is used for both audio and video. The plugs at both ends of the higher-level nerve cable are gold-plated RCA plugs, and an anti-static protective layer is coated on the surface of the wire. 2. Fever line: mainly refers to the speaker signal transmission line with a larger cross-section and more shares. The high-quality fever wire is made of oxygen-free copper and other materials. 3. Burning machine: The so-called burning machine is similar to the friction period of mechanical machines, that is, after the audio equipment works for a certain period of time, the temperature inside the machine is the same as the ambient temperature, so that the working state of the amplifiers at all levels reaches the best point, and playback The sound is best. 4. Motorbike: The so-called motorbike originates from the English Modify, which means modification and modification. Enthusiasts replace and modify the components or circuits in the audio system to upgrade it, which is called a motorcycle. 5. Bursting: The so-called bursting refers to the deafening atmosphere that occurs when the music enters the climax during the playback of audio equipment. 6. Amplifier: Amplifier refers to an amplifier made with a tube. The warm and transparent sound quality of the tube amplifier has made the older generation of enthusiasts still unforgettable. 7. Stone machine: The so-called stone machine refers to an amplifier made of transistors. 8. Gallstone machine: it is an audio equipment made by mixing electron tubes and transistors. Generally, the electron tube is used as the pre-amplifier, and the transistor is used as the post-amplifier. 9. Huanniu: The so-called Huanniu refers to a toroidal transformer, which has a smaller magnetic leakage compared to ordinary transformers. 10. Large pond: The large pond refers to the power filter capacitor, generally a large-capacity capacitor of more than 10000μF. 11. Beautiful sound: refers to the sound quality of the audio equipment's replay, which meets the requirements of high fidelity. 12. Resolution: It means that the replay of audio equipment has a certain degree of transparency, giving people the feeling of "clear bottom". 13. Dyeing: The so-called dyeing refers to the sound that is not in the reproduced sound produced by the resonance of other objects or materials due to the vibration of the sound wave during the reproduction. It is harmful to the effect of replay. 14. Microphone: Refers to various microphones. 15. Supplements: Refers to the higher quality components used in the transformation of the sound system.
6. How should the speakers be placed?
The correct placement of the speaker is one of the factors to obtain a good sound effect. When placing it, you must pay attention to the following issues: 1. The distance between the two speakers is not less than 1.5 ~ 2 meters, and keep the same level. The distance between the left and right sides of the speaker and the wall should be the same. There should be no debris in front of the speaker. . 2. The tweeter of the speaker and the ear of the listener should maintain the same horizontal line, and the angle between the listener and the two speakers should be 60 degrees, and a certain space should be left behind the listener. 3. The walls on both sides of the two speakers should be acoustically consistent, that is, the reflection of sound waves by the walls on both sides should be the same. 4. If the directionality of the sound waves of the speakers is not wide, you can place the two speakers slightly inward. 5. For small speakers, if the low frequency is not enough, you can place the speaker close to the corner.
7. What problems should be paid attention to when connecting audio equipment?
The matching between audio equipment at all levels is more important. Improper connection will not only affect the playback effect of the equipment, but also damage the equipment.
A. Basic requirements for equipment connection:
(1) Signal level matching: When connecting audio equipment, be sure to pay attention to the difference between the input and output signal levels of each equipment. If the level of the input signal of the pre-stage equipment is too large, nonlinear distortion will occur, otherwise the signal-to-noise ratio of the playback system will be reduced, and even the amplifier of the next-stage equipment will not be promoted. The levels should not differ too much. If the signal level does not match in actual use, the input signal level must be reduced by the attenuation circuit, or the input signal level should be increased by the amplification circuit. For a general dynamic microphone output voltage of a few millivolts, it is necessary to provide a first-stage amplifier circuit to amplify the signal and send it to the pre-amplifier circuit. For the recording base, CD player and LD player, because the output signal level reaches 0.755 ~ 1V or more, it can be directly sent to the preamplifier.
(2) Impedance matching: In Hi-Fi audio equipment, for example, the output impedance of the transistor power amplifier is low impedance, and the output impedance of the tube power amplifier and other equipment is high impedance. If they do not match the impedance when they are connected to the speaker, the output power of the amplifier will be unevenly distributed, or the transient characteristics of the speaker will deteriorate due to excessive damping. There are two types of impedance matching connections: balanced and unbalanced. The so-called balanced type means that the impedance of the two-core shielded wire transmitting the signal to the ground is equal. The so-called unbalanced type refers to one of the two core shielded wires, one of which is grounded. When the balanced output is connected with the unbalanced input, it must be matched by adding a matching transformer.
B. Connector connection method: In Hi-Fi audio equipment, the connection of equipment is completed by various connectors. Commonly used connectors are as follows.
(1) Two-pin plug: mainly used to transmit signals between various equipment and as an input plug for microphone input signals. According to its diameter, it can be divided into three types: 2.5mm, 3.5mm and 6.5mm.
(2) Lotus plug: It is mainly used for input and output plugs between audio equipment and video equipment.
(3) XLR plug (XLR): mainly used for the connection between the microphone and the amplifier.
(4) Five-core socket (DIN): It is mainly used for the connection between the cassette recorder and the amplifier. It can concentrate the stereo input and output signals on one socket.
(5) RCA plug: RCA plug is mainly used for the transmission of video signals in equipment.
(6) F, M plug: It is mainly used for the input and output of radio frequency signals in audio-visual equipment.
8. What is the "OFC" fever line? What are the "6N" and "7N" fever wires?
"OFC" is the abbreviation of "Oxygen Free Copper" in English, meaning "oxygen-free copper". As we all know, the resistivity of gold and silver in metal is the smallest, and the conductivity is the best. However, if gold and silver are used as the material for making the fever wire, the price is very expensive, which is not acceptable to most audiophiles. As a commonly used metal material, copper has better conductivity and is more commonly used, but because copper contains more impurities, most of which are oxides, which affects the conductivity of copper. Is it currently used that is called more? quot; "OFC" line of intelligent fever wire, which uses high-tech methods such as electrochemical method, PN junction implantation method, isotope irradiation modification method, etc. to change the metal structure of copper to produce copper wire surface The unique metal structure makes the surface of the same copper wire suitable for transmitting frequency signals above 5000Hz, while the center is only suitable for transmitting frequency signals below 5000Hz, so that high and low frequencies do not interfere with each other, which is beneficial when transmitting large signals , Improve the clarity of the playback sound, improve the sound quality of the playback sound.
"6N" and "7N" are used by enthusiasts to indicate the purity of the fever wire made of oxygen-free copper materials. Because the English "9" begins with the letter "N", for the convenience of expression, audiophiles use "N" for "9", and the number before "N" indicates how many "9". For example, "99.9999%", you can have "6N", which means that the purity is 6 9s, the larger the number in front of N, the higher the purity of the fever line.
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