Abstract: Speakers are also known as "horns." It is a very common electroacoustic transducer that is currently found everywhere in our lives. This article only introduces the basic characteristics of the speaker, the main types of speakers, the principle of the speaker and the introduction of the top ten brands in the national speaker. (1) The speaker has two binding posts (two leads). When a single speaker is used, the two pins are not positive or negative. When multiple speakers are used at the same time, the two pins have polarity. (2) The speaker has a paper cone, which is usually black in color and white. (3) The shape of the speaker is round, square and elliptical. (4) The back of the speaker cone is a magnet. When the external magnetic speaker uses a metal screwdriver to touch the magnet, it will feel the presence of magnetism; the inner magnetic speaker does not have this feeling, but there is a magnet inside the casing. (5) The speaker is mounted on the machine panel or in the speaker. There are many types of speakers, which can be divided into electric type (ie moving coil type), electrostatic type (ie capacitive type), electromagnetic type (ie reed type), piezoelectric type (ie crystal type), etc. according to their transducing principles. The latter two are mostly used in rural cable broadcasting networks; they can be divided into low frequency speakers, intermediate frequency speakers, and high frequency speakers according to the frequency range, which are often used as combined speakers in the speakers. According to the conversion mechanism and structure, the split type (electric), capacitive (electrostatic), piezoelectric (crystal or ceramic), electromagnetic (pressure spring), ionized and pneumatic speakers, etc. The speaker has the advantages of good electroacoustic performance, firm structure and low cost, and is widely used; According to the sound radiation material, the paper basin type, the horn type and the diaphragm type; according to the shape of the paper cone, the circle, the oval shape, the double paper cone and the rubber folding ring; according to the working frequency, the bass, the middle sound, the high sound, and some are divided into Recorder-specific, TV-specific, normal and high-fidelity speakers; low-impedance and high-impedance by voice coil impedance; direct-spoke and ambient sound according to the effect. Speakers are divided into built-in speakers and external speakers, while external speakers are commonly referred to as speakers. The built-in speaker means that the MP4 player has a built-in speaker, so that the user can listen to the sound of the MP4 player through the headphone jack or through the built-in speaker. The MP4 player with built-in speaker eliminates the need for an external speaker and avoids the inconvenience of wearing a headset for a long time. The main performance indicators of the speaker are: sensitivity, frequency response, rated power, rated impedance, directivity and distortion. 1, rated power The power of the speaker is divided into nominal power and maximum power. The nominal power is called rated power and undistorted power. It refers to the maximum input power allowed by the speaker within the rated distortion range. The power indicated in the speaker's trademark and technical specification is the power value. The maximum power is the peak power that the speaker can withstand at a certain moment. In order to ensure the reliability of the speaker operation, the maximum power of the speaker is required to be 2~3 times of the nominal power. 2. The impedance of the rated impedance speaker is generally related to the frequency. The rated impedance is the impedance measured from the speaker input when the audio is 400 Hz. It is generally 1.2 to 1.5 times the voice coil DC resistance. The common impedance of general moving coil speakers is 4Ω, 8Ω, 16Ω, 32Ω, etc. 3, frequency response When an audio signal of the same voltage and different frequency is applied to one speaker, the sound pressure generated will change. Generally, the sound pressure generated in the middle audio is large, and the sound pressure generated in the low audio and high audio is small. The range of high and low frequency frequencies when the sound pressure drops to a certain value of the middle audio is called the frequency response characteristic of the speaker. The ideal speaker frequency characteristic should be 20~20KHz, so that all the audio can be played back evenly, but this is not possible. Each speaker can only reproduce a certain part of the audio better. 4, distortion The phenomenon that the speaker cannot reproduce the original sound realistically is called distortion. There are two types of distortion: frequency distortion and nonlinear distortion. The frequency distortion is caused by the fact that the signal of some frequencies is stronger, and the signal of other frequencies is weaker. The distortion destroys the proportion of the original high and low sound, and changes the original sound color. The nonlinear distortion is caused by the vibration of the speaker vibration system and the fluctuation of the signal are not completely consistent, and a new frequency component is added to the output sound wave. 5, pointing characteristics It is used to characterize the sound pressure distribution characteristics of the loudspeaker radiating in all directions of space. The higher the frequency, the narrower the directivity, and the greater the directivity of the paper cone. A speaker is a device that converts electrical energy (output from a loudspeaker) into sound (mechanical energy). Depending on the structure, the speakers can be divided into electric, electromagnetic, and piezoelectric. The most commonly used in the e-education work is the electric speaker. The electric horn type speaker is also called a tweeter, and its structure is shown in FIG. It is mainly composed of three parts: magnetic circuit system, vibration system and auxiliary microphone. The magnetic circuit system and the vibration system are assembled together and are called the pronunciation head. The pronunciation head and the assistant sound can be separated and integrated into each other. The magnetic circuit system consists of permanent magnets and soft iron, and the magnetic field is concentrated in the gap. The vibration system consists of a diaphragm with a voice coil, and the voice coil is centered in the magnetic gap. When the audio current passes through the voice coil, the voice coil drives the diaphragm to move back and forth, causing the air to vibrate. Since the front of the pronunciation head is equipped with a helper, the air can be resonated, and a loud sound is emitted. "? Xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /" The electric paper cone speaker is also called a woofer, and its structure is shown in Figure 2. It is mainly composed of two parts: a magnetic circuit system and a vibration system. The magnetic circuit system consists of a ring-shaped permanent magnet and soft iron, and the magnetic field is concentrated at the gap. The vibrating system consists of a paper cone with a voice coil that holds the voice coil in the center of the magnetic gap. When an audio current passes, the voice coil moves back and forth with the paper cone under the action of the magnetic field force, thereby making a sound. In order to improve the sound quality and expand the effective frequency range, several speakers with different frequency response ranges are usually combined and incorporated into the same speaker to form a combined speaker. It allows for a significant improvement in the frequency response curve over the entire audio range.
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