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The main technical characteristics of the microphone

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<p>I. Types of <a href="https://www.winwinindustry.com/product" rel="noopener noreferrer" target="_blank">microphones</a>: Microphones are generally divided into dynamic coil type, crystal type, carbon particle type, aluminum ribbon type, and condenser type according to their structure. The most commonly used are dynamic coil type and condenser type. The former is durable and cheap, while the latter is delicate and expensive, but has excellent characteristics.</p><p>The dynamic coil microphone uses the diaphragm to sense the change in air pressure caused by the sound waves, and drives the coil placed in the magnetic field to cut the magnetic lines of force to generate a weak current signal corresponding to the change in sound pressure intensity. Generally speaking, the dynamic microphone has low noise, does not need to feed power, is easy to use, and has stable and reliable performance.</p><p>The heart of a condenser microphone is a capacitive sensor. The two poles of the capacitor are separated by a narrow air gap, which forms the capacitor's dielectric. When a voltage is applied between the two poles of the capacitor, the sound vibration causes the capacitance to change, and the current in the circuit also changes. This signal is amplified and output to obtain a fairly good audio signal. In addition, there is a stationary condenser microphone. The diaphragm electrode is made of a stationary body material, which can work without the need of an external polarization voltage, which simplifies the structure. Therefore, this microphone is very compact and cheap, and also has the characteristics of a condenser microphone. , Is widely used in a variety of audio equipment and pickup environment. The condenser microphone has high sensitivity, good frequency response and good sound quality.</p><p>Second, the main technical characteristics of the microphone</p><p>1. Sensitivity: at a frequency of 1KHz, when the specified sound pressure of 0.1Pa is input from the 0 ° spindle on the front of the microphone, the output voltage of the microphone's output is open-circuited, the unit is 10mV / Pa. Sensitivity is related to output impedance. It is sometimes expressed in decibels, and 10V / Pa is specified as 0dB. Because the microphone output is generally in the millivolt level, the decibel value of its sensitivity is always negative.</p><p>2. Frequency response characteristics: The sensitivity of the microphone's 0 ° spindle changes with frequency. An appropriate frequency response range is required, and the characteristic curve within this range should be as smooth as possible to improve sound quality and suppress acoustic feedback. The same sound pressure, but the sensitivity of different frequencies when the sound is applied to the microphone is not the same, the frequency response characteristic is usually expressed by the decibel number of the sensitivity difference in the passband range. The wider the passband range, the fewer the decibels of the difference, indicating the better the frequency response characteristics of the microphone, that is, the less the frequency distortion of the microphone.</p><p>3. Directivity: The microphone's sensitivity to sound from different directions will be different, which is called the directivity of the microphone. Directivity is related to frequency. The higher the frequency, the stronger the directivity. In order to ensure the sound quality, the microphone should be relatively directional in the frequency response range. The directivity is expressed by the difference in sensitivity between the 0 ° direction of the front of the microphone and the 180 ° direction of the back. The difference greater than 15dB is called a strong directivity microphone. Product manuals often give directional polar coordinate response curve patterns for the main frequencies. The general types are: unidirectional "heart"; bidirectional "eight figure"; and nondirectional "circular"; and single Directional "Super Heart". The directivity of microphone sensitivity is an important factor in choosing a microphone. Some microphones are unidirectional, some are omnidirectional, and some are in between, and their directivity is heart-shaped. The omnidirectional microphone has the same ability to pick up sound from all directions. This type of microphone is more suitable when the <a href="https://www.winwinindustry.com/product" rel="noopener noreferrer" target="_blank">speaker</a> is going back and forth, but it should not be used under the condition of high ambient noise. The sensitivity of the cardioid pointing microphone is heart-shaped in the horizontal direction, the maximum sensitivity on the front is slightly smaller on the side, and the back is the smallest. This microphone has excellent performance in a variety of sound reinforcement systems. A unidirectional microphone is also called a supercardioid directional microphone. Its directivity is sharper than a cardioid microphone, its frontal sensitivity is extremely high, and its sensitivity in other directions is sharply attenuated.</p><p>4. Output impedance: The impedance of the microphone itself seen from the two ends of the lead of the microphone is called the output impedance. Commonly used microphones are divided into high impedance and low impedance. The value of high impedance is about 1000 ~ 20,000 ohms, which can be directly connected to the amplifier; the low impedance type is 50 ~ 1000 ohms, which can only be connected to the amplifier after matching the transformer. The output voltage of the high impedance is slightly higher, but the bypass capacitor plays a larger role in bypassing the high frequency, and it is also susceptible to external electromagnetic field interference. Therefore, the microphone lead should not be too long, generally 10 to 20 meters should. Low-impedance output does not have this defect, so the noise level is low. The microphone lead can be lengthened accordingly. Some low-impedance microphone leads that are provided with sound reinforcement equipment can reach 100 meters. If the distance is longer, a pre-amplifier should be added.</p>

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