【 Weak current College 】 microphone introduction

The handset also known as the microphone, an electroacoustic equipment, microphone, sound power conversion transducers, through Sonic effect to produce electro-acoustic components, and then converted to power voltage. For a variety of sound amplifying equipment. Microphone, circuit is simple. Analysis of microphone circuit main master two points: (1) signal transmission circuit analysis, relatively simple, analysis of various microphone input jack on the circuit. (2) microphone signal amplifier, microphone amplifier is a small signal low-noise audio amplifier, analysis of the microphone level control circuit is not difficult.

Microphone classification

Microphones are usually the way it is converted to energy. Here we are at the Studio on the most general classification of the microphone, the microphone into dynamic microphone and capacitor microphone.

Dynamic microphone: the magnetic field generated by the conductor in the movement of the microphone signal. Is driven by the diaphragm vibration, so that the coil in a magnetic field coil induces voltage. Characteristics: strong structure, stable performance, durability, lower prices; frequency characteristics of sound, 50-15000Hz frequency range of amplitude-frequency characteristic curve flattened; links to good without DC operating voltage, low noise, easy to use.

Capacitor microphone: this type of microphone diaphragm is a capacitor electrode when the diaphragm vibration, diaphragm and a fixed distance between the plates after following the changes, creating a variable capacitance, the variable capacitance and microphone itself with preamplifier with produced signal voltage. Characteristics: good frequency characteristics in the audio range of amplitude-frequency characteristic curve is flat, this is better than dynamic microphone; non-directional, high sensitivity, low noise, timbre; output signal level is relatively large, low distortion, excellent transient response performance, this is a dynamic microphone are unattainable advantages; work characteristics not enough stability, low frequency sensitivity with the use of the increase of the time, life is short, the work requires the use of DC power supply lead.

Capacitor microphone in the preamplifier, and, of course, you have to have a power relationship, due to the volume, this power is usually placed in the microphone. In addition to the supply voltage capacitor membrane polarization, as preamplifier tube or supply the necessary voltage transistors. We call it the phantom power supply.

Thanks to this preamplifier, capacitor microphone is relatively sensitive to some, the use of some ancillary equipment: shockproof mechanism (usually with microphone gift), wind-proof cover, BOP cover, high-quality microphone stand. If you want to be super close-up recordings, a BoP cover is indispensable.

Microphone characteristics

Phone: generally consists of heart-shaped, hyper-cardioid, 8 glyphs, guns, omnidirectional point to. Please see Figure 02

As regards these point to what you can try to find a microphone. As shown in the direction of the arrow to the receiver within the meaning of the front, a dotted line to pickup the general scope, in this scope, the pickup will be insensitive. If you have suggestions or find conditions more than try to microphone, you can understand the meaning of point.

Microphone impedance: professional recording studios should use low impedance microphone, because it is possible to use very long cables to connect, so low impedance microphone can reduce the signal attenuation.

Balance line and non-equilibrium line: balance line consists of two conductors and a shield lines; non-equilibrium line only one wire shielded cable, replace the second wire.

The advantage of balanced line, the line of two wires to pick up unwanted noise signal strength are equal, so they can offset each other. And non-equilibrium line then the noise signal transmission to the next level of line.

If the audio signal is strong or very short non-equilibrium line, you may not hear noise. But the phone lines are long, think about it, we pulled from the Studio to make outgoing line, sound box over the wall and then entered the control room of tuning and sound recording system. Therefore, we want to use balanced lines, and the use of balanced XLR Plug:, commonly known as Canon head or boar's head; or the big three-core of TRS.