Gain, PAD, EQ, PAN, PEL, AUX, etc., as a beginner, when we get an analog mixer (hereinafter referred to as the mixer), we often encounter these confusing words. In this article, we will explain these words in detail.
The main contents of this article include:
1. The role of the mixer in the sound system.
2. The main functions of the mixer.
3. Explanation of some function keys of the mixer
Part 1: The role of the mixer in the sound system
The simplest sound system, from the sound source to the audience, usually contains sound source (live sound/recorded sound)-mixer-amplifier-speaker, a total of 4 components. For different use occasions, such as churches, lectures, performances, training, conferences, etc., other professional audio processing equipment, such as equalizers, delayers, exciters, and timers, will be added as needed. Among them, the mixer plays a crucial role to link the entire sound system. Therefore, the flexible use of the mixer can take care of the hearing experience of most listeners as much as possible.
Part 2: The main functions of the mixer
1. Allocate audio signals. Audio signals can come from microphones, musical instruments, DVD boxes, etc. There are two kinds of interfaces for receiving audio signals on the mixer: XLR and Line interfaces. A wired microphone with an XLR interface (three-core) can be connected to the matching XLR interface on the mixer and requires a 48V phantom power supply. Other plug-in devices are connected to the mixer through the Line interface. When the tuner controls the mixer, he can distribute the audio signals of different lines to different speakers according to the needs of the scene. There are several different classification methods for speakers. According to the purpose of speakers, they generally include main amplifier speakers, return speakers, monitor speakers, etc.
2. Adjust the sound quality. Generally speaking, each input channel of the mixer has a three-band EQ (equalizer) adjustment knob: HF (High Frequency), MF (Medium Frequency), and LF (Low Frequency). By turning the knob, the audio signal can be compensated. “Defects” to improve the quality of audio signals to achieve the basic requirement of frequency balance. In modern audio equipment, a multi-band frequency equalizer is also specially equipped.
3. Adjust the volume. There are 3 places to adjust the volume on the mixer:
(1) Total volume fader
(2) Volume fader of each channel
(3) Gain knob (Gain: adjust the sensitivity of the input signal, the greater the adjustment, the higher the sensitivity, relatively speaking, the volume will also increase)
4. Auxiliary output. Generally, each channel of the mixer is designed with 2~6 auxiliary send buttons (AUX). These knobs can control the amount of signal sent by the channel to each auxiliary output (Aux SEND), and send the audio signal to the return speaker, subwoofer, effector, etc.
Part 3: Explanation of the function keys of the mixer
1. XLR (MIC)/Line audio signal access port: The XLR interface has three-core, four-core, five-core, and other different styles of connectors. The three-core connector is by far the most common style and is the industry standard for balanced audio signals. XLR receives low-level signals, with strong anti-interference and low noise. Most professional wired microphones use XLR three-core interfaces. The line is a “1/4” large three-pin socket, using a “1/4” large three-pin plug (TRS), tip (Tip), ring (Ring), sleeve (Sleeve), as the input of the balanced signal. Its input impedance is high, and it is generally used for input jacks of other sound sources except for microphones.
2. PAD (Passive Attenuation device): used to attenuate the MIC/Line signal. Generally, the signal of the Line is relatively large and needs to be attenuated. Press this key, the input audio signal will be attenuated by 20dB (that is, 10 times), and the attenuation value set by different mixers may be different.
3. Gain (gain adjustment): used to adjust the amplification of the input audio signal, which can amplify and attenuate the signal. It is equivalent to a small power amplifier.
4. Low cut: Low cut filter. Press this key to cut the frequency components of the input audio signal below 75Hz (the values set by different mixers are different). This button can be used when the sound reinforcement environment is poor.
5. EQ (equalizer): Mainly used for sound quality compensation. You can refer to the brief introduction in point 3 of the second part.
6. AUX (Auxiliary): Adjusting the auxiliary output knob is equal to adjusting the size of the channel sound sent to the corresponding auxiliary bus. You can refer to the brief introduction in point 4 of the second part.
7. PAN: Sound and image adjustment. Used to adjust the stereo position of the channel signal between the left and right speakers.
In addition to the function keys listed here, different mixers will also have some other keys. You can learn more detailed parameters and usage information according to the instructions provided by the manufacturer.
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