Hello, I would like to ask how to distinguish the peripheral devices of analog mixer in your AV equipment, and what are their functions?

I haven't heard from you for several days, and I'm sorry I couldn't answer your question in time.

Analog mixer belongs to the category of audio equipment. A complete sound system is mainly composed of audio signal source, control and processing equipment, power amplification equipment and electroacoustic conversion equipment. In the control processing equipment, it includes: mixer and peripheral equipment. The so-called peripheral equipment refers to the equipment used around the mixer to complete the functions that the mixer itself cannot meet. For example: effect processor, equalizer, exciter, compressor, limiter, feedback suppressor, frequency divider, etc.

Equalizer: Equalizer (equalizer)

It is an electronic device that can adjust the amplification of electrical signals of various frequency components respectively. By adjusting the audio signals of different frequencies, we can compensate the defects of speakers and sound fields, and compensate and decorate various sound sources and other special functions. The equalizer on the general mixer can only adjust the high-frequency, medium-frequency and low-frequency electrical signals respectively, and can only make rough adjustment, which can not meet the requirements when it is used as room equalization processing or balancing system curves. Independent professional equalizer divides the audio signal from 20 Hz to 20 Hz into 15 segment or 3 1 segment, which will make the adjustment more accurate and make the frequency response curve of the system tend to be straight. But also can freely attenuate unnecessary frequencies; On the basis of speech enhancement, properly attenuating the howling frequency points in the system can also suppress howling to a certain extent.

In addition, the equalizer is divided into graphic equalizer and parameter equalizer, and the graphic equalizer is generally used in the peripheral system of the mixer.

Effector effect

Untreated music gives people a feeling of fly in the ointment. The effector is an electronic instrument dedicated to producing various effects. Its function is to change the waveform of the original sound, modulate or delay the phase of the sound wave, enhance the wave component of the sound wave and so on, and produce various special acoustic effects. In addition to conference speech enhancement, many voices and musical instruments will use effectors. When a singer sings, adding some reverberation can make the sound full, broad and lasting, but it sounds monotonous and straightforward without reverberation. Many musical instruments, such as electric guitar, bass and electronic drum, can also produce different styles of sound effects through effectors. These types of effects include: distortion, compressor, phase shifter movement, chorus, overspeed, edging, wow, delay and so on.

Stimulator

A harmonic generator uses the psychoacoustic characteristics of human beings to decorate and beautify sound signals. By adding high-frequency harmonic components to the sound, the sound quality and timbre can be improved, the penetration of the sound can be improved, and the sense of space of the sound can be increased. Most exciters can not only produce high-frequency harmonics, but also have the functions of low-frequency expansion and musical style, which makes the bass effect deeper, more shocking, fuller and more trustworthy. High-frequency excitation can improve the clarity, intelligibility and expressiveness of sound. Make the sound better, reduce hearing fatigue and increase loudness. Although the exciter only adds harmonic components of about 0.5dB to the sound, it actually sounds as if the volume has increased by about 10dB. The auditory loudness of the sound is obviously increased, and the stereoscopic impression of the audio-visual image and the separation degree of the sound are increased; Improved sound localization and layering.

The adjustment of the exciter requires the sound engineer to judge the sound quality and timbre of the system, and then adjust it according to the subjective hearing evaluation. Excitation is actually a kind of distortion. Poor control will make the sound more rough and scattered, and even increase the damage rate of the high-pitched unit of the speaker. Because of the high fidelity restoration of sound quality, most traditional spread spectrum systems do not need to add exciters.

compressor

Short for compression and limiter. Generally speaking, the compressor and limiter are mostly combined, and where there is compression function, there will also be limited amplitude function. Compressor: It is a processing device whose gain decreases with the increase of input signal level. Limiter: A processing device whose maximum output level remains unchanged no matter how the input level increases after the output level reaches a certain amplitude. The maximum output level can be adjusted as required. Using the pressure limiter has the following functions:

1. noise threshold

Because many processing equipment, microphones and a large number of long cables are often connected to large-scale sound reinforcement systems, it is easy to cause obvious background noise, especially in a quiet state (music stops playing and no one talks), and the noise may be obvious. Set a threshold level for the input signal through the noise gate on the voltage limiter, so that it will automatically "close the door" when no one speaks or no musical instrument is playing, but it will automatically "open the door" when someone speaks or the musical instrument begins to play, so as to avoid doing so.

2, safety protection, the role of the safety valve, the sound system may appear too high signal level due to improper operation (excessive volume control of equipment or improper operation of startup, shutdown, conversion, etc.), unstable signal (the difference of voice size of different singers or the change of the distance between microphone and mouth) or unexpected situation (strong sound feedback causes the microphone to drop or whistle), which will cause serious overload distortion to the system and even damage the speaker or power supply. After the pressure limiter is connected, the whole system can be protected through its compression and restriction functions, which is the main purpose of the widespread configuration of pressure limiters in theaters and dance halls.

3. Improving loudness compression and limiting the dynamic range of programs can suppress strong signals and improve weak signals. Because the sound intensity felt by people's ears is the average sound level in a certain period of time, some occasional high sound level peak signals in programs with low average sound level are not as loud as those in programs with high average sound pressure level without such peaks.

4. Using the compressor to produce special sound effects can produce special sound effects similar to "anti-sound" with shorter start-up time and longer release time, which is especially suitable for some percussion instruments. The signal level is quickly started and compressed immediately. When the signal naturally decays, the adjustment of release time increases its gain, thus reducing the degree of natural attenuation. This effect is very obvious for percussion instruments such as drums, especially for cymbals.

feedback exterminator

In the sound reinforcement system, if the volume of the microphone is greatly increased, the sound from the speaker will be transmitted to the microphone, causing howling, which is called acoustic feedback. Acoustic feedback not only destroys the sound quality and the scene atmosphere, but also makes the system signal too strong, thus burning out the power amplifier or loudspeaker (usually the tweeter unit of the loudspeaker). Before the feedback suppressor appeared, the sound recorder often used an equalizer to pull the feedback point (attenuate the feedback frequency) to suppress the acoustic feedback. The reason why the sound feedback occurs in the sound reinforcement system is mainly because some frequencies are too strong. Attenuating these too strong frequencies can solve this problem, but using equalizer to pull down will produce the following insurmountable shortcomings: First, the listening level of the sound recorder is extremely high. After the feedback occurs, the sound engineer must judge the frequency and degree of the feedback in time and accurately, and immediately and accurately attenuate this frequency point of the equalizer, which is difficult for inexperienced sound engineers to do. Second, it has a certain impact on the sound quality. The bandwidth of the existing 3 1 segment equalizer is 1/3 octave, and the bandwidth that some acoustic feedback needs to be attenuated is sometimes much less than 1/3 octave. At this time, many useful frequency components will be removed, which will cause irreparable loss to these frequency sounds. Third, it is possible to burn out the equipment during the adjustment process. It takes some time to judge the howling frequency with human ears. If this time is too long, the equipment will be damaged by being in a strong signal state for a long time. The above problems can be completely solved by using feedback suppressor, which can automatically detect the feedback frequency and accurately attenuate it. Some feedback suppressors can also shift the frequency and phase of feedback frequency points according to needs, so that the feedback suppression effect is better. This processing can not only effectively eliminate feedback, but also have no obvious impact on the playback quality, so its advantages are obvious.

Electronic frequency divider

The equipment for frequency division of weak audio signals is located in front of the power amplifier. After frequency division, each audio frequency band signal is amplified by its own independent power amplifier and then sent to the corresponding speaker unit. Easy to adjust, reduce power loss and interference between speaker units. Therefore, the signal loss is small and the sound quality is good. However, this method requires an independent power amplifier for each channel, which has high cost and complex circuit structure. Especially in the system with independent subwoofer, the subwoofer signal must be separated by electronic frequency divider and sent to the subwoofer amplifier.

In addition, there is another device on the market called digital audio processor. A device can also complete equalizer, voltage limiter, frequency divider, delay and other functions. The analog signal output by the analog mixer is input into the processor, converted into digital signal by the A-D converter, converted into analog signal by the D-A converter after processing, and transmitted to the power amplifier. Because of digital processing, in addition to independent equalization, the adjustment is more accurate and the noise figure is lower.