The role of feedback suppressors in conference sound system

In this lesson, we'll talk about the role of the response presser in the conference sound system. In the sound amplification system, if the volume of the microphone is increased greatly, the sound announced by the speaker will be transmitted to the whistle caused by the microphone. This phenomenon is the sound response. The existence of sound reaction not only destroys the sound quality, restricts the expansion volume of the microphone sound, so that the sound picked up by the microphone can not be well reproduced; the depth of sound reaction will also make the system signal too strong, and then burn the amplifier or speaker (usually burning the loudspeaker head), resulting in loss. Therefore, once the sound amplification system presents the phenomenon of sound reaction, we must try to prevent it, otherwise, it will cause endless harm.

Whether or not the acoustic response can be eliminated is an important indicator of a sound engineer's skill level. Before the reaction is presented by the press, the sound engineer usually selects the method of equalizer pulling feed point (attenuating the response frequency) to press the response. The main reason why the sound reaction occurs in the sound reinforcement system is that the sound of some frequencies is too strong. If these frequencies are attenuated, the problem can be solved.

1, it is possible to burn equipment in the process of adjustment. It is necessary to use the human ear to determine the frequency of the scream. Assuming that the time is too long, the equipment will be damaged because it is in a strong signal condition for a long time. This problem can be thoroughly dealt with by using the reaction press, that is, the reaction can be effectively eliminated without affecting the playback quality, so its advantages are obvious.

2, there is a definite effect on the quality of replaying. The bandwidth of the existing 31-segment equalizer is 1/3 octave, and sometimes the attenuation bandwidth required by some acoustic response is far less than 1/3 octave. At this time, many useful frequency components will be removed, resulting in irreparable loss of these frequency sounds.

3. The sound level of the acoustician is very high. It is necessary for the acoustician to distinguish the frequency and degree of the reaction in time and accurately after the reaction, and to attenuate this frequency point of the equalizer immediately and accurately, which is difficult for the experienced acoustician.

Reaction presser is a kind of equipment which pulls the feeding point actively. When the acoustic response occurs, it will find and calculate its frequency and attenuation immediately, and fulfill the instructions of the response according to the calculation results. Its bandwidth can be set to 1/60 octave, so the phenomenon of affecting other frequencies in the process of acoustic response pressing is greatly reduced, and the effect of equalizer pressing is greatly improved. In the past, the response regulator was immature because of its early development. There is a certain problem in function and design, and its application is not very satisfactory.

Restrain whistling and create perfect meeting space

Early understanding of the damage caused by howling, so how to restrain the occurrence of howling? Howling caused by acoustic response is a skill problem that all sound reinforcement systems meet and are difficult to handle. The conference system is more prominent because of the large number of microphones in the same room. At present, there are a lot of methods to adopt the press-to-sound response skills, but there is still no one is absolutely perfect, generally adopt a variety of methods combined.

First, "speaker active switch" and "microphone active switch" skills.

1. Hand-held conference system: when speaking to a certain microphone, the speaker of the same unit is closed actively; and when the microphone of this unit has no signal, the speaker of the same unit is open actively. If the microphone key 30s is not pressed, the microphone of the unit will also be closed.

2. Active Mixed Conference System: When speaking to a microphone, the microphone is open and closed when not speaking.

More advanced conference systems have more built-in adjustable equalizers and whistle controllers. Panasonic's WM series conference system's main control computer also imitates the design of the general mixer, equipped with SEND / RETURN (send / return) interface, users can use external parametric equalizer or frequency shifter and other audio processing equipment when required, to facilitate more detailed control of the sound signal to scream and improve the sound quality.

Two. Variable directional microphone and 4-ECM microphone skill.

It is proved theoretically and practically that the selection of microphones with different directional characteristics in different acoustical environments is conducive to increasing the transmission gain and responding to screaming in accordance with the percussion. General experience: Heart-shaped microphones are preferred in places with better acoustical conditions, such as lectures and stages; heart-shaped or super-heart-shaped microphones are preferred in round tables; and speakers are seated in particularly harsh acoustic environments, such as long reverberation times or long speaker-spaced microphones (such as Leaders'interviews or various "forums" etc.). The sofa and microphone are placed on the coffee table. The super heart shape and super directional microphone can be selected.

Reaction presser is a kind of sound equipment which pulls the feeding point actively. When the sound reaction occurs, it will find and calculate its frequency and attenuation immediately, and fulfill the instructions according to the calculation results. Its bandwidth can be set to 1/60 octave, so the phenomenon of affecting other frequencies in the process of acoustic response pressing is greatly reduced, and the effect of equalizer pressing is greatly improved. In the past, the response regulator was immature because of its early development. There is a certain problem in function and design, and its application is not very satisfactory.