The sound system of the microphone pickup has the possibility of feedback whistling. There is a high risk of whistling in the microphone, which is mainly expressed in the following aspects:
1. The power amplifier generates a large power output when it is self-excited, which may exceed the tolerance of the sound reinforcement equipment and burn out the power amplifier and sounding equipment.
2. When the feedback coefficient is close to 1, because of the comb filtering effect, the superposition of the delayed sound field and the direct sound will make the sound field narrower than the original sound field.
3. The delay feedback of the sound field of the loudspeaker will cause the delay response of all the systems to form a continuous string, and this kind of response will aggravate the comb filtering effect, resulting in a distorted reverberation tailing - just ringing true.
4. The sound pressure output during the howling is very large, which seriously affects the atmosphere of various activities.
The feedback whistle should start from the premise of generating feedback whistling, as long as it can smash one of the premise, the goal can be achieved.
First, the adjustment interval method
One of the most effective preparations for avoiding whistling and promoting the volume of the amplified sound is to pick up the microphone as close as possible to the sound source, while the microphone should utilize non-directionality. It is understood here that the directional microphone (especially the sharp directional microphone) has a small pickup attenuation of the far-distance sound source, and the adjustment interval has little effect on the promotion of the amplification volume and the avoidance of howling. Whether the sound reinforcement system is easy to whistle is not directly related to the activity of the microphone. Only the microphones that are not too high in activity are sharply directional, and it is easy to produce whistling. Shortening the interval between the vocal device and the listener can actually promote the loudness of the amplified sound. The total gain of the system can be appropriately reduced. If it is supplemented by a near-field speaker with wide directivity, the microphone can be avoided from the far point.
For the direct feedback sound field of the speaker, the farther the microphone is from the speaker, the better the speaker is as close as possible to the listener. The microphone should be placed on the back of the target of the loudspeaker's radiation target. If the microphone is likely to be moved around, the speaker should be placed in a location where the microphone can't be very close.
Second, the frequency equalization method (wideband notch method)
Because the frequency curve of the microphone pickup and sounding equipment is not a straight line of ambition (outside is some poor quality playback equipment), and the acoustic resonance of the auditorium sound field, the frequency response fluctuates greatly. The frequency equalizer can be used to compensate the sound reinforcement curve, and the frequency response of the system is adjusted to an approximate straight line, so that the gain bases of the respective frequency bands are consistent, and the sound transmission gain of the system is improved.
An equalizer of 21 or more segments should be used, and a parameter equalizer should be constructed in a place with higher requirements. When the requirement is higher, a feedback button can be adopted. In fact, when the sound reinforcement system presents feedback self-excitation, its frequency is only a pure tone fixed at a certain point. Therefore, as long as the frequency is cut off by a narrow-band trap, the system can be squeaked.
Third, the feedback press method (narrow band notch method)
In high-demand occasions, such as some live singing venues, using audio feedback to actively assemble, this type of assembly can actively track the feedback point frequency, actively adjust the Q-value bandwidth, actively dissipate the acoustic feedback and maximize the shelter. Sound quality. The reason is that it is whistling through the trap. For example, Sabine's FBX series feedback push-button device is a 9-segment narrow-band active compression limit assembly controlled by microcomputer. It can better distinguish the feedback self-excited signal and the music signal, which can be used when the system is self-excited. Agile reacts and sets a very narrow digital filter at the feedback frequency. The notch depth is also actively set, and the filtering bandwidth is only 1/3 octave. Such a narrow notch band is close. It does not affect the loudness and tone.
1. The power amplifier generates a large power output when it is self-excited, which may exceed the tolerance of the sound reinforcement equipment and burn out the power amplifier and sounding equipment.
2. When the feedback coefficient is close to 1, because of the comb filtering effect, the superposition of the delayed sound field and the direct sound will make the sound field narrower than the original sound field.
3. The delay feedback of the sound field of the loudspeaker will cause the delay response of all the systems to form a continuous string, and this kind of response will aggravate the comb filtering effect, resulting in a distorted reverberation tailing - just ringing true.
4. The sound pressure output during the howling is very large, which seriously affects the atmosphere of various activities.
The feedback whistle should start from the premise of generating feedback whistling, as long as it can smash one of the premise, the goal can be achieved.
First, the adjustment interval method
One of the most effective preparations for avoiding whistling and promoting the volume of the amplified sound is to pick up the microphone as close as possible to the sound source, while the microphone should utilize non-directionality. It is understood here that the directional microphone (especially the sharp directional microphone) has a small pickup attenuation of the far-distance sound source, and the adjustment interval has little effect on the promotion of the amplification volume and the avoidance of howling. Whether the sound reinforcement system is easy to whistle is not directly related to the activity of the microphone. Only the microphones that are not too high in activity are sharply directional, and it is easy to produce whistling. Shortening the interval between the vocal device and the listener can actually promote the loudness of the amplified sound. The total gain of the system can be appropriately reduced. If it is supplemented by a near-field speaker with wide directivity, the microphone can be avoided from the far point.
For the direct feedback sound field of the speaker, the farther the microphone is from the speaker, the better the speaker is as close as possible to the listener. The microphone should be placed on the back of the target of the loudspeaker's radiation target. If the microphone is likely to be moved around, the speaker should be placed in a location where the microphone can't be very close.
Second, the frequency equalization method (wideband notch method)
Because the frequency curve of the microphone pickup and sounding equipment is not a straight line of ambition (outside is some poor quality playback equipment), and the acoustic resonance of the auditorium sound field, the frequency response fluctuates greatly. The frequency equalizer can be used to compensate the sound reinforcement curve, and the frequency response of the system is adjusted to an approximate straight line, so that the gain bases of the respective frequency bands are consistent, and the sound transmission gain of the system is improved.
An equalizer of 21 or more segments should be used, and a parameter equalizer should be constructed in a place with higher requirements. When the requirement is higher, a feedback button can be adopted. In fact, when the sound reinforcement system presents feedback self-excitation, its frequency is only a pure tone fixed at a certain point. Therefore, as long as the frequency is cut off by a narrow-band trap, the system can be squeaked.
Third, the feedback press method (narrow band notch method)
In high-demand occasions, such as some live singing venues, using audio feedback to actively assemble, this type of assembly can actively track the feedback point frequency, actively adjust the Q-value bandwidth, actively dissipate the acoustic feedback and maximize the shelter. Sound quality. The reason is that it is whistling through the trap. For example, Sabine's FBX series feedback push-button device is a 9-segment narrow-band active compression limit assembly controlled by microcomputer. It can better distinguish the feedback self-excited signal and the music signal, which can be used when the system is self-excited. Agile reacts and sets a very narrow digital filter at the feedback frequency. The notch depth is also actively set, and the filtering bandwidth is only 1/3 octave. Such a narrow notch band is close. It does not affect the loudness and tone.
Solar Home Lighting System Kit
SHENZHEN CHONDEKUAI TECHNOLOGY CO.LTD , https://www.szsiheyi.com