The sound system that picks up the microphones has the possibility of feedback howling. The harm of microphones whistling is significant, mainly manifested in the following aspects:
1. When self-excited, the power amplifier will produce a large power output, which may exceed the capacity of the sound reinforcement equipment and burn out the power amplifier and sound producing equipment.
2. When the feedback coefficient is close to 1, due to the comb filtering effect, the superposition between the delayed sound field and the direct sound field will cause the amplified sound field to be less than the original sound field
Narrowing in sound sense.
3. The delayed feedback of the speaker sound field will cause a series of delayed echoes throughout the entire system, and this echo will exacerbate the comb filtering effect, resulting in significant
Distorted reverberation, trailing sound, and just sound distortion.
4. The sound pressure output during whistling is very high, which seriously affects the atmosphere of various activities.
Eliminating feedback howling starts with the necessary conditions for generating feedback howling. As long as one of these conditions can be broken, the goal can be achieved. Here are the top 5 recommended by Guoshi
A method to eliminate microphones feedback howling
1. Eliminating microphones feedback howling using inverse cancellation method
Anti phase cancellation to prevent self-excitation is common in high-frequency amplification circuits. Two microphoness of the same specification can be used in the audio amplification circuit to pick up direct sound and reflected sound, respectively,
By using a reverse phase circuit to cancel out the reflected sound signals before entering the power amplifier, it can effectively prevent self excitation of whistling
2. Adjusting the distance method to eliminate microphones feedback howling
One of the most effective ways to avoid whistling and increase the amplification volume is to pick up the microphones as close as possible to the sound source, while using a non directional microphones. here
To be clear, directional microphoness (especially sharp directional microphoness) have very little pickup attenuation from distant sound sources. Adjusting the distance plays a role in increasing the amplification volume and preventing whistling
Not big. Whether the sound reinforcement system is prone to howling is not directly related to the sensitivity of the microphones. However, highly sensitive microphoness are highly directional and prone to squealing
It's just that. Shortening the distance between the sound equipment and the audience can actually improve the loudness of the amplification. The total gain of the system can be appropriately reduced. If accompanied by broad directional
A near field speaker, with the microphones slightly away from the speaker, can avoid howling
For the direct feedback sound field of speakers, the farther the microphones is from the speaker, the better, and the closer the speaker is to the audience, the better. The microphones should be placed in the radiation direction of the speaker
On the back, if the microphones is likely to be carried around, the speaker should be placed in a place where the microphones cannot be very close
3. Phase modulation method to eliminate microphones feedback howling
The self-excited howling of the amplifying system has a positive feedback loop. If the microphones signal is phased, it will disrupt the phase condition of self-excited howling, thereby preventing the system from self excitation
Screaming. There is data indicating that the stability is best when the phase deviation value is 140 °; Moreover, the higher the modulation frequency, the better the stability of the system. To facilitate processing
The subsequent sound quality does not experience significant distortion, and the maximum allowable value of its phase modulation frequency is 4Hz. Finally, after adjusting various equipment, never let others move around,
Including some DJs who are not familiar with equipment performance and only know how to turn it on, off, and adjust the volume
4. Feedback suppressor method (narrowband notch method) to eliminate microphones feedback howling
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