Some suggestions to avoid microphone howling
Why does the microphone produce feedback howling?
After the microphone is picked up, the sound is amplified by the mixer, peripheral equipment, power amplifier, and speaker. This sound enters the microphone through direct radiation or sound reflection, which generates positive feedback for the entire sound reinforcement system, causing the self-acoustic signal Excitation, the loudspeaker screams immediately, this phenomenon is called microphone sound feedback.
Microphone howling meeting: destroys the atmosphere of the entire sound reinforcement environment, makes the speaker or singer very embarrassed, makes the audience very disappointed, and even generates disgust; it has a great influence on the tweeter unit of the power amplifier or speaker, and it is easy to overload them Burned; due to the existence of acoustic feedback, the transmission gain and playback power of the entire sound reinforcement system are limited (that is, the volume cannot be increased).
Some suggestions to avoid microphone howling
1. Avoid placing the microphone in the radiation area of the speaker (at least not facing the speaker). After adjusting the level of a microphone, the microphone of the mixer is not balanced first, and the channel fader of the mixer is placed at 0 dB. Put the microphone in the main position on the stage, turn on the monitor output master (AUX) and gradually increase the output. After the microphone causes howling in a certain frequency band, fine-tune the AUX knob to stabilize the howling at a certain volume level, and then adjust the corresponding balance To eliminate the howling in this frequency band, and then continue to increase the volume. After the howling in another frequency band is generated, it can be eliminated by adjusting the equalizer, and so on. Wait until the mixer output level slider or AUX knob is adjusted to In the normal position (such as 0dB), the microphone no longer produces howling, OK, pull down the mixer fader. This method is used to find howling points that easily cause resonance in the sound field, and then appropriately reduce the level of the microphone channel, find someone to speak to the microphone, and then gradually increase the microphone volume to the normal position, if there are still howling, then Eliminated by the equalizer. Key points of operation: Be sure to control the level so that the howling can be maintained at a stable level and then adjusted to be more accurate. The operation must be slow, otherwise it will be impossible to find the correct howling points one by one. The resonance points in the room are generally around 5-6 points. If there are too many feedback points, you need to check whether the placement of the speakers is reasonable. After adjusting the monitor howling point, adjust the main sound reinforcement system in the same way. If the main sound reinforcement is a two-channel system, first turn off a channel, push the input fader of the mixer, and gradually increase the volume to find Howling point. After adjusting one channel, turn off this channel and adjust the other. After adjusting both sides, push the two channels up at the same time, check whether there are other howling points, and then eliminate them through the equalizer.
2. Choose a suitable microphone according to the actual situation, use a high-quality microphone as a reference, adjust the balance of the microphone input channel, use the microphone sound as close as possible to the high-quality microphone used for reference, after this step, the microphone sound is generally Can meet the requirements of most people, and then let the user test the microphone, according to the user's requirements, to make appropriate fine-tuning of the mixer channel balance.
3. Do a good job in the architectural design of the room to fully consider the problem of uniform absorption (reflection) of each frequency by the sound-absorbing material and sound-absorbing structure to reduce the inconsistency of sound reflection or absorption at different frequencies, especially in the space near the microphone, The sound reflection should be reduced as much as possible.
4. The connection between the equipment is firm to avoid the phenomenon of virtual welding (virtual welding or weak connection can cause instantaneous resistance increase and attenuation, unstable voltage)
5. The debugging equipment must be adjusted, and each equipment can not be in the critical working state, otherwise the signal will be unstable or oscillating.
6. A feedback suppressor or frequency shifter can be added to suppress and eliminate howling. After the original tone of the microphone is adjusted, you can add reverb, use the effector to select the appropriate effect type, turn on the corresponding AUX output of the mixer, and adjust the input level of the effector and the auxiliary output level of the mixer, and speak to the microphone. , To see if the signal output to the effector is too large or too small, generally control this signal to 0 dB. Set the mixing ratio of the effector to 100%, and then gradually increase the output level of the effector to check whether the level of the output callback console is normal. If it is normal, gradually increase the knob of the effector return. According to the user ’s requirements, Set the effect volume to the appropriate level. After the effect is added, due to the existence of artificial reverberation, a new howling point may be generated, and it is generally easy to appear the first howling point in the low frequency band. It is best to return the effect device to the line input of the mixer. You can adjust the balance of this input channel to eliminate howling.
The selection, debugging, installation, placement, etc. of audio equipment are very important for solving the howling problem, but solving the quality of the tuner, solving the equipment collocation error, and curbing the use of inferior equipment are also necessary to effectively solve the howling problem. Indispensable. Beilarly professional audio equipment manufacturer has been committed to the development and production of stage audio equipment, and has made a major breakthrough in professional audio. The company has a number of first-class construction and installation qualifications, we have a strong team that can solve the stage sound system solution on site, provide you with a professional and perfect stage sound solution, and try our best to solve the overall stage performance plan!
