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Try different ways to solve the whistle of the microphone

When the microphone for live PA, there will be a microphone whistling problems (line signal positive feedback caused by Cheap Beats By Dre self-excited howling this is not discussed), popular point that this is when the voice signal is sent from the speaker and then re-enter from the microphone To amplify the system after another amplification, the formation of signal overlay, there are positive feedback to produce howling, acoustic workers have been trying to use a variety of ways and equipment to solve this problem, but not very satisfactory, based on my own experience There are several ways to summarize, we can choose to try:

1. Feedback suppressor: Its working principle is to appear in the signal more obvious several or a dozen more than the default value of the level of frequency suppression, so as to achieve the purpose of suppressing howling, this method Fixed microphone placement and conference amplification still have some effect, but the performance is not good at the stage or even produce the result of disrupting the performance, because the stage is performed in different parts of the actor is kept moving, right Frequency tracking is very difficult, followed by performers in the concert (especially those rock singers) dynamic is great, so that many of the frequency level value is not overwhelmed by howling, this time the feedback suppressor will mistakenly think A whistle appeared, and suppressed these frequencies, resulting in a collapse of the sound pressure, undermining the normal performance of the effect.

2. Frequency shifter: it works on the frequency of the microphone signal up or down a few or dozens of frequency points, to achieve the purpose of not generating positive feedback, this approach is also only suitable for conference speaker When used as the effect of the frequency change produced by the frequency shifter can be very funny and will make it impossible for anyone to find North.

3. Automatic Mixing Console: It works by using automatic delay noise gate, the signal input and no signal input microphone on / off processing to achieve the purpose of eliminating howling, this method is very suitable for use in the microphone The use of a large number of meeting venues in the stage of the language programs can also be used, but the song is not performing well (for reasons, see the noise gate).

4. Noise gate: It works by using the threshold level on the microphone signal on / off processing, to eliminate the purpose of howling, this method is generally used in the drum pick up (with the drum source pickup method Not in this column), only when the drums, the microphone will be turned on to prevent the Beats By Dre Sale stage back to listen to the speakers and drum pickup microphone positive feedback signal and howling, used in song and dance programs are not good, because there The program actor's voice is very light, this time because the noise level does not reach the door threshold noise level will not lead to the scene "lost."

5. Compressor: It works is that when the signal exceeds the set level, the compressor began to compress the signal proportional to prevent the signal continues to expand to eliminate the whistle of the purpose, this approach can be used on the stage But it was incapable of beginning to appear howling at the set level.

6. Graphic Equalizer: It works by attenuating or cutting off some frequencies of howling so as to prevent whistling. However, its disadvantage is that the setting of frequency is fixed and the frequency of whistling appears The point is not fixed, it may appear in the first three quarters of the two frequency or 1/2 or after the 3/4 ... ... so sometimes the adjacent two frequencies must be attenuated, then the icon Equalizer bandwidth is relatively large, or cut off some of the frequency cut will result in frequency collapse and distortion, so the graphic Beats By Dre Cheap" href="/">Beats By Dre Cheap equalizer is only suitable for use in some of the less demanding amplification occasions.

7. Parametric Equalizer: It works by sweeping the sweeper to the frequency of howling and adjusting the bandwidth at that point, then decaying or cutting the point to achieve both howling suppression and usefulness The signal is not attenuated or cut off, so the parametric equalizer, more suitable for a variety of occasions.

These are some of my experience to eliminate howling, of course, but also based on the actual situation to decide, including the test, I suggest not to use a dedicated test microphone whistle-point test, but with live microphone test, because the actor is It is impossible to test the microphone to sing, and other methods like connection, etc., is also required practice, I usually use the way is: parametric equalizer + compressor connected to the microphone input path breakpoint (a set of each microphone ), Drum channel + noise gate, of course, need more equipment to invest more capital, we can choose according to their own specific circumstances and the use of equipment (and perhaps better methods).

About the chest mark (collar clip microphone) easy to whistle This is the chest mark and the pickup level of the pickup level, the general direction of the chest mark pickup is relatively wide (omnidirectional or fan-shaped) and chest mark The use of the clip is usually clipped to the chest or the collar on the actor's mouth far so the output level of the chest mark and the mixer input level of the road are relatively large pick, so the chest mark howling The possibility is relatively large, if this situation can be slightly above the level of the two places a little smaller, not only to ensure the performance without whistling can be, in addition, the previously mentioned chest Mark pickup point , And some chest mark is used for conferences and teaching its mark is generally electret mark is small, this chest mark is never used for stage performances it out of the human voice is distorted and the easiest Xiao Called, and the stage show beats solo with a chest mark is capacitive or moving coil, there is no distortion nor so easy howling.