Various activities planned in the audio equipment sound practice, Small electronic products wholesale sound engineer worked out a lot of feedback inhibition of the stage sound system sound way to build the sound stage set up in Shenzhen when the experts will take some effective measures to eliminate the acoustic feedback; and electro-acoustic research and development experts have a variety of electro-acoustic devices to reduce the acoustic feedback phenomenon. Practical application of these measures, and achieved good results.
Stage lighting and sound equipment rental center experts introduce you to simply suppress, reduce or eliminate acoustic feedback method.
First, the speaker's microphone in the sound is not easy to spread
To make the speaker sound stage, the sound is not easy to spread to the microphone in order to reduce the likelihood of acoustic feedback phenomenon, mainly take the following measures.
(1) microphone away from speakers. This approach is difficult to achieve in the dance hall venue, because the area of dance halls are generally not large. But in theater, the opening ceremony on-site lighting or large stage performances, this method will have a role, for example, consider the microphone hanging above the band or stage lighting used in the title of the shelves for pickup, the microphone so we can guarantee close enough from the sound source can also be as far as possible away from the microphone and speaker.
(2) the use of directional speakers and microphone. The use of speakers and microphone directivity to suppress acoustic feedback howling, often also play a role from time to time, if the location is not using the microphone speaker sound radiation area, the speaker sound is not easily spread to the microphone in; another aspects in the use of directional transmission device, do not let being speakers, try to avoid acoustic feedback. Stage set up in the beginning, you need to take into account the speaker's point of view can be adjusted so that the speaker's sound radiation area as the playback area is not in concert speaker, and microphone not working on the speaker.
(3) The appropriate reduction in the volume of the microphone channel. This pickup will be limited or band concert, performance results were affected. But sometimes sound engineer had to take this to reduce the volume of the worst. According to performance conditions, such as real-time control volume, when ringing occurs, the tuner to pull down the volume a timely manner to avoid whistle. When the actor holding or wearing the microphone through the speakers before, they should also pay attention to control the volume, otherwise it will cause whistle.
(4) If the mixer parametric equalizer with a Q-value adjustment, compensatory measures can be taken to the volume, the sound of audio equipment, access to appropriate compensation is: the equalizer audio frequency band transferred to the microphone pickup range of the band, will this band to enhance the process, before the emergence of whistle stop.
Second, the elimination of the equipment
Eliminate the acoustic feedback, but also by the sound signal processing to solve, all the electro-acoustic equipment manufacturers and leasing businesses have a variety of sound can inhibit the acoustic feedback of the sound equipment, which has a good acoustic feedback suppression results described below several major equipment.
(1) frequency shifter. This is a voice can change the frequency of equipment, works similar to the pitch shifter, it can increase the frequency of the sound signal is 5Hz, damage resulting acoustic feedback conditions, thus inhibiting the acoustic feedback. However, the use of the device has some limitations, the use of sound in the language to make up the equipment to good effect, the destruction of sound small, but instrumental music in concert and there will be significant use of voice modulation feeling . This is because the language of the lower frequency range is between 130 ~ 350Hz, 5Hz pitch change will not only make it clear the feeling tone becomes higher, but in vocal and instrumental music around the lower limit frequency of 20Hz, 5Hz tone changes clearly aware of the human ear has been out.
(2) equalizer and feedback reducer. Both devices can be effectively attenuated the gain of the feedback frequency (pull feed point), the sound reinforcement system are the result of feedback, because the system in some of the frequency signal is too strong, too strong if the attenuation of these frequencies can be suppressed acoustic feedback. Equalizer and feedback suppressor difference is that the equalizer need to whistle frequency manually pull down the feed point; and automatic feedback suppressor can be found in the frequency and attenuation of acoustic feedback down, attenuation bandwidth and attenuation amount by the machine to decide the actual situation, almost no any impact on sound quality, but also to make the microphone pick up the sound becomes nice.
(3) limiter. Compressor is based on the input signal strength automatically changes the output signal amplification (gain) of equipment. Used to suppress acoustic feedback when the compression ratio can be transferred to ∞: 1 (At this point it as a limiter), the feedback will be transferred to the critical point threshold. Thus, when a large volume to the forthcoming acoustic feedback, the sound intensity exceeds the threshold, the intensity will not continue to increase and, therefore, does not produce a sound feedback. But with the pressure limit will bring the sound of acoustic feedback suppression dynamic losses.