The main points of operation of the tuner are the professional sounds currently used in domestic dance halls, most of which are imported equipment, and it should be said that the reliability is high. The main problem is that the professional qualities of the operators are not uniform, and there are few units that are really equipped with qualified tuner. Therefore, it often happens that the sound effect is not good due to improper operation, and even leads to equipment damage. This article explains the operation points of audio equipment in small and medium-sized dance halls, and can be used as a reference for formulating operation regulations. In addition, the self-excited howling phenomenon caused by microphone feedback in small and medium-sized singing and dancing halls is a common problem that causes headaches for users. Frequent howling will disappoint the guests, and the sound effects are impossible to talk about. In severe cases, it will cause equipment damage. Therefore, the self-excited howling phenomenon is an important issue in the use of dance hall audio, which are described separately below.
1. The sequence of turning on and off the audio equipment should be in order from front to back, that is, the audio source equipment (CD player, LD player, DVD player, recorder, video recorder), audio processing equipment (compressor, exciter, effect, Frequency divider, equalizer, etc.) to audio power amplifier to TV, projector, monitor. The order is reversed when shutting down, the power amplifier should be turned off first. This operation can prevent the impact of the device on and off, and prevent the amplifier and speaker from being burned.
2. Preparation before singing: debugging 1. The volume control potentiometer of the power amplifier is adjusted to the maximum position; the accompaniment music and microphone shunt fader on the mixer should be placed at 0dB; the GAIN input gain of each shunt on the mixer is placed in the adjusted position; tuning The total volume fader of the console is first placed at the minimum position (lower end); the sound quality compensation knobs of the mixer are all placed at the middle position.
2. Test the accompaniment channel, that is to say, use the CD or LD disc to play the song music, and look at the mixer's Jihiko jumper to the earth, to the level of ~ 6dB, at this time the singing voice and the accompaniment music are roughly the normal working volume ; But it should be noted that the volume should be moderate and sweet, too loud to make people tired and unbearable. The tuner should go to different locations in the hall to listen to the effect. Such as stereo sound image, music sound quality, etc. The track to be placed should be a familiar one, and the volume can be adjusted repeatedly (adjusting the gain of the branch GAIN) and the sound quality compensation of the branch until the sound effect is satisfactory. The requirements for musical effects should be strong and aesthetic, high-pitched sounds should not be harsh, and low-pitched sounds should not be turbid. The singing voice should be clear, for example, the female voice should be clear and audible. But it should not be too heavy. The shunt fader is set to 0dB, the total volume fader is set to 0dB, adjust the shunt GAIN input gain button to make the AU meter indicate about 0dB, and the system reaches the rated output power. But in normal operation, the total volume fader is usually adjusted to less than 6dB or less than 10dB, which is less than the rated output power.
3. Test the microphone channel. Generally, at least two microphone channels must be prepared. Try the microphone sensitivity and dynamic performance first, and then add reverb and accompaniment music to sing. After the reverb processing, the song should be more round, full and layered than the original song, with a sense of presence. Microphone volume adjustment: the shunt fader is set to 0dB, the microphone volume adjustment shunt GAIN input gain button, the shunt peak level indicator occasionally flashes as well, and the measurement of the total output power is indicated by the AU meter.
4. Trial adjustments for small bands, that is, the sound of microphones and electrical signals of various musical instruments, and sound proportion balance according to the style of the music.
5. The adjustment of the video image, that is, the projector and the color TV should make the image clear and colorful by adjusting the knobs such as brightness, contrast, color saturation, etc. The sound engineer should be able to use the DVD player and the karaoke device proficiently, and be familiar with the disk positions on the karaoke list. Note that when officially singing, you should press the D / A button on the DVD player. Eliminate the original singing sound.
3. Adjustment of audio processing equipment Room equalizer. The room equalizer has two functions. One is to adjust the sound quality to compensate for the unbalanced frequency response caused by the reverberation time in the hall. The other important function is to suppress a certain frequency band and suppress howling caused by acoustic feedback. The room equalizer should normally maintain the position set during the debugging of the sound project.
2. Compressor. In audio engineering, the compressor is also an important device, its role: one is to compress or limit the dynamic range of the program, prevent overload or distortion, and protect the power amplifier and the speaker; the other important role is to increase the program loudness Obviously feel it).
The adjustment data of the compressor is as follows:
(1) Noise gate GATE: The noise gate is closed when the indicator light is on, and the sound is low. Play a role in noise suppression. When the input signal falls to the threshold level, it starts to close, and the noise gate is generally placed between 0PEN and -20dB.
(2) Compression threshold level THRESHOLD: determines the level at which compression starts, generally set at -10 to 0dB, the gain decreases when compression starts, and the GAIN REDUOTION (dB) indicator starts to light.
Compression ratio RATT0: set to 2: 1;
Action time ATTACK: set to 10ms;
Release time RELEASE: set to O. 3s.
3. Reverb. Digital reverberators are currently widely used. Many different reverb effects are cured inside these machines for selection. The tuner should audition and rehearse the reverb effects of the used reverberator one by one, record the available programs, and use the in-machine keyboard at any time during tuning.
Four, tuning points (mainly to operate the mixer)
1. The cabaret tuner works in the control room. When tuning, the monitor monitor speakers and monitor earphones should be used to monitor the main channel and the return channel respectively. The tuner should be familiar with the relationship between the monitoring sound and the live sound. The sound quality adjustment depends largely on the individual's hearing.
2. Use compressors and exciters to increase the loudness and beauty of the sound. The adjustment of the exciter mainly depends on hearing, and the sound should be adjusted to be full and sweet according to the instruction manual of the device.
3. Beautify singing with reverb. For non-professional singers, the reverberation should be appropriately increased to cover up the defects in noise and vocalization.
4. When the volume is low, pay attention to increase the low frequency and high frequency; when the volume is high, increase the middle frequency appropriately to enhance the brightness of the sound.
5. The tuning is dominated by singing. Before singing, the accompaniment is gradually lowered to highlight the singing. The low frequency should be attenuated by 3 ~ 5dB, the high frequency above 7kHz should be attenuated by 3dB, and the mid and low frequency can be increased near 200Hz to increase the intensity, and the 2 ~ 4kHz can be obviously increased by 3-6dB. For disco or rock music, it is necessary to increase the low frequency (40? 100Hz) and high frequency (7? 20KHz) greatly.
6. When boosting the bass, you must not turn the compensation button violently to avoid damage to the amplifier and speakers due to excessive power output. The same is true for the low frequency adjustment of the equalizer.
7. If there is audible feedback howling, you should quickly pull down the total volume fader of the sound console to remove the howling, find out the reason and then gradually push it up.
8. When the main channel fails and cannot be broadcast, the rotation angle of the return listening speaker can temporarily replace the main channel, so that the singing can continue. Microphones used for singing should have a backup, which can be replaced when the microphone is silent. The DVD player should also have a backup, which can be replaced when the DVD player fails.
5. Suppression of acoustic feedback (howling) 1. The self-excited howling caused by microphone acoustic feedback is a common phenomenon in karaoke halls and karaoke halls. Due to the presence of acoustic feedback, the gain of general sound reinforcement systems cannot be great. The reasons for the occurrence of acoustic feedback howling are:
(1) The microphone is too close to the speaker, and the microphone is directed towards the speaker;
(2) The reverberation on the mixer is too large;
(3) The microphone volume is adjusted too large;
(4) The compressor is not connected;
(5) Acoustic design defects in the hall.
2. For the above reasons, the following measures can be taken:
(1) Define a general range for the singer's activity stage, and howling should not occur within this range. In other words, the singer should not be too close to the main speaker, and the main speaker should be symmetrical on both sides of the stage; the singer's position should not point the microphone directly toward the speaker.
(2) The stage of the cabaret should be acoustically treated, and sound absorption materials should be installed on the walls and sides.
(3) Turn on the compressor, the compression ratio should be set to <= 2: 1, the action time is 10ms, and the release time is 0.3s.
(4) Do not turn the reverberation adjustment and volume on the mixer too high.
(5) When the above measures are not effective, the frequency that is prone to howling can be attenuated by adjusting the equalizer. The specific operation method is as follows:
Record the position of each frequency point of the equalizer first; then, demonstrate. Increase the volume (adjusted with the mixer's total fader) to the position where the system just generates self-excitation, and adjust the adjustment knob on the equalizer one by one starting from low frequency, which can effectively eliminate the frequency of self-excitation howling, according to general experience There is only one self-excited resonant frequency (such as 250Hz), which can be pulled down by 3 to 5dB around this frequency, and the remaining frequency points should still maintain the original recorded position.
This method can effectively suppress acoustic feedback, but it cannot take into account the music effect. Through adjustment, the amplification gain can have a stable margin of 5-6dB, which is necessary for the system to work stably.
(6) If the above measures still do not work, consider installing an acoustic feedback suppressor. For example, the frequency shifter can effectively overcome the acoustic feedback, so that the gain of the gain can be stabilized by 5,6.
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