First, the audio equipment on and off sequence
It should be turned on in order from front to back, that is, by sound source equipment (CD player, LD machine, DVD player, recorder, video recorder), audio processing equipment (compressor, exciter, effect, frequency divider, equalizer, etc.) To the audio power amplifier to the TV, projector, monitor. When the shutdown is reversed, the amplifier should be turned off first. This operation can prevent the impact of the device from being turned on and off, and prevent the amplifier and the speaker from being burnt.
Second, preparation before the concert - debugging
1. The volume control potentiometer of the amplifier is always adjusted to the maximum position; the accompaniment music and microphone split fader on the mixer should be set to 0dB; the GAIN input gain of each branch on the mixer is placed in the adjusted position; tuning The total volume fader is placed in the minimum position (lower end); the mixer sound quality compensation knob is placed in the middle position.
2. Test the accompaniment channel, that is, use the CD or LD to put the song music, and the mixer will jump into the earth, and the sound will be around 6dB. At this time, the singing and accompaniment music is roughly the volume during normal work. But pay attention to the volume to be moderately pleasing, too loud and easy to make people tired and unbearable. The tuner should listen to the results in different locations within the hall. Such as stereo sound image, music quality and so on. The placed track should be a familiar song, which can be adjusted repeatedly (by adjusting the GAIN gain) and the split sound quality compensation until the sound is satisfactory. The requirements for the effect of music should be strong and aesthetic, the treble can not be harsh, the bass can not be turbid, the song is required to be clear, such as the voice of the female voice is clear and audible. But not too heavy. The split fader is placed at 0 dB, the total volume fader is set to 0 dB, and the GAIN input gain knob is adjusted so that the AU meter indicates about 0 dB, at which time the system reaches the rated output power. However, in normal operation, the total volume fader is generally adjusted to below -6dB or -10dB, which is less than the rated output power. Welcome to Home Theater Network
3. Test the microphone channel. In general, at least two microphone channels must be prepared. Try the sensitivity and dynamic performance of the microphone first, then add the reverb and accompaniment music to sing. The song will be reverberated and should be more rounded, fuller and more layered than the original song. Microphone volume adjustment: The split fader is set to 0dB, the microphone volume adjustment split GAIN input gain button, and the split peak level indicator is occasionally flashed as well. The total output power is measured by the AU meter.
4. The audition adjustment of the small band is performed on the microphone sounding and electric signals of various instruments, and the sound ratio is balanced 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 its brightness, contrast, color saturation and other knobs. The sounder should be able to use the DVD player and the karaoke machine skillfully, and be familiar with the position on the song list. Note that in the official singing, you should press the D/A button on the player. Eliminate the original singing voice.
Third, the adjustment of audio processing equipment
1. Room equalizer. The room equalizer has two functions. One is to adjust the sound quality to compensate for the imbalance of the frequency response caused by the reverberation time in the hall. The other important function is to lower a certain frequency band and suppress the howling caused by the acoustic feedback. The room equalizer should always be in the position set during the sound engineering debugging.
2. Pressure limiter. In sound engineering, the compressor is also an important device. Its function is to compress or limit the dynamic range of the program, to prevent overload or distortion, and to protect the amplifier and the speaker. Another important role is to improve the loudness of the program (this can be relied on by hearing. Obviously felt).
The adjustment data of the compressor is as follows:
(1) Noise gate GATE: When the indicator is on, the noise gate is closed and the sound is small. Plays a role in squelch. When the input signal drops to the threshold level, it begins to turn off, and the noise gate is generally placed between 0PEN and -20dB.
(2) Compression threshold level THRESHOLD: Determines the level at which compression starts, usually at -10 to 0 dB. When the compression starts, the gain decreases, and the GAIN REDUOTION (dB) indicator starts to light.
Compression ratio RATT0: placed at 2:1;
Action time ATTACK: placed at 10ms;
Release time RELEASE: placed in O. 3s.
3. Reverb. Digital reverberators are widely used today. This type of machine internally solidifies many different reverb effects to choose from. The tuner should audition the various reverb effects of the reverb used, and record the available programs. You can use them in the machine at any time during tuning.
Fourth, the tuning points (mainly operating the mixer)
1. The karaoke adjuster works in the control room. When tuning, you should use the monitor monitor and monitor headphones to monitor the main channel and the return channel respectively. The tuner should be familiar with the relationship between the monitor sound and the live sound, and the sound quality adjustment depends largely on the individual's hearing.
2. Use a compressor and an exciter to increase the loudness and aesthetics of the sound. The adjustment of the exciter is mainly based on hearing, and the sound should be adjusted to be full and pleasing according to the instruction manual of the equipment.
3. Beautify the song with reverb. For non-professional singers, the reverberation should be appropriately increased to cover up the noise and vocal defects.
4. When the volume is small, pay attention to raising the low frequency and high frequency; when the volume is large, increase the intermediate frequency appropriately to enhance the brightness of the sound.
5. The tuning is dominated by singing. Before the song appeared, gradually lower the accompaniment to highlight the song. The low frequency should be attenuated by 3-5dB, the high frequency above 7kHz should be attenuated by 3dB, the middle and low frequency can be increased by 200Hz, and the 2-6kHz can be increased by 3-6dB. For disco or rock music, pay attention to the high frequency (40-100Hz) and high frequency (7-20KHz).
6. Do not slam the compensation button when raising the bass 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 the sound feedback whistling sound occurs, the total volume fader of the sound station should be quickly pulled down to remove the howling sound, and then the reason is gradually pushed up.
8. When the main channel fails and cannot be delivered, the rotation angle of the returning speaker can be temporarily replaced by the main channel, so that the singing can continue. The microphone for singing should have a backup, and the backup can be replaced when the microphone is silent. The DVD player should also have a backup, which can be replaced by a backup when the DVD player fails.
Fifth, the suppression of acoustic feedback (howling)
1. The self-excited howling caused by the microphone sound feedback is a common phenomenon in the karaoke and karaoke halls. Due to the acoustic feedback, the general amplification system gain cannot be large. The reason for the acoustic feedback whistling is:
(1) The microphone is too close to the speaker, and the microphone is pointing to the speaker;
(2) The reverberation adjustment on the mixer is too large;
(3) The microphone volume adjustment is too large;
(4) The pressure limiter is not turned on;
(5) Defects in acoustic design in the hall.
2. The following measures can be taken for the above reasons:
(1) A general range is defined for the singer's event stage, and no whistling sound should occur within this range. In other words, the singer should not be too close to the main speaker, the main speaker should be symmetrical on both sides of the stage; the singer's position should not cause the microphone to point forward to the speaker.
(2) The stage of the karaoke room shall be acoustically treated, and sound absorbing materials shall be installed on the wall 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) The reverb adjustment and volume on the mixer should not be too large.
(5) When the above measures are not effective, the frequency that is easy to produce 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 the performance. Increase the volume (adjust 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 from the low frequency, which can effectively eliminate the frequency of self-excited howling, according to experience There is only one self-excited resonant frequency (such as 250Hz), which can be pulled down by 3-5dB near this frequency, and the remaining frequency points should remain the original recorded bits.
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