Specific steps and precautions for on-site debugging of stage sound
/舞台音响现场调试具体步骤与注意事项
Specific steps and precautions for on-site debugging of stage sound
2020-04-301911
The on-site sound debugging is a huge system engineering, especially in the sound reinforcement system of large-scale performance, the sound mixer must have rich on-site experience, macro and clear system thinking, excellent courage and steady state of mind, as well as meticulous and rigorous work habits. We should not only pursue every correct operation, but also master the rhythm of the whole activity, use our passion and solid professional skills to call out our own style, and combine the characteristics of each program to mobilize the atmosphere on site.
Therefore, as a tuner, he must be familiar with the principles of acoustics and electricity, the types and structures of music in various countries, and the most important thing is to be able to correctly understand the different emotions expressed by various kinds of music.
First of all, the tuner should arrive at the site early, check the line connection carefully according to the system line drawing, and confirm that the line can operate normally. Set the power amplifier input to the minimum, and set the input and output knobs of all peripheral devices to the 0 dB position or the middle position. Power on the amplifier according to the sequence from the front level to the back level (do not turn on the power amplifier first), and power on the power amplifier after checking that all devices are powered on normally. At this time, properly turn on the gain control of the power amplifier, play a familiar CD, and adjust the input level of the mixer to the basic normal position. Slowly push up the mixer push, listen to whether the sound from the speaker is normal, whether it is distorted, if not, shut down and check immediately.
After the system is basically normal, turn on the power supply of all equipment, set the power amplifier level at the maximum, pull down the output push of the mixer, connect the phase meter generator to the input channel of the mixer, turn on the power supply of the phase meter to adjust the output gain and the input gain of the mixer to 0 dB of the indicator of the mixer. Slowly push up the output push of the mixer. When the "bang" sound in the speaker reaches enough loudness, use the phase detector to check whether each speaker is in phase or consistent with the description in the speaker manual. It is better to turn off other speakers to prevent interference during detection, and the detection is more accurate one by one. If there is any abnormality, check whether the speaker line is connected reversely or whether the system connection line is reversed. It can be adjusted or replaced before testing.
If the combination of ultra-low frequency and full frequency is used at the same time, there may be phase problems caused by cross frequency interference or different delay time due to the existence of frequency division system and installation location, so phase adjustment is required. The pink noise generator is connected to the input channel of the mixer, and the level is adjusted to the normal position. The phase meter test microphone is placed in the middle of the field, which is in an equilateral triangle with the speaker. Push up the output push of the mixer, and check whether there is any Valley on the screen of the spectrometer near the frequency division of the full frequency and ultra-low frequency speakers.
If yes, upgrade the corresponding frequency band of equalizer, if not, there is a phase problem. The phase problem will directly affect the sound quality, and it can be solved by equalizer. To solve the phase problem, it is necessary to adjust the phase angle of the frequency divider or the delay time between speakers. When adjusting, pay attention to the display of the spectrometer. First, adjust the phase angle of the low-frequency divider to see if there is improvement. If there is improvement, determine an optimal value and then adjust the delay time. The delay time adjustment depends on the site situation. If the low-frequency speaker is close to the seat, it is necessary to adjust the bass delay. Also, look at the screen of the spectrometer and adjust the delay time to make the curve Try to be a little flat. Minimize phase interference.
After the above adjustment, the next step is to adjust the frequency response curve of the system. Put the test microphone of the spectrometer in a certain position in the seat area, play the pink noise source, watch the display of the spectrometer, and correct the defective place with the equalizer. Put the test microphone in different places, change several more positions, adjust the balance repeatedly to make the frequency response curve of each area as straight as possible.
Next, debug the dynamic control equipment. If the pressure limiter is connected in chain in the system, it is generally used as a protection system, so it mainly uses the limiting function of the pressure limiter. According to personal requirements, only one of the setting methods of the pressure limiter is described here. The pressure limiter can be set to bypass, the input and output gain is set to 0 dB, and the compression ratio is set to "infinite". Then the pink noise signal is sent out from the mixer and gradually pushed up. Observe the input level indicator of the power amplifier, when the clipping indicator light (clip) is on. Connect the pressure limiter, adjust and start
The level knob turns off the clipping indication of power amplifier input. Then increase the output of the mixer by 6 dB or let the output level indicator light reach + 6 dB, and then adjust the starting level a little to make the power amplifier clipping indicator light just start flashing.
After the preliminary debugging of the system level according to the above steps, the debugging of microphone voice can be carried out. Adjust the level of a microphone, without the microphone equalization processing of the mixer, and put the channel push of the mixer at 0 dB (provided that the signal monitored by the stage is taken from the auxiliary output after the push).
The microphone is put on the main position of the stage, and the monitor output control (AUX) is gradually increased, and the output level is gradually raised. When the microphone causes a certain frequency band to howl, the AUX knob is fine-tuning at a certain volume level, and then the corresponding knob on the equalizer is adjusted to eliminate the howling of the frequency band and then continue to raise the level. Adjust to eliminate it, and so on. Wait until the output level push or aux knob of the mixer is adjusted to the normal position (ratio)
