1. Line inspection
According to the system circuit diagram, carefully check the circuit connections and confirm that the circuits are functioning properly.
2. Setting the initial state of the device
Set the amplifier input to the minimum and set the input/output knobs of all peripheral devices to the 0 decibel position or the middle position. Power on in the order from the front stage to the back stage (without turning on the amplifier first), check that all devices are powered on normally, and then power on the amplifier.
3. Preliminary inspection of system status
At this point, turn on the gain control of the amplifier appropriately, play a familiar CD, and adjust the input level of the mixing console to the basic normal position. Slowly push up the mixer knob and listen for the sound produced by the speakers to see if it is normal and distorted. If it is not normal, immediately shut down and check.
4. Speaker and system polarity detection
After the system is basically normal, turn on the power of all devices, set the amplifier level to maximum, pull down the output pusher of the mixing console, connect the phase meter generator to the input channel of the mixing console, turn on the phase meter power to adjust the output gain and the input gain of the mixing console to 0 decibel on the mixing console indicator. Slowly push up the output pusher of the mixing console until the "bang bang" sound from the speakers reaches sufficient volume (if the volume is not enough, the test results may not be accurate), and use a phase detector to check whether each speaker is in phase or consistent with the description in the speaker manual. It is best to turn off other speakers during testing to prevent interference and ensure accurate detection one by one. If there is any abnormality, check if the speaker cable is reversed or if the system connection cable is reversed. You can adjust or replace it before testing again.
5. Phase adjustment
If a combination of ultra-low frequency and full frequency is used simultaneously, there may be phase problems caused by cross frequency interference or different delay times due to the existence and installation location of the frequency division system, so phase adjustment is required.
Connect the pink noise generator to the input channel of the mixing console, adjust the level to the normal position, and place the phase meter test microphone in the middle of the field, forming an equilateral triangle with the speaker. Push up the output pusher of the mixing console and check if there are any valleys on the spectrum analyzer screen in the frequency band near the full frequency and ultra-low frequency speaker frequency division. If there is, increase the corresponding frequency band of the equalizer. If it cannot be increased, there may be a phase issue.
Phase problems can directly affect sound quality, and using an equalizer is nothing more than a solution. 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 spectrum analyzer display. First, adjust the phase angle of the low-frequency divider to see if there is any improvement. If there is improvement, determine the optimal value before adjusting the delay time. The delay time adjustment depends on the on-site situation. If the low-frequency speaker is close to the seat, it is necessary to adjust the delay time for the bass. Similarly, by looking at the spectrum analyzer screen, adjust the delay time to make the curve as flat as possible. Minimize phase interference.
6. Frequency equalization
After completing the above adjustments, the next step is to adjust the frequency response curve of the system. Place the test microphone of the spectrum analyzer in a certain position within the seating area, play the pink noise source, observe the spectrum analyzer display, and use an equalizer to correct any defective areas. Place the test microphone in different locations, change several positions, and repeatedly adjust the balance to make the frequency response curves in each area as straight as possible.
7. Debugging dynamic control equipment
The general dynamic adjustment equipment is a pressure limiter. If the pressure limiter is connected in a chain in series in the system, it is usually used as a protection system, so the main function is to use the limiting function of the pressure limiter. According to personal needs, only one method of setting the voltage limiter is described here. The voltage limiter can be set to BYPASS, the input/output gain can be set to 0 decibels, the compression ratio can be set to "infinity", and then a pink noise signal is sent out from the mixing console, gradually increasing. Observe the input level indicator light of the power amplifier, and when the clipping indicator light (CLIP) lights up. Connect the voltage limiter and adjust the start level knob to turn off the power amplifier input clipping indicator. Then increase the output of the mixing console by 6 decibels or make the output level indicator light reach+6 decibels, and then adjust the startup level slightly to make the amplifier clipping indicator light just start flashing. So far, the level debugging of the system has been completed, and the sound tone adjustment and effect processing (including effectors, exciters, etc.) need to be fully handled by the sound engineer. Of course, in audio engineering, this is usually operated by technicians from audio companies.
