Room equalizers typically require precise adjustments with a pink noise generator and a real-time spectrum analyzer. The room equalizer is mainly used to correct and compensate room frequency characteristics. Therefore, the consistency of the hall environment and the actual listening environment should be ensured during commissioning. In addition, room equalizer adjustments sometimes need to be combined with speaker layout adjustments.
The room equalizer compensates for the environmental frequency characteristics by changing the frequency characteristics of the signal. Changes in frequency characteristics inevitably lead to changes in phase characteristics, causing phase distortion. When the amount of room equalization and adjustment is excessively large, especially when a certain amount of adjustment is required to achieve an equalization effect in a band that is not wide enough, although the frequency characteristics of the room are corrected, it is because of phase distortion. Relationships, the sense of hearing will become very poor, this situation will be more prominent for the stereo system. In the case of poor sound conditions, room equalizer adjustments can sometimes be traded off between frequency characteristics and hearing. The flattening result of forcing frequency characteristics can sometimes be self-defeating. The best way is to improve the acoustic properties of the room itself.
1. The debugging process
(1) Use pink noise as a system input test signal. This noise is obtained after the white noise passes through the -6dB/oct filter. Compared with the white noise, the pink noise has a large low frequency energy. Because the pink noise energy distribution is closer to the real music signal, it is often used as a test signal for sound engineering and audio equipment. The speaker's power capacity generally uses pink noise. Generally, the frequency response of mid-range or higher laser players can be set to 20Hz-20KHz+0.5dB, which can meet the test requirements.
(2) The pink noise is input to the mixer and the mixer is adjusted to the standard output level, which is usually OVU, and the output level is +4dB. It should be noted that the EQ on the mixer is adjusted to the flat line, that is, all In the zero position, the frequency of each segment of the test signal is neither increased nor decreased. The room equalizer's frequency adjustment potentiometers are also temporarily set to zero. Slowly increase the amplifier volume leveler can hear the pink signal sound, monitor with a sound pressure meter until the noise level of the pink noise signal in the hall reaches 85dB.
(3) Place the measurement microphone in the center of the hall. Select the switch on the spectrum analyzer to place it in the “OCT” file (this file is the octave filter file, which corresponds to the characteristics of the pink noise). At this time, the LED display on the real-time analyzer is the frequency characteristic curve of the listening environment. The flatter it is, the better the frequency characteristics of the room construction sound.
(4) Adjust the frequency boost/attenuator on the equalizer so that the frequency characteristic curve on the spectrum analyzer appears as a straight line.
After the above debugging is completed, the equalization curve on the equalizer is generally "smoothed". This is mainly to prevent excessive phase distortion when the equalizer is adjusted to the jagged frequency characteristic.
2. Room equalizer adjustment key points
(1) In the low frequency range of about 20-50Hz and the high frequency range of 14KHz or more, the frequency characteristics do not have to be demanded, especially for the low frequency band. Because the general speaker is difficult to extend to 20Hz, reaching 40Hz is considered good. Forcing the low-frequency characteristics of the flat and increase the ultra-low frequency, the speaker will be "out of control" due to the excessively extended low frequency, and the distortion is exacerbated.
(2) The adjustment of the room equalizer should always consider the contradiction between the flat frequency characteristic and the minimization of phase distortion, and make a compromise.
(3) In the case of obvious "peaks" and "valleys" in the frequency characteristics of the built-in acoustic environment, consideration should be given to changing the position of the speakers and trying to change the acoustic characteristics.
(4) The adjustment of the room equalizer is a very meticulous task, which requires repeated adjustments before final adjustment can be made. This is because in the adjustment process, it is often necessary to make some adjustments to the setting of the sound box and the sound environment, and the equalizers will have mutual restraint during the adjustment.
Objectively speaking, the role of the room equalizer is limited, and the defects of the built-in acoustic environment cannot be expected to completely rely on the room equalizer. The smaller the balance is, the better the sound quality. In the absence of a pink noise generator and a real-time spectrum analyzer, the frequency signals of the same amplitude can be sent to the system using the audio signal generator at each frequency point of the selected room equalizer and tested with a sound pressure meter. The sound pressure in the room is adjusted by the room equalizer so that the input signal at each frequency point produces the same sound pressure level in the field. The practical effect of this debugging method is worse than using standard pink noise. Therefore, professional units should configure the pink noise generator and real-time spectrum analyzer as much as possible.
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