First, the phenomenon and system situation
1. Due to external interference, the sound reinforcement system can hear the broadcast sound.
2. There is no sound in the system subwoofer.
3. The function of monitoring the signals of the mixer before the fader can not be realized.
4, the effect can not add effects.
5, the system background noise is relatively large
Other checks, there are problems with system configuration and installation:
1. The level of system equipment is unbalanced. For example, mixers, amplifiers, speakers, etc. are high-end imported products, while equalizers and compressors are domestically produced brands (lower grades).
2. The equalizer is equipped with 3 sets. The main output is equalized separately, the subwoofer output is equalized, and the auxiliary output is equalized.
3. The amplifier installation is not standardized. Due to the heavy weight of the power amplifier, the front panel of the power amplifier is distorted due to the absence of the mounting bracket.
4, the speaker placement is not adjusted according to the venue and the use of the situation, resulting in microphone sound reinforcement is easy to produce howling.
Second, the cause analysis
1. You can hear the sound of the radio station.
The reason for this situation is that the signal line connected to the MIC input end of the mixer is poorly shielded, and the broadcast signal is serially connected to the sound reinforcement system, and the sound is detected and amplified, so that the sound of the broadcast is heard. Although the broadcast signal is very weak and it is a radio frequency modulated signal, it is impossible for a general sound reinforcement system to hear the broadcast signal. However, since the mixer is at the microphone input port, the input sensitivity is high, such as poor input signal line shielding (shield layer). If it is not grounded, it will function as an antenna, and a series of circuits of the system equipment will play the role of detection. It is not surprising to hear the radio broadcast.
2. The system has no subwoofer output.
From the flow of the signal of the system, the general subwoofer signal is obtained by dividing the subwoofer signal from the main channel signal or the group channel signal by the electronic frequency divider, and then amplified by the corresponding power amplifier and sent to the ultra low sound box. From these points of view, the point is to check whether the connection cables, connectors, and related equipment are normal.
3. The function of monitoring the signals of the mixer before the fader can not be realized.
The above phenomenon is mainly caused by the unfamiliar signal flow of the mixer, and the button and the output knob of the corresponding button or the monitor output portion are not placed in the correct position.
4. The system has a large noise interference.
For such so-called noise, we must pay attention to the identification, whether it is audible or electrical noise (sand of water) interference. For the former type of noise, the possible cause is that the quality of the audio signal cable is inferior, the shielding layer is broken, the connector is not soldered, and the connection is not strictly connected according to the balance transmission requirements. It may also be that the system is poorly grounded or not grounded; A type of noise is generally caused by equipment. Due to the poor performance of the mixer, power amplifier and peripheral equipment, and the low index, the signal-to-noise ratio is often low, which is accompanied by a large electrical noise output.
5, the system can not add effects
As we all know, there are many ways to access the effect system, but the most commonly used is the so-called parallel method. This connection is to input the effect through the AUX output of the mixer, and the output of the effect is returned to the LINE of the mixer. This connection should work normally. After a certain auxiliary output to the effector, ensure that the corresponding AUX channel knob of a certain input is turned on, and the corresponding AUX output knob is also turned on, so that the effect can be adjusted. The signal of a certain channel of the sound station ensures that the knob and effect mode of the effector itself are correct, and finally the effect input channel of the returned effect is correctly regulated. All three links must be correct and the system can be added.
6, system equipment configuration is not balanced
When we configure a system's devices, we must first consider the device selection. A basic principle is that the grades of the various devices in the system are basically the same, and there is no device with high and low disparity in the same system. Otherwise, because of the theory of wooden barrels, high-end equipment can not exert excellent performance and become the ear of the scorpion. In the multi-function hall system of the hotel, high-end mixers, amplifiers, and speakers are equipped with low-end peripheral equipment, and the system performance is greatly reduced. It is no wonder that the effect is not good.
7, how to use the equalizer
The equalizer is the abbreviation of the room equalizer. As the name suggests, it is used to balance the frequency transmission characteristics of the hall. Such a device must perform gain adjustment on 31 frequency points one by one through an audio spectrum analyzer to obtain a frequency characteristic curve conforming to the corresponding technical standard. It is impossible to try to adjust the equalizer by hand and obtain the frequency characteristic curve that meets the corresponding technical standards, unless you are an expert who has rich experience in listening and practical experience. For this function room, after the above analysis, in fact, everyone has already understood that adding an equalizer in the subwoofer channel and the auxiliary channel has no meaning to change the frequency transmission characteristics of the entire hall. Only the main channel and the return channel (if any) can improve the frequency transmission characteristics of the hall and improve the sound quality.
8, the installation of the power in the cabinet
Unless it is a large-scale, professional sound reinforcement system, it is generally equipped with a dedicated power amplifier room. With a dedicated power amplifier cabinet, the power amplifier is always installed in the same cabinet as other system equipment. The requirement for installation is that the amplifier must be placed on the shelf of the cabinet and then secured with panel screws. Installations like the hotel's multi-purpose hall amplifiers are not standardized.
9, the speaker position
The placement of the speakers is very flexible and is the main part of testing personal experience and flexibility. The halls are in an ever-changing form, with different functions and inconsistent use requirements. There is no uniform location for installation. This has caused confusion for quite a few audio practitioners, and most of us often feel at a loss. Indeed, the placement of the speaker is too important, it not only affects the uniformity of sound pressure distribution in the hall, but also affects the use of the system. To say that it is popular, is that it can guarantee that the sound level and clarity of each place in the hall will be the same, and at the same time, the volume of the microphone will not be opened. Those with multiple speakers placed in the microphone and the microphone facing the speaker must be prohibited.
Third, the processing method
With the above analysis, we should understand the reasons for the problems in the multi-function hall audio system and the measures that should be taken.
First, we replace the connection cable of the entire system and re-weld the connector according to the balanced connection.
Second, replace the peripheral equipment, replace the original peripheral equipment with the DBX260 audio integrated processor, replace the original effect with the Danish TCM-ONE effect, and adjust the settings correctly.
Third, increase the shelf, reinstall and fix the amplifier.
Fourth, increase the shielding ground wire so that the equipment is well grounded.
Fifth, adjust the position of the speaker, according to the geometric sound line method, so that the speaker has a good radiation angle (direct sound coverage in all positions), while avoiding the use of the microphone will not face the speaker.
Sixth, remove the extra equalizer.
Seventh, check the quality of the ultra-low speakers and the connectors, re-adjust the subwoofer channel, use the DBX260's two bass channel output, feed the amplifier to promote the ultra-low speaker.
Eighth, use the mixer group 1, 2, increase the return channel, configure the DBX2231 equalizer for equalization.
Ninth, the use of mixers 3, 4, add auxiliary channels, flexible control of the use of auxiliary speakers.
Finally, use the automatic equalization function of the DBX260 to adjust the frequency characteristics of the hall and the auxiliary channel delay and feedback suppression, and configure the corresponding effect mode.
After taking the above measures, all the problems that existed before were completely eliminated, and the effect was obviously improved. The hotel side was very satisfied.
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