【 Weak current College 】 (go) expert detailed professional audio troubleshooting MI-3---Power By 【 China power house network 】

(Ii), Equalizer: Equalizer is the peripheral equipment with the greatest number of devices, so we also need to pay special attention to the following that adjust Equalizer is need to pay attention to some problems and troubleshooting: 1, there are some sound mixer will have 7-9 equalizer, the equalizer only simple adjustment of timbre, belongs to a secondary character, so we use it is best not to such an equalizer for big upgrade, otherwise the mixer main output level tend to be exceeded. Then an equalizer in general have a switch, use this switch when you want to pay attention. 2, some dual channel 15 Equalizer will have a State transfer switch, you can handle double-channel 15 Equalizer converted to single channel 30 equalizer, you will have to pay attention to see every section and then adjust the frequency. 3, we currently use the most is the dual channel 31 equalizer, note the following points: a, 6dB and 12dB switch: there are some Equalizer 6dB and 12dB working state transfer switch, normally or adjust better at 12dB. B high-pass, low pass, or: some equalizer has low pass and high pass adjustment function, adjustment, note that if you put too much bass attenuation of the sound is not too thin a full; the treble attenuation of too much sound too gloomy not penetrating power. C, frequency sliding key: adjust when the equalizer for each frequency sliding key to see if normal; at the same time note sliding keys don't do too much decay or upgrade, especially when upgrading will not exceed 6 dB. D, connection: Equalizer input and output are XLR card Lennon and TRS two ports, in addition to the shape is not the same, the function is the same, but in fact are balanced line port, so we connect the equalizer to use when you "signal cable XLR card and TRS6.35 stereo signal cable to do the balance connection. Equalizer fault example: 1, have the time to help a friend's dance tune, discovery singers singing on stage left without transfusion, to the right when you occasionally have to sing into phenomenon, I first looked at the mixer left and right channels of the output signal is balanced, and then look at the amplifier's volume for the two channels is balanced, then check the peripheral equipment of various input output volume is good, finally found the equalizer right channel for adjustment to 6dB, adjust the left channel in normal 12dB, transfusion of the points in this Equalizer 800Hz, left and right channels to 800Hz frequency attenuation 8 dB, left channel at 12dB State attenuation 8 dB course is normal, no problem; but the right channel of the State of seemingly 6dB attenuation 8 dB actually to divide by 2, then becomes a 4 dB, Equalizer right channel corresponds to the right of the stage, so the primary speaker stage right speaker 800Hz Department transfusion is not strange, at which point the right channel for adjustment back to 12dB fault is ruled out. 2. once in the friends there watching him get an outdoor show, their old equipment in particular, the use of the equalizer has several sliding keys are lost, when I always feel that there is one side speaker sound urn URN, carefully watch the equalizer left channel 630Hz of sliding key off, leaving it a bit, but this was still a little bit, that means the 630Hz high above the frequency up to 12 dB, the sound is not only the URN urn sound strange that I air immediately let a friend with a small screwdriver to adjust the frequency of sliding key to failure is excluded in the normal position. 3. once helped a unit overhaul of a sound, they say there is no sound from a channel, I looked at the other device basic no problem, this system Equalizer output XLR and TRS card you have received the signal output port, then find the right channel TRS stereo signal cable plug inside the circuit, this also caused the right channels of XLR card Lennon ports may short circuit, because the equalizer internal XLR and TRS port lines are linked. Replace the plug after fault TRS6.35 stereo isruled out.

(Iii), the compression: compression is the main feature is, of course, protection equipment, adjust compression below that takes some of the problems and troubleshooting: 1, noise gates THRESHOL: compressor, noise gate does not mean it can get rid of the noise music, it is only useful in systems with no audio signal is in effect, such as: meeting of the leaders in low voices whisper, such unwanted sounds can be used to block the noise gate; but when the leadership of microphone more loudly, noise gate, of course, will not be able to intercept it, otherwise there is no sound out what can do? truth is: when the system useful audio signal burst noise gate threshold level (THRESHOLD), the threshold level has no effect, the system of noise will inclusion in useful audio signals transmitted together, but at that time was the noise of useful audio signal masks, we don't recognize it. Therefore, the noise gate is no way to eliminate the normal audio signal in any noise, it is not like audio workstation in noise sampler that can moderate the Elimination of some of the normal audio noise. Noise gate if adjusted too high music appears "breathing space" phenomenon, it has a no, off, so to avoid this kind of human failure. 2, the compressor's THRESHOLD: compressor section of the THRESHOLD and noise gate THRESHOLD although in part is a kind of threshold circuit, but both function and work status is not the same, two threshold in normal use, the noise gate THRESHOLD may in 99% of time does not work, because most of the audio level signal will be higher than the threshold; and the compressor THRESHOLD may in 70-90% of the time does not work, the opposite is because most of the audio level signal may be lower than the threshold. 3. compression RATIO: adjustment of the compression ratio is determined from the compression is turned into a "comp" or into the "limiter" and its adjustment to combine compressor section of the THRESHOLD, the compression ratio is too lowto no effect, too high and sometimes damage the sound quality. Basically less than 1: 6Compression ratio is compression, greater than 1: 6 compression ratio can be regarded as a limiting functionality. Of course I personally feel that compression ratio adjustment at about 1: 3 is quite appropriate. 4, stereo chain: compression with a stereo chain key (StereoLink), everyone in the adjustment to be careful not to accidentally press this key, as will the stereo signal into Mono signals. 5. express Bypass: I often find that some audio Division has the express compression is still unknown, can't tell what is express state what is working, therefore this point to note. Compressor failure examples: 1, a time-based maintenance to a set of audio equipment, found a bench press machine is not too normal, compact led light 3, 4, and the other side of the compact led should light up 7, 8, but in front of the compression for all devices are working properly, can only be a compressor for itself. Later discovered that the compression is on the back panel has the side-switch on-20, normally to select + 4dB level worked, and other device-level mismatch, compressor for signal easily severely distorted. We use the time do pay attention to avoid this kind of failure. 2. once my friend to me said he was there to audio equipment problems, when you play songs in concert accompanying music system also everything is normal, but when the singers sing loudly suddenly started, the system overall volume will suddenly have a lot of small, like a breath to, and having a tough time and slowly return to normal, I find that they are using compressor dbx 266 of the United States, said phenomenon is the compression of the threshold (THRESHOLD) the threshold level is too low, the compression is overworked. This time the need to raise the THRESHOLD level, this failure is ruled out. This phenomenon is the dbx 266 compressor for a characteristic, therefore we should note that in the future. 3. once I finda lethargic friends to help a dance tune, said that under the sound has just opened, evening dance 8 only secondary speaker speakers burnt on the whole, I find it very strange, except where the sound engineer a serious operation, accidents will happen this kind of "disaster" of consequences. After careful and comprehensive examination I found audio system compressor for only resizing properly, causing such serious consequences. Originally this audio system only in main speaker before configuring a compressor, there is no auxiliary speaker. I found that one compressor for threshold (THRESHOLD) level adjusted too low, at around and 30dB-compression ratio is also adjusted in 6: 1 cent, so that even a normal audio signal had also been a lot of compression, we all know the standard signal level is 0dB, you can imagine, such adjustment, whether the compression is mentioned in the input signal, compression for normal output signal in any case or is not up to standard 0dB level, its consequences are: that night sound engineer always said no sound from the main speaker, ran in a mixer to increase the volume, so that the signal serious distortion, on-site or just hear the voice of the auxiliary speaker, as the main speaker to compressor for thorough "killed", of course, the sound will be very small. This poor little 8 auxiliary speaker speakers to burn it into pieces, and 16 main speaker only significantly but unknown lay to rest. Lessons are painful, but it also from the side shows the importance of the press, we first highlighted THRESHOLD-threshold level and compression ratio, the RATIO is the hope that we can thoroughly understand these principles and features of the knob, adjust the improperly, it can produce catastrophic failure. 4. we all know that some of the mixer will have a mono output of the total volume, there are times I had a project, from the mixer mono output signal to a compressor, the compressor in stereo chain key (StereoLink) open, and then the signal output to a secondary speaker amplifier, a few days there stereo masters say half the auxiliary speaker no sound, I checked and found to press the stereo chain key (StereoLink) does not open, it becomes to press for the left channel signal, right channel no signal because there is no "chain". Through the introduction and examples we should know that the compressor is a very important essential equipment, this need we pay close attention, in particular the project developers, sometimes with single time could spend more money with one compressor, final result is often a stingy, may damage outweigh many shouldn't have damaged device!



(4), e-modulus prescaler: electronic dividers, the main function of course is to give different speaker assigned different operating frequency, and of course protect speaker function, the following saying of adjustment required electronic dividers to pay attention to some problems and troubleshooting: 1, crossover point: in a 2-frequency of the sound system, normally crossover point in the vicinity of more appropriate 130Hz, but in many cases, adjustments to the crossover point is not actually depends on bass speaker, but settled on the treble or full-frequency sound. Because bass speakers work in 300Hz following can, but some in the treble, and full-frequency sound speaker diameter is too small, the dynamic range is not large enough, you must work in order to ensure the above 200Hz their safety, if in this crossover points in the vicinity, then these 130Hz treble speakers work looks very dangerous, so in effect and safety among them or to find a balance. I think dual 15-inch wide-band master sound box it is best not to go through electronic dividers; single 15-inch flexible main speakers; and single 12 inch below the main speakers the best e-mail divider, at least in the above job security 180Hz. 2. volume control: whatever is enter level or adjust the output level, when you want to have a degree, don't drive too big. If you are an individual dividers on volume knob are open to a large, systems of sound pressure is not enough, it will adjust the electronic divider in front of the device's signal level or adjust the electronic dividers following amplifier's level and the volume switch. 3 × 10 button: there are a number of e-modulus prescaler has one: × 10 buttons, we take care not to press it lightly. For example our crossoverPoint adjustment in 200Hz, press this button to 200 × 10 becomes 2000Hz, so unless it is required, otherwise generally do not press this button. 4, bass mode: some electronic dividers back panel has a bass mode choice, it can take 2-channel stereo signal mixed into 1 channel Mono signal, which can reduce the bass sound interference between the speakers. You can use the following as appropriate. Of course if the bass frequency points higher, then the bass speaker sounds will have a certain direction, at this point or 2-channel stereo signal of State work better. 5. stereo mode and mono mode: currently we are using most electronic dividers are mostly of 2 frequency, taking into account the flexibility and versatility, these electronic dividers of the back panel of the General Council has a stereo and mono mode switch, if you put the switch on the Mono working mode, then at this point the electronic dividers from a dual-channel electronic 2 frequency divider becomes a single-channel 3-n e divider. So unless necessary not to easily convert this work switch, otherwise e divider output signal behind the output frequency of the signal would be quite different! minor worsened the sound, to also be damaged equipment! 6, System bass signal output and treble signal output must not be confused, or treble signal to the subwoofer speakers, bass signal to a high-pitched sound, so diametrically opposed approaches sound system is really no sound comes out, because the frequency wrong! maybe also burned speaker! e divider failure examples: 1.05 friends in Changsha had a large bar, audio systems use a single CCP 12-inch wide-band 16 main speakers, dual 18 inch subwoofer speaker 22 only, there are other 20 only secondary speakers. However, opening a few days later found the main speakers in single 12-inch speaker out 2 only, start where technical staff thought it was normal damage, replace the 2 new speakers, but then a week in the Inland one and bad 6 only 12-inch full-frequency Horn, this is not normal, and in addition to the 12-inch main speaker fails, other speakers are no problem. Then I went to help checked system, found in the e-modulus prescaler Division of frequency is too low, I put the divider crossover point from 130Hz upwards to 230Hz, this problem will be solved, but the bass effect is better. In fact, the reason is simple: this system due to balance human performance, use a human voice performance better 12-inch wide-band at the beginning of the main speaker, electronic frequency divider crossover point in 130Hz concept, what is this? means system 22 44 only bass speaker only 18 inch horn can only issue 130Hz following sound effects really limited, a big waste of resources; and sub-woofer system 16 only 12-inch speaker has to pay more than sound 130Hz, we know that the sound intensity and excitement of the 200Hz around, so this 16 only 12 inch horn as diameter small simply overwhelmed, the frequency and method of use can result. Adjusted, 16 only main speaker only 230Hz above voice, the voice of 230Hz following only by 22 so sub-woofer is responsible for two sets of speaker base, collocation and more perfect, the key is to play their respective specialties. I have said above, the effect is important, but security is more important. 2, Shantou area a slow roll bar, use the 8 only double 18 inch bass speakers, 10-15-inch wide-band master speaker, party a shall always feel the bass is not enough, you do not want to increase the bass. I check system and found 10 main speaker through electronic divider, due to insufficient party said bass, acoustic bass frequencies allotted in the very high, at about, imagine 350Hz: adjust though it has increased by only 8 sub-woofer and loudness, but 10-15-inch wide-band main speakers at the above work, the 350H main speaker can say basically didn't give any bass. I immediately put the 10 main speaker line changed it to use the equalizer output directly, not through electronic dividers, the effect will be quite different! what I think we can calculate: let 10-15 inch main speaker of 20 only 15-inch speakers, increase the number of bass energy! some friends say that full-frequency sound without electronic dividers like does not conform to the rules? but we can not be rigid, to pay attention to the fact that breaking it!