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

(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 low to no effect, too high and sometimes damage the sound quality. Basically less than 1: 6 ratio of compression, the compression feature is 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 find a 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 soundI 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!