A compressor or limiter is an automatic volume control. Learn about the functions and controls of compressors/limiters, plus get tips on setting up PA sound systems, in this free professional music video from an expert PA system designer.
Hi! My name is Kip Bradford and I am here on behalf of Expert Village. The next thing we want to do is take a closer look at our compressor limiter. Now this is our compressor limiter and as we mentioned earlier, it has a button that will allow us to combine both channels to link them so that they both work exactly the same. The functions that we have in a compressor limiter are as follows. We have a control called the threshold and what that means is that what point in our dynamic range in the level of volumes above and below are going up and down. At what point do we want our compressors to begin to do its job. Then we have attack and attack tells us once the signal goes above the threshold how quickly in milliseconds do you want the compressor to engage. Then we have release in seconds from half a second to 3 seconds on this particular unit and this tells us once the compress signal falls below our predetermined threshold, how quickly we want our compressor to release the signal or to quick compressing the signal. Then we have ratio which tells us how much compression we are going to use. So a 1 to 1 ratio means that nothing is going to happen because once the signal hits the threshold or goes above the threshold for every decibel that goes above the threshold, it will return at the output of the compressor 1 decibel. So 1 decibel above will give us 1 decibel, 2 decibels above will give us 2 decibels. If we go to a 2 to 1 ratio, that means for every 2 decibels above the threshold, will get back 1 decibel. So if it is 2 decibels over, we will get 1 decibel at the output. So what is a good general setting for overall compression in your space. I find that by setting my compression ratio to about 2 to 1 and my attack time to about 5 seconds, my release time to about 1 second and then I will move this threshold until I see that I have getting a little reduction, just a few decibels off of the top of my program material and then if I need to I will bring the output up just a little bit if I reduced the program material by too much. Years ago before they had compressors, they would actually manually control compression and compression is essentially automatic volume control.