Originally Posted by ScumBum
Thanks for the info....
Now if limiters are are meant to catch and stop the transient , and never accentuate the transient like a compressor can , why is there a need to adjust the attack ? Shouldn't it just be set to the fastest setting there is so no transients get through ?
Good point. A lot of people just do that and get away with it. Some compressors don't even have the attack parameter (dbx 903s aka 160, Neve 2254s etc). There's a serious danger of sucking the punch out of the mix though. Most pros use compressors to CREATE transients and limiters to control them. That way you have all the punch you want while maintaining total control over it. Listen to a few Chris Lord-Alge mixes - this guy is like God in creation.
In general the terminology referring to dynamic control is the most confusing thing in pro audio theory IMO. Some say the difference between compressors and limiters is in ratio, some say in how often the unit performs gain reduction in your programme. It took me years to figure out what the hell people were talking about. For me the easiest way to look at it is:
COMPRESSORS have to do with RMS. They control your programme envelope, without touching the transients. Now how often you want this unit to engage throughout your mix totally depends on you programme and your taste. Most people have the units on low ratios working constantly in order to maintain constant control over the sustain part of the sound. Another term for this type of device is a Leveling Amplifier which to me really summs it up. A lot of classic units don't even have a ratio control but rather a 'soft knee' or 'OverEasy' response to input signal as in the more you put in not only the more GR you get, but also the higher the compression ratio becomes. But still it's all RMS.
LIMITERS perform transient compression. In order to catch transients you are likely to need a fast attack (but totally dependant on the nature of programme as in a handclap has a very fast transient whereas vocal transients are much slower for the most part). How high the ratio is is still up to you. If 3:1 is all that's needed to keep your transients in check - go with god. In most cases it isn't though, hence the stereotype of limiters having high ratios. Bottom line - limiters are for controlling transients.
More often then not you end up with both a compressor and a limiter on a given instrument troughout the recording/mixing process. But there are no rules as to how high the ratios should be or how hard the device should be working - when you reach for the tool though you should know what you wanna use it for - sustain or transients.