Compressors!!

[A. R. Mac]

I have a very basic understanding that compressors make things louder. Things like threshold, knee, ratio, and sidechains(especially sidechains!) all escape my comprehension. Except for the sidechain, I use them all with some success but still very little understanding of what they actually do. Just looking for insight or a point in the right direction. Thanks in advance.

Mac

[IMF OnSite Recording]

Compressors actually reduce volume, hence the term "gain reduction". By reducing certain aspects of a signal you are, in turn, leveling louder parts with the quieter parts. When you bring the gain back up, which is referred to as "makeup gain" (the compensation for the gain LOST in the process of compression), if done right, it would have a thicker, possibly louder apparent volume. Before I go off on a tangent and start making absolutely no sense, I will post this link to a thread that was right on the same page you posted this thread. The compression horse has been beaten to death on this site, so here it is:

Compression Basics

[A. R. Mac]

Thanks IMF. I actually stopped being lazy and went and did a little research myself. I came across a document similar to the link you sent me. I have a couple of more questions. I'm a little fuzzy on the knee and ratio settings but I'm sure with more reading and playing around I'll be able to sort those out so this is not so important. My main concern now are these settings I see. RMS Opto and Peak. What do these do?

[Jeronimo Mora]

Compressors technically can make things louder if you want. Think "Transient Designer". If you set the attack to a few ms to let the initial transient through, the release to a couple hundred ms to catch the tail, you can turn up the make up gain and that would then boost the overall volume of the tail.

[brandondrury]

This is something I've covered in depth in Killer Home Recording. So far everyone is right.

It's one thing understanding what a compressor does. It's another thing using that information to make the noise you want.

My advice is to put a brickwall limiter on the 2bus (set for subtle). Now turn the threshold and ratio to the most aggressive settings on whatever. (Snare drum, vocal, etc). Start playing with the attack and release. Turn 'em all the way up and all the way down. This is the best way to actually understand how to use compressors from a sonic standpoint. After a while, set them to more subtle settings.

Brandon

[Stan_Halen]

Thanks IMF. I actually stopped being lazy and went and did a little research myself. I came across a document similar to the link you sent me. I have a couple of more questions. I'm a little fuzzy on the knee and ratio settings but I'm sure with more reading and playing around I'll be able to sort those out so this is not so important. My main concern now are these settings I see. RMS Opto and Peak. What do these do?

What compressor are you using? Do a lot of reading, as well as playing with the compressor functions on an audio track, to try to understand this stuff. Some "pro" mixers still struggle with how it works (i.e. Dave Pensado).

Basically, the "knee" setting is like soccer: Bend your knee a lot and kick the ball ... you can kick it far (hard). Bend your knee just a few inches, you can kick the ball a few feet (soft). Start with the softer knee settings if you can, until you get a feel for it. Hard knee will make it "sound compressed" and may work against you. Only use this once you understand the function and desire that sound.

Ratio is like games at the amusement park. The "kiddie" games, with maybe a 3:1 ratio, let you win some small stupid prize after 3 throws at the target. The "big boy" games are more like 8:1 ratio or higher, you only win a prize (though usually a better one) if you play a bunch of times and hit the target. Start with low ratios (3:1) until you understand how it's working. The 8:1 and higher ratios get into "limiting" and are the big-boy "smack it down" settings.

Usually, your choices are "Peak vs. RMS", or "Opto vs. Electro". Again, reading the manual that comes with your compressor (if there is one), or reading up on the subjects, will give you the knowledge to make these choices.