compressors = confusion?

[DLovas]

i'm sure its a very basic concept - but whenever i search it on google i end up on wikipedia with some very confusing results...

so anyway - what (in lamest terms) is a compressor - what does it do? what does it put on the table in terms of production - other than Sidechaining... thats the only thing i know about compressors is the sidechaining aspect.

thanks a lot


Also
I'm just curious - in my line of music - being able to side chain the kick drum or something to a pad is very usefull - yet i find the software (in my case) not too adept at doing this without eating my CPU (time to upgrade? $$$$$$)

either way

not that i plan to buy one - what are some good hardware compressors that can do that?

[visceralvoids]

It's a good topic because everyone has a different way of explaining it. Compressors basically smooth out the dynamics of the sounds/instruments in a mix to make everything sound more even, or with the proper settings, accentuate qualities of instruments. Using them can really tighten up a mix and help make everything the same volume. If you mess with a compressor plug ins presets on a audio of a drum loop you can clearly notice what they can do.
DBX makes some rackmount compressors for $200. Unfortunatley most budget mixers do not have built-in compressors. I'd like to get one of those DBXs to SEND OUT to from my mixer. If you read any studio advice they will always say compressors are a cornerstone piece.

[nathanscribe]

http://www.soundonsound.com/sos/sep09/a ... deeasy.htm

[cryabetes]

I always kind of picture a compressor as an If-then statement for volume levels.

If the incoming signal exceeds -x db [threshold], then divide the volume by y [ratio] after the initial z ms [attack] and reset to typical volume after w ms [release].

The ratio says the amount of gain reduction - ie, 4:1 means it takes 4 db of sound before the compressor to make 1db of sound after the compressor.

As far as sidechaining goes, lots of cheap hardware compressors will have a sidechain input (although they may call it 'key in' or 'detect in').

[cornutt]

A common misconception is that compression increases the volume level of the output. Compression itself doesn't do this -- in fact, it does the opposite. Here's basically what a compressor does: Soft sounds, below a certain volume level, go straight through; the compressor doesn't change them at all. When the input volume rises to a certain point, however, the compressor starts to reduce its gain. So, as the input continues to get louder, the compressor "turns its knob down" and the output doesn't get louder as much as the input. The louder the input gets, the more the compressor has an effect on it. So the compressor is actually making the overall average volume level softer, not louder. However, it's doing it in such a way that loud sounds are effected more than soft sounds.

Most compressors have a "make-up gain" control, which controls an amplifier that comes after the compression section. If you turn up the make-up gain, you can bring the loud sounds back to the level they were at before they were compressed. However, since the soft sounds went through the compressor untouched, the make-up gain effectively makes them louder, and so the average overall level is now louder.

[DLovas]

thanks for the help guys - im starting to understand this a lot better!

[Zamise]

No compressor expert, but the main thing I use compression for is mostly like a quick and dirty equalizer. Problem though comes when it is used too much then it takes a lot of dynamics away from the original sound in favor of something that will just sound louder, distort, and if set just right will keep it barely under a peak clipping threshold. Side chaining, gating and limiting are separate deals, but they seem a regular part of compressing.

[DLovas]

No compressor expert, but the main thing I use compression for is mostly like a quick and dirty equalizer. Problem though comes when it is used too much then it takes a lot of dynamics away from the original sound in favor of something that will just sound louder, distort, and if set just right will keep it barely under a peak clipping threshold. Side chaining, gating and limiting are separate deals, but they seem a regular part of compressing.

And what exactly is gating?

[Zamise]

You know what limiting is? Basically, gating is opposite of that. Its for the quieter noises like line noise or hiss, keeps the gate closed so you don't hear it until it reaches a certain level like if music starts playing then it opens the gate at specified rate. Also good for ducking or making pumping pumping sounds when side-chained.

[blavatsky]

good stuff, but this should be in sound production as it is not about a synth

[DLovas]

good stuff, but this should be in sound production as it is not about a synth

shoot me - my mistake

if a mod wishes to relocate it go ahead

[cryabetes]

You know what limiting is? Basically, gating is opposite of that. Its for the quieter noises like line noise or hiss, keeps the gate closed so you don't hear it until it reaches a certain level like if music starts playing then it opens the gate at specified rate. Also good for ducking or making pumping pumping sounds when side-chained.

whoa I never really pictured gating as a variation of limiting before. Always pictured it as a kind of wall that a sound has to have x db of amplitude to jump.

[tallowwaters]

You know what limiting is? Basically, gating is opposite of that. Its for the quieter noises like line noise or hiss, keeps the gate closed so you don't hear it until it reaches a certain level like if music starts playing then it opens the gate at specified rate. Also good for ducking or making pumping pumping sounds when side-chained.

Gating doesn't necessarily apply to noise though, it's a threshold mechanism for all audio.

A few people here have explained compression quite well, no need to elaborate. If you are wondering what (extreme) sidechaining is exactly, listen to any Com Truise song. You notice how the bass and many other elements of the song are quieter when the bass drum hits? That is a ducking effect (wherein the volume of one instrument is attenuated by another sound) created by the sidechain of the compressor.

As far as using a compressor, the devil is in the attack and release settings. Once you get the hang of adjusting your threshold and ratio, it's pretty easy to hear what is good. It takes a fair bit of trial and error (and track killing) to figure where to put those damned release and attack knobs so that you aren't sucking the life out of everything. Parallel tracking can be a good use here.

(and if you're in the market for compressors, the RNC and RNLA are perfect places to start).

Another good source for this is TapeOp board, where lots of folks actually use compressors instead of just buying them (ala Gearslutz).

[adhmzaiusz]

One good engineering trick to get your compressor popping with the music is to set your threshold to the level you want it to start working at, and set your attack all the way slow and your release all the way fast... play a steady quarter or eighth note snare at the tempo you are working at and gradually bring the attack faster until you hear the effect of the snare snapping, and then gradually bring in the release and set it until the gain is recovering by the next snare hit. Bring in the rest of your song and fine tune the attack and release.

[theotherleadingbrand]

Very interesting thread. I'm learning a lot here. I've always just imagined compression as, "squashing" the dynamics between a minimum and maximum threshold, but have little practical experience actually using it.

One good engineering trick to get your compressor popping with the music is to set your threshold to the level you want it to start working at, and set your attack all the way slow and your release all the way fast... play a steady quarter or eighth note snare at the tempo you are working at and gradually bring the attack faster until you hear the effect of the snare snapping, and then gradually bring in the release and set it until the gain is recovering by the next snare hit. Bring in the rest of your song and fine tune the attack and release.

As far as using a compressor, the devil is in the attack and release settings. Once you get the hang of adjusting your threshold and ratio, it's pretty easy to hear what is good. It takes a fair bit of trial and error (and track killing) to figure where to put those damned release and attack knobs so that you aren't sucking the life out of everything. Parallel tracking can be a good use here.

I'm going to try to use this advice next time I record something. A question though, other than the pumping bassline thing, can sidechaining be good for something like making a voice standout?