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Compressor question. Bring the noise!
Old 9th May 2006
  #1
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Compressor question. Bring the noise!

Most compressor theory talks about how compressors bring up the noise floor. I dont get that. Is this a perceived effect or real. Please dont answer "perception is reality." What I dont get is that if the compressor is only supposed to kick in at the threshold and not mess with what's below, then how does that make sense. I got an answer once that a softknee anticipates the threshold a little bit, but what if its a hard knee? I could see if the threshold was around the level of noise how this would make sense, but outside of the softknee explanation I dont get this comment about bringing up the noise floor.

thanks
Old 9th May 2006
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A compressor doesn't bring up the noise floor - you're thinking of compressors that have an auto-gain function, whereby they increase the overall gain to compensate for the gainreduction of the comp'.........i always found that a silly and slightly dishonest concept! (in a compressor i mean.....in a limiter it makes sense)

What's also possible is that you'll put something louder because you've brought the loud parts down a bit (with compression)......if this happens, then you've effectively raised the noise floor.......i wouldn't worry about it though.

Last edited by Darius van H; 9th May 2006 at 09:13 PM..
Old 9th May 2006
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Compression by itself will reduce volume, hence the term "gain reduction". When the loudest parts of your recording have been made quieter, you now have a quieter signal, with more headroom at the top of your signal, allowing you to boost the entire signal, noise and all.

What compression is doing is lowering dynamic range, bringing noise (quietest signals) up, and loud peaks (loudest signals) down.

So while compression itself is not changing the volume of the noise, the gain required to compensate for the compression WILL bring the noise floor up. Make sense?
Old 9th May 2006
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Quote:
Originally Posted by DeeDrive
What compression is doing is lowering dynamic range, bringing noise (quietest signals) up, and loud peaks (loudest signals) down.
Watch out......careless words will confuse the confused.......compression doesn't bring up the noise.
Old 9th May 2006
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Quote:
Originally Posted by Darius van H
Watch out......careless words will confuse the confused.......compression doesn't bring up the noise.
Right, but does anyone ever (within reason) use a compressor without makeup gain?

Certainly not for creative purposes, but only for sheer level control maybe... but then what choice do you have...

Chances are, if you're using a compressor, you're going to be bringing up the noise floor.
Old 9th May 2006
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Quote:
Originally Posted by nathanvacha
Right, but does anyone ever (within reason) use a compressor without makeup gain?

Certainly not for creative purposes, but only for sheer level control maybe... but then what choice do you have...

Chances are, if you're using a compressor, you're going to be bringing up the noise floor.
Make up gain or not, the noise floor will rise RELATIVE to the average and peak level of the track. The noise floor is in there with the "lowest" part of the signal.
Old 10th May 2006
  #7
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Every electronic circuit brings it's own noise to the party. So if you add a compressor to the loop - maybe via D/A and A/D - you could be adding a layer of noise before you even begin.

Certainly the 'compression' part of a compressor doesn't raise the noise floor - it would actually duck the incoming noise.

But most compressors offer make up gain, and most people apply make up gain after compression. That's what raises the noise floor, as well as the noise produced by the compressor itself.
Old 10th May 2006
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No offense, but is this really an issue? Raising the noise floor is the last thing I worry about when I compress.
Old 10th May 2006
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Quote:
Originally Posted by robot gigante
No offense, but is this really an issue? Raising the noise floor is the last thing I worry about when I compress.
Gigante,

I dont know what you mean by an issue. I was just trying to understand some of the theory. I didnt understand why much of the text says that the noise is raised, when noise is below the threshold and everything under the threshold was supposed to be unaffected. From what I can tell it is raising the make up gain that does this, which makes sense, however none of the text I have read has said that. Although in practice I have also most of the time used the make up gain I dont always.

Masterer says that it is a question of relativity and that is what I originally I had thought. But it seems like a subtle detail and I think I get a better feel for this now.

thanks for the great responses!

Last edited by crabtwins; 10th May 2006 at 11:23 AM..
Old 10th May 2006
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Quote:
Originally Posted by crabtwins

Masterer says that it is a question of relativity and that is what I originally I had thought. But it seems like a subtle detail and I think I get a better feel for this now.

thanks for the great responses!
It's "subtle" if you barely compress a quiet mix. If you compress the crap out of a drum room, you get a not so subtle increase in noise floor.

In the big picture, it's almost always a non issue... add noise, add distortion, whatever it takes.
Old 10th May 2006
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Quote:
Originally Posted by nathanvacha
Right, but does anyone ever (within reason) use a compressor without makeup gain?

Certainly not for creative purposes, but only for sheer level control maybe... but then what choice do you have...

Chances are, if you're using a compressor, you're going to be bringing up the noise floor.
Isn't smoothing dynamics and controlling volume creative?.....sometimes i get the feeling that most people think compression is for making something louder - that's not how i think of it at all.
Old 10th May 2006
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Quote:
Originally Posted by robot gigante
No offense, but is this really an issue? Raising the noise floor is the last thing I worry about when I compress.
I record a lot of stuff "on location" and it's always an issue to put a compressor in at the tracking stage. You get all kinds of fun stuff like a/c, trains, traffic, aircraft, depending on the recording chain, HPF, etc. Even in a quiet space, you can pull in the click track from the headphones. I guess some people don't track with as much compression as I sometimes do.


Quote:
Originally Posted by Darius van H
Isn't smoothing dynamics and controlling volume creative?.....sometimes i get the feeling that most people think compression is for making something louder - that's not how i think of it at all.
I always think that using a compressor is for a specific sound, or effect, so I agree with you.

If it's for control of levels, ride the fader.
Old 10th May 2006
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Quote:
Originally Posted by Darius van H
Isn't smoothing dynamics and controlling volume creative?.....sometimes i get the feeling that most people think compression is for making something louder - that's not how i think of it at all.
Quote:
Originally Posted by max cooper
I always think that using a compressor is for a specific sound, or effect, so I agree with you.
If it's for control of levels, ride the fader.Oh no, I completely agree. I was trying to give a scenario to follow my "does anyone ever..." question. What you said is exactly the point I was making... You're compressing because you want the character/sound... if you're getting too much noise to make it unuseable, you need another unit or there's something wrong with the track in the first place.

--Although, It wouldn't be the first time someone used a compressor just to tackle overs...

Last edited by nathanvacha; 10th May 2006 at 07:01 PM..
Old 10th May 2006
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technically, it dosent raise the noise floor....

untill you turn up the make-up gain. Which you will.
Old 11th May 2006
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Quote:
Originally Posted by max cooper
I record a lot of stuff "on location" and it's always an issue to put a compressor in at the tracking stage. You get all kinds of fun stuff like a/c, trains, traffic, aircraft, depending on the recording chain, HPF, etc. Even in a quiet space, you can pull in the click track from the headphones. I guess some people don't track with as much compression as I sometimes do.
OK, sure. I thought we were talking about compressing during the mastering process, in which case it really is a non-issue. I can see it being an issue in yours and other situations however!
Old 11th May 2006
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Compression is gain reduction, nothing else. Gain reduction doesn't add noise to the noise floor. So in itself it doesn't add noise. But since you add noise from the unit itself by applying it on the signal (for instance calculation errors ITB) it adds a small amount of noise as well, in that way.

These days the noise floor is normally rather low, but since the final mix is full of additional noise there is less headroom left for that noise to exist before it creates artifacts (= gets loud enough), for instance during limiting, when the increased amplitude on each noise frequency can sum up to audible distortion. When thinking about how popular extreme limiting has become, a low noise floor will have an important impact on the "available" headroom and therefore on the maximum loudness/clearity ratio of the mix. There is plenty of noise added to the signal, no need to make it worse by having a high default noise floor level.
Old 25th June 2011
  #17
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it just makes the attack more pronounced by keeping it at level 5 for 30ms then bringing it down to level 4.4 after, creating a sudden POP!!! at the beginning of each attack, making it punchy-er

at least thats how I use it, great for everything really

I think gain is just more for the sound of the unit or plugin, but not the most important part of compression in my opinion
Old 26th June 2011
  #18
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Quote:
Originally Posted by nathanvacha View Post
Right, but does anyone ever (within reason) use a compressor without makeup gain?
Very often in mixing.... am I missing something here? I'll often have a vocal, for example, sitting perfectly in a mix, and then you notice a few loud phrases.. stick a compressor on, gain reduction on those phrases, no make up.

That is compression in the macro dynamic sense, and is just as relevant to modern mixing than using compression in a micro dynamic sense to change the "sound" of the voice.
Old 26th June 2011
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Yep in mixing very regularly.

I've used compressors in mastering without makeup gain as well.

Especially - compressor with sidechain (for instance, with the sidechain focussed on an edgy snare in a dense mix.)

Also - compressor used without the peaks hitting the threshold at all (just for the sound of the unit.)
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