Can someone explain to me the function of a compressor?

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CapnLockheed
KVRAF
2281 posts since 12 Mar, 2002 from Central NY

Post Wed Oct 16, 2019 5:53 pm

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cfanyc
KVRist
312 posts since 8 Dec, 2013

Re: Can someone explain to me the function of a compressor?

Post Wed Oct 16, 2019 8:55 pm

thru the magic of copy-paste from a previous thread here in kvr:

So what are the intended high level uses of compressors? Off the top of my head:

1. Peak taming, ie controlling signals that are too dynamic so that they do not break an eardrum or loudspeaker or do not distort unwillingly
2. Leveling, i.e., making sure that the signal does not go too low or too high, under the assumption that too low we cannot hear and too loud is unpleasant or even dangerous.
3. Loudening, i.e., raising the overall perceived volume of the material.
Loudening has also the psychoacoustic effect of the signal appearing more detailed.

More specific and nuanced intents falling under the above categories but requiring special consideration:

a. Altering the attack and sustain characteristics of transients. Shorter attack = more punch/”bigger sound”, longer attack=softer sound, longer sustain=more ambience/slower rhythms, shorter sustain=less ambience/faster rhythms.
b. A byproduct or altering the short transients is that the frequency content is changing. Softer attacks=>less high frequency content.
c. Ducking (exaggerated) = as stylistic effect form some EDM genres.
d. Ducking (invisible) = to avoid frequency collisions among instruments occupying same parts of the spectrum.
e. De-essing, de-breathing, eliminate plosives in vocals.
f. Making thin signals sound thicker/denser. E.g., making reverb tails thicker. Or making a mix sound more dense and more energetic.
g. Making a track more audible in a mix without raising its fader (hence not going over the max allowed volume level).
h. Providing cohesion to a set of audio signals (due to the fact that they are compressed together, they appear as if the occupy the same sonic space/time or are related). This the “buss glue” effect.
i. As a substitute to eq-ing that has more movement to it than static eq.
j. Combined with frequency spectrum splitting, to emphasize the lower or higher parts of the spectrum (eg., huge low end or pronounced mids etc.).
k. As a control mechanism for vocal “throws”; or reverb that activates when notes are not played (to fill in compositional gaps); or layered reverbs (front and back) that activate as a function of how loud the signal is.
l. To raise only specific low level signals (upward compression) so that quite details can be heard.
m. To comply with loudness and dynamic range broadcast standards.
n. Also let’s not forget that various compressor designs introduce harmonic or other distortion and this distortion alone or in combination with the compressed signal are sometimes desired.

Now, if you throw in expanders, gates, parallel and sequential combinations with other tools as well as stacking the above, you can get a myriad more effects for specific situations.

Michey
KVRer
17 posts since 24 Sep, 2019

Re: Can someone explain to me the function of a compressor?

Post Wed Oct 16, 2019 10:34 pm

mladi wrote:
Wed Oct 16, 2019 8:27 am
I use this one:

Image
Wow... That is some colourful compressor !
Is it an emulation of the Hyundai Tucson ??
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Mozex
KVRist
283 posts since 18 Mar, 2019

Re: Can someone explain to me the function of a compressor?

Post Wed Oct 16, 2019 10:40 pm

Ah it changes dynamics. I think I have a knob for that in the "mastering" tool. To be honest, I tried a few compressors, did not hear any difference. I will look at the videos you all shared. Thank you.
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Mozex
KVRist
283 posts since 18 Mar, 2019

Re: Can someone explain to me the function of a compressor?

Post Wed Oct 16, 2019 10:46 pm

@Mushy Mushy: looking at the video now it looks its more for vocals use? I do have a question. Sometimes when I play a pad suddenly the pad begins to play louder in a part of the song. I then have to reduce the volume but then it plays to silent in other parts. If I understand what I have seen untill now (I am only 3 minutes in the video) a compressor can fix this? Or am I wrong?
-What is that? Music?
-No its a chicken noodle.

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Mozex
KVRist
283 posts since 18 Mar, 2019

Re: Can someone explain to me the function of a compressor?

Post Wed Oct 16, 2019 10:51 pm

@ cfanyc thank you thats very helpfull. I have a question to everyone: I assume I need to put this on my master bus?
-What is that? Music?
-No its a chicken noodle.

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Mozex
KVRist
283 posts since 18 Mar, 2019

Re: Can someone explain to me the function of a compressor?

Post Wed Oct 16, 2019 10:54 pm

@jochicago I only have these compressors to my availablility (It are a few of the the plugins that are available in the all acces pass): https://www.slatedigital.com/virtual-analog-bundle/
-What is that? Music?
-No its a chicken noodle.

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DJ Warmonger
KVRAF
3463 posts since 7 Jun, 2012 from Warsaw

Re: Can someone explain to me the function of a compressor?

Post Wed Oct 16, 2019 11:02 pm

Compressor is automated volume controller. That's all.
What compressor does, you can do manually with gain automation - but people just don't have time to do that.

Usually it's used to even out volume levels, but can also accentuate transient portion of a signal.
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fmr
KVRAF
9038 posts since 16 Mar, 2003 from Porto - Portugal

Re: Can someone explain to me the function of a compressor?

Post Thu Oct 17, 2019 12:40 am

Mozex wrote:
Wed Oct 16, 2019 10:40 pm
Ah it changes dynamics. I think I have a knob for that in the "mastering" tool. To be honest, I tried a few compressors, did not hear any difference. I will look at the videos you all shared. Thank you.
One thing I think wasn't mentioned yet, and may be the reason why you don't notice the compressors when you used them, is the threshold.

Threshold is the volume limit above what the compressor starts to work. It means that, if you set the compressor to a ratio of, let's say, 4:1. but you don't touch the threshold control, and that one is set to the top (which is usually the default position) the compressor will never work, and you will not notice it.

You need to define above which level compression starts to work (for example -8 dB). Every time the audio material goes above that volume level, the compressor will start to work. Every time the audio drops below that volume, compression will stop.
Fernando (FMR)

Mushy Mushy
KVRAF
13039 posts since 7 Sep, 2008

Re: Can someone explain to me the function of a compressor?

Post Thu Oct 17, 2019 12:44 am

Mozex wrote:
Wed Oct 16, 2019 10:46 pm
@Mushy Mushy: looking at the video now it looks its more for vocals use? I do have a question. Sometimes when I play a pad suddenly the pad begins to play louder in a part of the song. I then have to reduce the volume but then it plays to silent in other parts. If I understand what I have seen untill now (I am only 3 minutes in the video) a compressor can fix this? Or am I wrong?
They’re useful for everything, from individual percussion hits to full mixes. That said things with minimal dynamic range fluctuations such as pads don’t benefit as much from compression as things like vocals.

As mentioned above it’s like an automated volume control. The loud bits get quieter and the quiet bits get louder.
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vurt
addled muppet weed
54953 posts since 26 Jan, 2003 from through the looking glass

Re: Can someone explain to me the function of a compressor?

Post Thu Oct 17, 2019 1:10 am

[quote=Mozex post_id=7547538 time=1571295106 user_id=437597]cfanyc thank you thats very helpfull. I have a question to everyone: I assume I need to put this on my master bus?
[/quote]

some people and styles will use one on each individual track, subgroup and the master.
some people and styles dont use any, except maybe one on the master.
and then there are people and styles that fall in between.

a compressor can be useful anywhere, it's a bit boring so is often ignored but is a great tool to get to know. but it's not so straightforward as each use is dependent on the material and how far you want to push it.
sometimes you just want to tame the transients a little to stop clipping, sometimes you want to flatten it to boost the track for "oomph" :)

perfumer
KVRian
575 posts since 4 Oct, 2018

Re: Can someone explain to me the function of a compressor?

Post Thu Oct 17, 2019 1:31 am

Mozex wrote:
Wed Oct 16, 2019 10:54 pm
@jochicago I only have these compressors to my availablility (It are a few of the the plugins that are available in the all acces pass): https://www.slatedigital.com/virtual-analog-bundle/
Wow, you have the complete Slate bundle, and you don't know what a compressor is?

Just arrived from the n-dimension with your ma's credit card?

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Unaspected
KVRian
1057 posts since 4 May, 2012

Re: Can someone explain to me the function of a compressor?

Post Thu Oct 17, 2019 3:26 am

Above a preset threshold, a compressor attenuates the amplitude of a signal by a ratio.

This can result in increased perceived loudness, levelling, transient treatment, saturation, mix placement, pressure effects, etc. If the side-chain input is processed then the compressor can be tailored to behave differently so it may be used for tasks such as de-essing. Insertion of a second signal at the side-chain can then be used for ducking effects; where the second signal then triggers the compressor.

You're going to want to understand metering and gain staging before learning about compressors.

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Teksonik
KVRAF
12857 posts since 16 Sep, 2001 from Las Vegas,USA

Re: Can someone explain to me the function of a compressor?

Post Thu Oct 17, 2019 3:56 am

"Google it" = "I don't know the answer". :lol:
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el-bo (formerly ebow)
KVRAF
15300 posts since 24 May, 2009 from A galaxy, far far away

Re: Can someone explain to me the function of a compressor?

Post Thu Oct 17, 2019 4:41 am

Teksonik wrote:
Thu Oct 17, 2019 3:56 am
"Google it" = "I don't know the answer". :lol:
Nah. "Google it" means, "If you don't Google it, then I'm going to probably have to Google it for you, so that I can copy/paste the links (to videos, blog-posts, and thousands of links to similar threads on KVR) that you'd have already discovered if you'd only thought to Google it, beforehand" :shrug:

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