Using Compression: What Does Compression Actually Do?
Posted on January 18th, 2013 by GratuiTousIn Questions/Thinkers | No Comments »
Audio Compression within Beats,
One of the most misunderstood things inside mixing! (And mastering).
What does compression actually do? How does compression work? What are the benefits of compression?
Long story short, compression is used to bring down the loud parts of your song/instrument to keep them move even with your quiet parts. It does this by lowering the peaks.
Why you’d want to use compression while mixing is:
- To make your overall master louder, since you’ve dealt with most of the peaks during your mix
- Sometimes things just can’t stand out / fit nicely without compression.
But don’t over do your compression, as this can make the track sound “lifeless”, taking out lots of the dynamic range. (More on that below!)
Too Much Compression — The Negatives,
I will talk about some negatives to compression before the benefits to get you thinking “Do you even need to use compression?”.
If you are using compression on vocals, what you have to be aware of is compression will bring up the quiet parts, and guess what are in the quiet parts of your audio when you record?
Computer fan, furnace heater, movement of the paper with the lyrics on it — you get the point.
So when compressing down the loud parts to make them “more equal to the quiet” parts, these are things you have to be aware of. It can also bring out the breathes in your vocal a lot more noticeably, plus the clicks and pops in our mouth’s as we speak!
Another thing to mention is the ESSes in vocals become more prominent if you compress before De-Essing first. This is because the Ess sound in our voices doesn’t change too much in volume compared to other words/sounds. So if you compress a loud word, it will bring the volume down closer to the quiet word. But the ESS sounds are usually not that loud on your vocal recording, while looking at it, but while hearing it, it’s very sharp and piercing. If you compress, it brings the loud parts closer to these ESS sounds, and therefore have an annoying vocal. Try De-essing before compressing to prevent the harsh esses!
But the benefits to using compression with vocals would be to keep the vocal more consistent throughout the track, allowing the vocal to sit at a nice level throughout the verse, chorus etc.
Now, that’s just recording vocals,
Compression on Individual Instruments, and On Your Over All Master Bus?
It’s still a similar approach; keeping the instruments more consistent in level throughout the song. But there has been abuse by using compression just for the sake of loudness rather than clarity or helping you to bring out certain tracks in the mix, not allowing them to get buried!
Now this is where The Loudness Wars come in. They take advantage of compression and other techniques to boost up their overall level so loud, that in the end it leaves you with a big blob in your master looking like this:
Rather than something with peaks like this! (Notice the intro and outro in the second image)
No Dynamic Range — Why It’s Bad,
This leaves no dynamics in your song.
What does dynamic range mean?
Think of it this way, if your track is like the first image (the blob), your quiet parts that were suppose to be quiet, are now suddenly just as loud as your chorus! This doesn’t give much of a change up towards your chorus when it comes to volume. Choruses are usually a bit louder than the verses, giving them that big, epic impact. But with the master pushed so hard, you lose that impact of volume change, therefore having no dynamic range.
So, dynamic range, simply put, is the loudest peak of your song compared to the lowest peak.
Below, I’ve uploaded both versions of the beat from the images above. The first one, I boosted.. by quite a lot ;).
If you are ever comparing tracks, such as a compressed track verse a non-compressed track, or an EQ’d track verse the original track, level matching is very important to hear the differences you are actually making to the song. This is making sure the volumes are the same level, so when you go between them you hear them at the same volume. Why? Cause louder always sounds better, and we tend to lean towards the louder master. So level match, and compare for yourself!
(Pushed really hard version — Barely any dynamics)
(More acceptable version with peaks)
Surprisingly though, the super loud master does not sound “as bad” as I would of hoped for in this example 😉 — But you can still tell that the beginning is pretty much just as loud as the chorus, plus the loud version above here has a “pumping” effect” from pushing the mix so hard into the limiter.
A good example of this “pumping” is at 3:02. Put the track above at 3:02, then put the bottom one at 3:02. Click play in between them to compare.
Although the levels are not matched, you can still hear the “pumping” from “over driving” that limiter! (Also at 1:15, you can hear the white noise building, then the kick comes in and you can hear the white noise gets quiet for a second (pumping, think of like “side chaining”, but a bad side chaining lol).
FREE BEATS By GratuiTous Vol. 2 — Now Released!
Also, the beat used in this video was off my FREE BEATS By GratuiTous Vol. 2.
I now have a couple volumes out, just free download for your listening purposes.
Feel free to download, and enjoy 😉
Limiters, How Hard Should We Push Our Limiters?
Well from that first version of the beat (the blob), you can hear, I got away with a fair bit and the beat wasn’t “totally” destroyed.. However, it was still pretty bad, with some noticeable distortion on the kicks. So I guess hear with your ears! — The first version had about 10-15dB gain reduction, that’s huge lol (Gain reduction being, the peak going over the limiter).
The second version has about 2-3dB gain reduction, and while comparing the tracks at times I feel I could of pushed it maybe even a bit louder.. but I wanted to keep the beat very transparent and lots of change in the audio when the chorus comes in etc. (Still learning all this as well, but definitely have a pretty solid grasp on what I’m trying to achieve while doing it).
Reading Ian Shepherd’s post about limiters will really help some of you out:
Dynamic Range — More in Depth,
To make it easy for you to understand, dynamic range means the loudest part of your track when comparing to the most quiet part of the track. I guess you can think of it from your LOUDEST PEAK to your quietest one. Although Wikipedia always has the more “technical information”, which you can read here.
So overall, if you push your master too loud, your quiet parts aren’t going to match how you mixed the track, plus, when the chorus comes in, it won’t have “as big of an impact” because there’s no real “gain/volume increase”, you’ve pretty much just transferred from one section of the song to the other with the same volume.
If you remember from my tutorial on How to Arrange a Song (Or Beat), I said “if you add in instruments, that doesn’t necessarily mean you are building up to a big, powerful chorus. You need transitions, such as snare rolls, sfx etc. to build that big chorus.”
In the same way with mastering; if your master is too loud, guess what? There’s not “that big of an impact” from your verse to chorus because the volume is pretty much the same!
So this is just something to be aware of with compression and mastering, as compression allows you to do this stuff!
Not All Your Sounds Need COMPRESSION!
Just bear in mind, not everything needs compression, although compression can many times benefit a track. But always A/B (compare) your sound with “equal volumes”. Is your compression helping, or making it worse?
While mixing, think to yourself.. Does the sound stand out by itself? Would maybe just doing some cuts to EQ on other instruments fix my problem? What about some panning?
Concluding Thoughts on Compression,
If compression is used correctly and sparingly, it will help your tracks more “consistent”, making them audible throughout the mix.
Compression will also help make your overall mix “louder”, because you’ve dealt with a lot of the peaks in the mix, therefore, you can now push your master a bit louder!
There are also some cool techniques you can use with compression such as sidechain compression and parallel compression.
I may make some videos on those.. but there are so many already. I’d have to think of something creative with them that I feel would benefit you! 😉
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