# When should I compress?



## liambrownpianopro (Aug 4, 2021)

Hi everyone, I am not a complete newbie but I have been in the game for about 4 years. I never got why people use Compression. I know that a compressor reduces dynamic range, making the louder bits quieter and the quiet bits louder and you can attack at different times depending on what you want. I do not currently use compression hardly ever, where would I need to use compression in a pop/orch/band tracks?


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## Ivan M. (Aug 4, 2021)

Same here, I rarely use compression, usually just a limiter on the finished track when pushing the loudness. I don't even like how compression sounds, it's better when the sound breathes. Would also like to hear how and when people use it


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## Wedge (Aug 4, 2021)

Many people here will know better than I. But I almost always use it, to atleast some degree, on the bottom end (kicks, bass, ect.) I find it just makes it easier to mix instruments into the space I want them. If I'm making a rock track I use compression on every part, just varying degrees depending on what instrument, so a clean guitar would have less than a distorted guitar. And it's always applied when mastering but the extant varies depending on the material. Rock/ metal I will use heavy compression, orchestral I'll user a lighter compression depending on the track and what I'm going for. So something with a classical feel would have a subtle amount, where something cinematic would have a bit more.


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## NekujaK (Aug 4, 2021)

Compression is one of the most powerful tools in your mixing arsenal. It's not only a technical tool, but a creative one that can significantly shape the sound of your mix. But like any tool, you need to know how to apply it properly.

Check out this excellent video about how to hear compression. There are lots of videos and tutorials on the web about using compression, but this video focuses on learning how to hear the effects of compression on individual parts in a mix. This is invaluable, because once you understand what compression is capable of, you'll be able to confidently determine how and when to use it. It's far more than just clamping down peaks and evening out parts.


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## liambrownpianopro (Aug 4, 2021)

Wedge said:


> Many people here will know better than I. But I almost always use it, to atleast some degree, on the bottom end (kicks, bass, ect.) I find it just makes it easier to mix instruments into the space I want them. If I'm making a rock track I use compression on every part, just varying degrees depending on what instrument, so a clean guitar would have less than a distorted guitar. And it's always applied when mastering but the extant varies depending on the material. Rock/ metal I will use heavy compression, orchestral I'll user a lighter compression depending on the track and what I'm going for. So something with a classical feel would have a subtle amount, where something cinematic would have a bit more.


so you would apply it to everything more or less even if just a tiny amount?


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## liambrownpianopro (Aug 4, 2021)

NekujaK said:


> Compression is one of the most powerful tools in your mixing arsenal. It's not only a technical tool, but a creative one that can significantly shape the sound of your mix. But like any tool, you need to know how to apply it properly.
> 
> Check out this excellent video about how to hear compression. There are lots of videos and tutorials on the web about using compression, but this video focuses on learning how to hear the effects of compression on individual parts in a mix. This is invaluable, because once you understand what compression is capable of, you'll be able to confidently determine how and when to use it. It's far more than just clamping down peaks and evening out parts.



brilliant thank you


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## el-bo (Aug 4, 2021)

liambrownpianopro said:


> Hi everyone, I am not a complete newbie but I have been in the game for about 4 years. I never got why people use Compression. I know that a compressor reduces dynamic range, making the louder bits quieter and the quiet bits louder and you can attack at different times depending on what you want. I do not currently use compression hardly ever, where would I need to use compression in a pop/orch/band tracks?


The idea of reducing dynamic-range seems quite a loaded term. It seems totally at odds with the idea of dynamic expression. But it needn't be.

I'm far from being an expert with any of this, and for most of my recording life I've not bothered with compression. It's a shame as I'm only now starting to realise how useful it is in terms of providing cohesion and intentionally adding dynamic where needed. Also, it's interesting to note the changes in the lilt and groove of a part, when using varying types and amounts of compression. And just like with other effects, it's these almost side-effects of the process that are more interesting than using them to make our wave-forms look all sausage-like.

I'm still a long way off being able to discern the smallest of details, but it's proving to be a fun journey.

Here's a different perspective:


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## liambrownpianopro (Aug 4, 2021)

el-bo said:


> The idea of reducing dynamic-range seems quite a loaded term. It seems totally at odds with the idea of dynamic expression. But it needn't be.
> 
> I'm far from being an expert with any of this, and for most of my recording life I've not bothered with compression. It's a shame as I'm only now starting to realise how useful it is in terms of providing cohesion and intentionally adding dynamic where needed. Also, it's interesting to note the changes in the lilt and groove of a part, when using varying types and amounts of compression. And just like with other effects, it's these almost side-effects of the process that are more interesting than using them to make our wave-forms look all sausage-like.
> 
> ...



I a loving this guys stuff, he has such a calm approach about his videos not screaming into a mic and telling people to buy his course.


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## el-bo (Aug 4, 2021)

liambrownpianopro said:


> I a loving this guys stuff, he has such a calm approach about his videos not screaming into a mic and telling people to buy his course.


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## Henu (Aug 4, 2021)

Very simply put, you compress for either 1) consistency (dynamic range limitation) or for 2) sound. 
If neither of the abovementioned is needed, you shouldn't fix what ain't broken.


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## Wedge (Aug 4, 2021)

liambrownpianopro said:


> so you would apply it to everything more or less even if just a tiny amount?


Henu above put it simply and perfectly. No I don't put it on everything. But I do put it a lot of instruments that involve the bottom end so that it's dynamic range isn't all over the place, but it's to varying degrees as needed. If I'm doing a classical piece, the violin1, 2, viola. are usually not compressed at all except maybe a tiny amount on the mastering chain. There's no hard rule with compression it's just what you feel the piece needs. If it doesn't need it, awesome!


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## jcrosby (Aug 4, 2021)

The choice to use compression should be purposeful. It could be technical - to reign in peaks... Or it could be aesthetic - to smooth out a performance, or add an increased sense of movement. All of these are sensible reasons to use compression.

Working with samples makes the technical _need_ to apply compression a bit less common since we typically have control over the dynamics and expression of a performance. When tracking though the technical reasons take a front seat like reducing peaks and dynamics... Basically it's all about learning how to apply it when it feels necessary or tasteful to you...

And I'm not implying you don't compress samples above, quite the opposite actually. I'm actually saying it becomes more of an aesthetic choice, and those choices could range from adding density, to injecting movement or energy, to enhancing sustain, even subtle tone chages..

But as mentioned above... Never underestimate the artistic/aesthetic/creative ways to apply compression... And like any kind of processing a good rule of thumb is - _Just becuase you can doesn't mean you should_...


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## Soundbed (Aug 4, 2021)

It’s not my most succinct video, but I recorded my thoughts one day when it was killing me to keep holding these words inside and not share them with others. 


(Someday I’d like to make a better version of this video.)


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## re-peat (Aug 4, 2021)

Henu said:


> Very simply put, you compress for either 1) consistency (dynamic range limitation) or for 2) sound.



There’s a third and *very* good reason to use compression and that’s if you want or need to inject some extra energy in sounds. Most often this would be anything percussive, but short articulations in the strings or the brass can benefit greatly from it too. (Woodwinds, especially the sampled variety, tend to be less suitable.)

Pizzicato sent through a compressor with just the right settings, can sound much more lively and bouncy. Brass stabs or any type of short exclamation in the strings can gain considerable impact if compressed correctly. If you want your snare to sound more like a whack rather than a mere hit, use (the right type of) compression. Bassdrum and toms can sound ten times as powerful with a well-judged amount of the right compression. There’s tons of things like that in music production. (Guitar chops are another excellent candidate.)

So this use of the compressor is not so much about keeping wayward dynamics under control but rather to "clench the fists of the audio a bit tighter", so to speak, in order to have it punch with more energy and focus (which can be of great, musically expressive value). Key in all of this are the settings for the Attack (should be slow-ish) and the Threshold of the compressor.

_


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## antames (Aug 4, 2021)

Compression just means turning down the volume. I use it on instruments that might be too bright or too harsh like brass, or in parts where a sound jumps out too much and needs to be tamed. For orchestral type of music you want to use it very subtly otherwise it will squash the sound too much. You ideally want to put the threshold to where the compressor just kicks in at the loudest part of the instrument or song so that it's only turning down the volume in those parts.


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## Chris Harper (Aug 5, 2021)

Compression definitely turns down the volume, but it’s also so much more than that, for the simple reason that it’s dynamic, and I mean that in the sense that the timing of the attack and release are variable. Someone said above they don’t like compression because they like the music to breathe. On the contrary, I would say that is one of the best reasons to use compression is precisely BECAUSE it can make the music breathe, but it’s a difficult skill to learn. The Kush After Hours video is an excellent demonstration of that. It’s really difficult to train your ears to hear mild compression, and big compression causes big distortion, which works in hip hop, EDM and high energy pop, but is obviously unpleasant for most orchestral applications.

Learning to hear compression, to me, was a huge change in the way I hear music in general. Just like learning to pick out individual instruments in a mix, it’s one of those things you can’t un-hear after you learn to hear it. You will forever notice it in every song you listen to, particularly master bus compression.

I use compression in some form on every single song I make, including orchestral.

Using it on a bus with percussion (including the master) can bring create an internal rhythm that actually makes mix breathe, especially on faster and more rhythmic songs. Gregory Scott’s video above is a fantastic demonstration of that. Sit in the dark with complete quiet and listen to that video closely. It’s excellent.

I use it a lot to control inconsistent frequencies, which you will find in every orchestral library. A double bass section patch almost always gets a multiband to treat the inconsistent low end that is an inherent part of multiple low end instruments playing together. The slightest difference in phase or resonance of the instrument or the room makes the low freqs pop out on some notes and not others, and the phase alignment issues between two basses playing together can be particularly problematic. A single band covering the low end of the patch tames those inconsistencies that muddy up a mix. De-essing sibilance is a similar concept. Both of these techniques are just pushing back a frequency that pops out of the mix repeatedly. Sometimes, I will even “de-ess” a violin or viola if there are inconsistencies in the high end that make certain notes sound harsher than others. With a multiband, you can remove the occasional harshness without taking the edge off the whole track by using an EQ. 

I use it to bring important parts forward in the mix. A vocal or a melody line that is more dynamic than the background music will get lost behind everything else, popping in and out of the listener’s attention. This is especially important on vocals, because you want the focus to be placed on hearing the lyrics. Of course with virtual instruments it’s usually best to simply adjust the midi, but compression can be useful at times as well. I’m thinking of things like hybrid with everything cranked to eleven.

I use it to shape notes. A slightly longer attack with a fast release brings the transients out in the mix. A shorter attack pushes the transients back into the mix if they are too powerful. Compressing the initial transient and using a longer release brings out the sustain of a plucked instrument.

I almost always use a very small amount of bus compression on my sub-mixes, and a very small amount on the master bus, which serves as “glue” that brings the final bit of cohesiveness to a mix. It’s kind of like a fine grit sandpaper after a final coat of paint.

Compression staging often works better than hitting everything harder with a single compressor or limiter. In this way, master bus compression works as kind of a pre-limiter. By adding that additional stage, you can minimize the distortion from the limiter, and also have more control than you can get from the limiter alone. Ideally, you have an absolutely flawless mix that goes through the limiter and comes out perfectly balanced on the other side. In reality, I’ve never had a completely flawless mix. There is always at least one little thing that causes an artifact from the limiter. Often adding a small compression stage right before the limiter can help smooth out the limiting artifacts much easier than mixing down 50 times to get it closer to perfect. It becomes like a game of “whack-a-mole”, with one adjustment in the mix affecting something else in a subtle way. If you aren’t pushing a limiter hard, it usually isn’t a problem, but it is almost essential if you are going to push a limiter hard.

The important thing about learning to use compression is that these changes are easier to hear within the context of the mix. In isolation, the effect is less obvious. It’s the relative volume against the mix that’s important. Most people will try to learn compression by soloing a channel, throwing on a compressor and tinkering to see what it does. This way, you can’t hear the subtle changes. Our brains are wired to ignore these subtle variations. You only hear it when it gets badly over-compressed. But in the mix, it’s more obvious.

I guess my main point is that there are a ton of ways to use compression, and even though it does effect volume, strictly speaking, it’s more than that, because adjusting volume over a millisecond scale changes the way our brains interpret the sound of the music differently than just a volume knob would. It can solve problems, for sure, but it’s also a creative tool that can make a dull track sparkle, add sheen to a track that’s almost there, or make a boring beat into an interesting groove. Of course, it can also ruin an entire song, which is why it’s best to really use modestly until you have more practice. I can say this having much personal experience at ruining things.


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## re-peat (Aug 5, 2021)

And then there’s *side-chaining*: controlling the compression of one track with another track. Most commonly, people use a kick to compress the bass so that every time there’s a kick, the bass ducks down a bit — a classic and widely used technique — but you can use it equally well for countless other purposes. Orchestrally too. For example, if you wanna make extra room for your often-difficult-to-mix big percussion hits, you could have those hits control the compression of the other sections. As in: when there are no hits, the orchestra remains uncompressed, but whenever there’s one of those big percussion hits, the level of all the non-percussive sections of the orchestra drops a bit. Done well, the compression itself should be inaudible, but you’ll hear a significant improvement in de-cluttered power and impact. Takes a bit of planning of course — percussion needs to be sent to a different bus than the other sections, and the bus of the former needs to be set up as the side-chain input for the compressor(s) inserted on the bus channel(s) of the others) — but worth it if that’s the kind of music you’re making.

Also meriting some consideration: *expansion*. That’s the opposite of compression and there’s two different types: upward and downward. The former increases the level of loud signals when they exceed a certain threshold, the latter reduces the level of audio when it drops below a certain threshold. In other words: loud gets louder and soft gets softer. Sometimes used to restore some suggestion of dynamics in an overly compressed track, but it’s got many other uses.

Can be used with side-chaining too. Here’s *a little example*. In this clip, the bassdrum is used as a side-chain input for an Expander which is set to lower the level of the StereoOut by about 10db. Everytime the bassdrum enters the Expander however, it’s making the Expander stop working so that the audio immediately jumps back to its original level, iow increases by 10dB. The result being that the rhythm and pulse of the audio become much more pronounced. (In a way that’s difficult to accomplish without an Expander.)
You can use this technique for all sorts of stuff, just make sure that you choose as your side-chaining source a signal that accentuates the defining beats of whatever rhythm you have going on. And if you don’t have a suitable track as part of your arrangement or orchestration, you can create an additional track with all the necessary accents, disable its output and simply use it for side-chaining purposes.

_


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## Henu (Aug 5, 2021)

re-peat said:


> There’s a third and *very* good reason to use compression and that’s if you want or need to inject some extra energy in sounds.


Yep, and in my head, that's already included in the part about "for the sound".


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## re-peat (Aug 5, 2021)

Ah, I see. Difficult to know what the unwritten thoughts in your head are of course. I wrote my reply assuming that by ‘the sound’ you meant the actual sound that many compressors will impart on the material they’re processing. Like a Fairchild sounding very different than an SSL Bus Compressor or a dbx 160 ... Which, come to think of it, is another very good and often used argument to bring a compressor into the mix: its characteristic colorization. More than a few mixing engineers insert their favourite compressor in the processing chains and set it to do … nothing. Or as good as nothing. It’s mainly there for the sound of its circuitry.

_


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## olsontex (Aug 5, 2021)

NekujaK said:


> Compression is one of the most powerful tools in your mixing arsenal. It's not only a technical tool, but a creative one that can significantly shape the sound of your mix. But like any tool, you need to know how to apply it properly.
> 
> Check out this excellent video about how to hear compression. There are lots of videos and tutorials on the web about using compression, but this video focuses on learning how to hear the effects of compression on individual parts in a mix. This is invaluable, because once you understand what compression is capable of, you'll be able to confidently determine how and when to use it. It's far more than just clamping down peaks and evening out parts.



A lot of the basics and some creative uses have been covered by other posters (good stuff). There are three topics that weren't emphasized as much as their relative importance to me. I'm going to address #1 in some detail but largely ignore #2 and #3 in this post.

First a question for anyone who considers a compressor simply a volume control. When you turn down the volume on your car stereo, does it turn down all the notes and instruments or just the really loud ones? I know, dumb question right! Well unlike the volume control on your stereo, your compressor doesn't lower the softer notes and instruments that fall below the threshold, only the loud ones above the threshold. I don't want to expand this discussion into what loudness is or how you raise the loudness of your song to a commercially competitive level, but suffice to say you aren't getting there without compression and its' cousin the limiter.

1) role of compressors for controlling (taming) or designing (shaping) transients. Yes, there are some nice transient shapers out there and I use them too. It would be a mistake though to think they can substitute for a compressor.
2) the "c" word (adding harmonic content to mimic a bit of the tonality of transistors, vac tubes, etc. found in analog gear). If you aren't incorporating any analog gear, adding a few emulations can add some of the "w" word. The impact is in the same family as saturation but it's not exactly the same.
3) there are 4 primary types of compressors (VCA, Fet, Optical, and Tube). They have distinctly different characteristics, tonal footprints, and relative strengths/weaknesses for specific instrument types and uses. It's not enough to know how to use a compressor, it's also important to know which type of compressor will work best for your application.

Something else that 100% jumped out at me. There seem to be significantly different viewpoints on use-cases and relative importance of compression between composer/orchestra types and pop/rock/band types. These different perspectives are why I like VI forum so much more than any other similar community out there. I'm going to express this in terms of someone with predominantly an orchestral background (not me), but the script could be easily flipped to focus on what a pop/rock/band type doesn't understand about dynamics and transients in an orchestral setting.

Speaking in generalities, if someone's background is almost entirely orchestra they might think about drums more in terms of percussion. They would expect the percussionist to be skilled at controlling their volume (or programming velocity) to not overpower lower output instruments. At the other end, crescendos can be highly reliant on percussion to reach the peak, and in most cases reducing dynamics is not desirable. Perhaps a source for some thinking about compression as primarily a volume control might be the natural compression a performer provides by controlling their attack and release. I think there is also a higher level of masking occurring in a full orchestra setting (vs. a 4 piece rock band), which not only impacts competing frequencies but also somewhat reduces the impact of transients (there's a natural gluing effect too). For this reason, they might not see the big deal about controlling transients in other settings. It might catch them off guard how challenging it is sometimes to record and place an acoustic rhythm guitar part in a mix without a bit of light compression, or that the likelihood of capturing the individually mic'ed drum kit tracks as "mix ready" without the use of compression approaches nil. 

I want to emphasize a handful of points before closing out.

1) Purpose based tool - if you are tacking on a comp because you think you're supposed to, stop. Your track may very well benefit from compression, but if you're not using it in a targeted manner then you're likely to do more harm than good. You might suck all the life and energy out of a track or you might crush the peaks and pull up the valleys to a point of removing the sonic beauty from an instrument. Or it might just sound terrible in general because you don't know how to set the threshold, attack, and release within the context of the SPECIFIC song you're recording/mixing.

2) Beware of using presets - I like presets, presets can be a good STARTING POINT, especially if you don't know where to begin. A typical compressor has 5 controls, and only 1 of them has some general guidelines for use scenarios. It's the ratio setting, and even then there are no absolutes. As an example, a ratio of 4-1 or 3-1 is usually pretty safe for acoustic guitars. The other 4 are attack, release, threshold, and knee.
Attack - a stylistic choice for how controlled, punchy, tight, etc. you want your track to be (how quickly it catches the peaks)
Release - how long the note is kept compressed (huge impact on both tone and groove)
Threshold - entirely dependent on the db recording level of your track (when does it kick in)
Knee - how aggressive you want the compression to be (smooth -> to abrupt)

Whoever designed the preset couldn't possibly know the perfect mix of these interrelated controls for your specific application. Nothing wrong with using a preset to get you in the ballpark, but there's no substitute for learning how to use these controls to have any shot at a mix approaching a professional level. When you hear the phrase "learning to hear compression", that audible cue occurs at a different specific point when moving the dials for every song.

3) Comp for physical instruments - the first line of defense for controlling dynamics is your hands or your mouth (I guess feet too). I consider this a core element of technique on an instrument. However, a portion of your control is lost when an instrument is amplified. Equally important, is the control or shaping of transients. I think of transients as a)the decaying sound between notes and b) the initial strike of the next note. If someone has a better way to word this please have at it. The thing about transients is they are a crucial element for establishing the groove, feel, or whatever word you want to use for getting toes tapping and heads bobbing. A lack of groove isn't the worst possible outcome for letting your transients run rampant. Transients that are too aggressive, out of sync, or focusing too much in an unpleasant frequency range will be distracting and noticeable in a bad way.


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## olsontex (Aug 5, 2021)

After writing all that I forgot to mention the entire reason I was posting in the first place. There are many really helpful videos out there about using compression, but I think Gregory Scott (House of Kush) arguably makes the best ones for people getting stuck/frustrated in application. In addition to the ones posted in this thread, go back at least a year because his intros during the earlier stage of the pandemic are pretty funny.

Kush makes excellent hardware but they also make some really useful (and mostly uncomplicated) plugins. I've got 6 of them and they all see regular use. Well, 5 do and 1 is about to, as the new finishing EQ (Blyss) is outstanding. I really really really didn't want to buy another EQ plugin but Blyss is different. I trialed it on my latest mix and when the trial ran out today, there was no way I was going to lose the enhancements it made on this song.


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## Tralen (Aug 5, 2021)

I don't know if this has been mentioned, but as users of sample libraries, we have to deal with the differences in dynamics between them. Sometimes the very same part played with different libraries can have wildly different dynamic ranges, specially if the dynamics are baked in the articulation, so compression can help to blend the libraries together.

Also, sometimes the relationship between timbre and dynamics in a particular instrument can be skewed in an unpleasant manner, and it is useful to compress it to center the timbre where you want.


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## jcrosby (Aug 5, 2021)

Tralen said:


> I don't know if this has been mentioned, but as users of sample libraries, we have to deal with the differences in dynamics between them. Sometimes the very same part played with different libraries can have wildly different dynamic ranges, specially if the dynamics are baked in the articulation, so compression can help to blend the libraries together.
> 
> Also, sometimes the relationship between timbre and dynamics in a particular instrument can be skewed in an unpleasant manner, and it is useful to compress it to center the timbre where you want.


100%. Short articulations especially can have a wide range of differences from dev to dev, library to library... if blending libraries from different developers it’s pretty common for me to add a little compression on the bus to create a sense of cohesiveness. (Short strings especially so...)


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