If you're a music producer building up tracks—either for yourself or for another artist—then you've probably been bitten by the compression bug. Slamming that audio is a surefire way to give your sounds the heft and punch they deserve, right?
Turns out, maybe not: On the road to dynamic glory, there are many compression pitfalls you can easily stumble over. Here you will find eight of them, listed in no particular order. If you find you're guilty of any of the following, don't worry—so am I; so are we all.
In this piece you’ll learn:
How to identify common compression mistakes in mixing
Compression techniques that will enhance your tracks rather than hurt them
Alternative methods to using compression in your mix to create a polished sound
As you follow along, try out these compression tips and tricks with a free trial of iZotope’s Music Production Suite Pro that includes innovative mixing and mastering plug-ins like Ozone, Neutron, and more.
1. Unmusical compression on the way in
Notice I did not write, “compression on the way in,” for many engineers compress vocals, guitars, drums, and a plethora of other instruments as they record (I know I do). This problem resides in unmusical compression—compression that does not suit the material. Unfortunately, this is a frequent mistake I see in unseasoned producers. I’m thinking specifically of vocals squeezed to the point of maximum sibilance (that’s a common side effect), or basses squashed so hard that every note sounds dull in its evenness.
This mistake could take root in the old “set it and forget it” mentality—certainly an attractive mindset if you're new to recording: a piece of hardware that might just guarantee against distorting audio on the way in? Sold! All those fantastic emulations at your fingertips! All those preamps to juice! The temptation could be overwhelming.
Conversely, if you're working with dedicated units over all-in-one interfaces, the love for your boutique preamp could be the culprit—I certainly know my API 3124 sounds great when juiced, but the converter seems to have a problem with the peaks. Enter the compressor, which clamps the transient, often creating unpleasant timbres in its wake.
Allow me to be candid and vulnerable and present a recording I made of myself from 2005, when I had a) more hair and b) no idea how to use my API 3124 or my API 2500, or really, anything. This recording evinces unmusical compression on the synths, drums, bass, and guitar. Oh, and it’s been limited to boot. It represents the pinnacle in unmusical over-compression. Enjoy!
Audio Example of Overcompression
Don’t sound like this, my friend. Instead, go for a happy medium: Don't juice the preamp, and compress musically and conservatively. Don't think of a compressor as a police officer providing a barricade against overloads, but as a bouncer who sometimes doesn't make the right call when ejecting customers from the club. And you don't need to fill the meters either; in 24-bit recording, there's little reason for that.
If you do crave the sound of your preamp, compensate afterwards. Put a well-built attenuator on the way out, or ride the output gain once you learn the ins and outs of the performance. Riding the output gain is actually a time-honored, time-honed skill. It takes practice, but if you learn how to ride the output gain as you would an instrument, using your moves to complement the audio (as a piano would “comp” a soloist in a jazz tune, for instance), you can enhance the performance being recorded—and protect it from overs to boot.
2. Slapping on compression “just because”
In the age of digital recall and project templates, it’s easy to have your plug-ins lined up before you’ve imported audio. But reaching for the compressor just because it’s there causes problems. It can foster wanton abandon—a willy-nilly approach both dangerous and unmusical—and we can lose sight of the groove, the feel, and the rest of the intangibles.
We also risk losing our creativity: Are we painting by numbers here, or is there a reason to compress this vocal? What if it’s better to lower the volume of everything else? We can’t make that decision without careful consideration.
Mixing is balance, and unwarranted compression can tip this balance. When you squash the peak, sure, you can raise the level—but before you know it, the quiet sounds are loud, the depth of field is sacrificed, and the width of processed stereo elements is compromised.
As an example, take this mix, off the record America’s Got Talons by the band Adjective Animal. It’s already got a fair amount of luscious compression, both of the dynamics-restriction kind and the character variety. Observe:
"Washing Machine" Mix
Now I will apply some truly terrible bus compression across the whole mix, with the following abusive settings:
"Washing Machine" Bad Compression Audio Example
It may sound fine at first, but consider that it’s about 7 dB louder than the original—and anything louder is usually perceived as better. Let’s reduce the settings and give it another listen with the original mix in mind:
"Washing Machine" Bad Compression, Level Matched
Any groove in that high hat has been destroyed. The mix also “feels” narrower, which we can notice by focusing our attention on the guitars. Lastly, there is a fair amount of audible and bad distortion; this just won’t do.
All of this is because we’re adding willy-nilly compression “just ‘cause.” The mix is already plenty flavorful. If I want to bring the level up 7 – 8 dB, a much better approach, in this just to raise the fader or add a trim/gain plug-in. I can do so, and it won’t even clip:
"Washing Machine" Gain Added
Listen to how much better than sounds—yet we as mixers or producers often reach for compressors out of habit. Stop that!
Don’t compress just because you find yourself with five Fairchild emulations and a rainy afternoon!
3. Improper attack and release
This common problem affects even experienced engineers: I’ve received masters where the compressor’s attack and release fought against the groove of my mix on more than one or six occasions.
It’s a pity, because improper use of attack and release can take a glorious sound and smother it to death, while proper settings can pleasantly emphasize the rhythm as they tame the peaks.
Years ago, after much research and experimentation, I went with the following technique—and I've been happy with the results:
With a quick release, a moderate ratio (for the application), and a low threshold (not too low—you should still see some bounce-back on the meters), I fine tune the attack until I like how it's clamping down. Then, I work on getting the release to a place where I like how the signal returns to its original state.
Let’s use “Washing Machine” again, from the previous example. First, I brought down the threshold to -40 dB or so, which is a lot. As this was a stereo bus application, I chose 2:1 for my ratio (If it were drums or bass, and I wanted to show a more obvious hand, I would choose something around 4:1). Then I played with attack and release until I got the bounce I wanted. This is what we wound up with:
"Washing Machine" Tuning Compressor
The trick here is that I don't care about pumping at this stage. In fact, I want pumping. I want to love how it's pumping.
I listen for any musical feel that the compressor imparts in this exaggerated state, and once I hear something I like, I bring the ratio lower and lower—past where I’d want it, just to make doubly sure. Finally, I swing back to the sweet spot, which in this case, sounds like this at -20.8 dB:
"Washing Machine" Compressed with Good Threshold Settings
Threshold comes next, with the following tip:
4. Improper thresholds can reduce the quality of your mix
With the threshold point set too high, you're basically using a compressor for its tonal characteristics (which is fine, if that's your intent—but often it isn’t). Set it too low, and you run the risk of squashing too much dynamic movement.
There is a goldilocks point for every audio source, and it can be categorized in a couple of ways:
- The action point, around which the audio begins to bounce in a pleasant manner.
- The ceiling point, above which all sudden spikes come down to a reasonable strength.
The former conceptualization works better across groups of instruments, while the latter seems better for individual, “poky” sound-sources—vocals, basses with sudden spikes, et cetera.
The first step is to know which one you’re going for. Here’s a drum bus, for example:
Drum Bus Audio Example
In this instance, I’m going to want to find option A: the action point, around which the audio begins to bounce or dance in a pleasant manner.
But with this bass part, some of the notes are louder than others:
Bass Audio Example
So here, I want to go for option B: I want to bring down the loudest notes, musically, which will result in a more even bass part in the mix.
In either case, I can use a similar technique to really hear the right threshold setting:
First, I tend to my attack, release, and ratio settings in the manner described in the previous tip. I note my settings, or “copy” them within the plug-in’s menu. Then, I dial in a medium attack, a medium release, but leave the ratio the same; this can allow me to listen more to what the threshold is doing, rather than what the attack and release times are doing.
Now, as I adjust the threshold, it’ll be easier to hear where this “action” or “ceiling” point is located.
Here are examples of me fine-tuning each process, both for the drums and the bass. Let’s start with the bass:
You’ll notice on this bass recording, I used Nectar, which is nominally for vocals. I prefer Nectar on bass, so that’s why I did that, if you were wondering. Yes, I am a rule breaker.
Don’t forget to return to your original attack, release, and ratio settings when you’re done. In time, you’ll be able to hear the threshold more clearly, despite what the attack and release controls are doing, and you won’t even need this tip any more. You’ll be able to do it all with one go. But it still pays to use it as a way of drilling how to hear the best threshold setting.
5. Compressing an already-compressed sound
Remember, the sound in your session might’ve been compressed already—and not just by the engineer. A distorted electric guitar is compressed by virtue of its overdrive. Likewise, most synth patches have already been treated by the producer. They might come to you with compression, but they definitely arrive at your digital doorstep with their envelopes and LFOs finely-tuned for maximum impact. Your compression could negatively impact these parameters. If you're working from a sample, well, it’s probably been processed too.
You might be noticing a theme here—yes, the “don't overdo it on the compression” mantra might be wearing thin—but it’s simply the biggest trap when learning how to tame dynamics. I know I certainly fell victim to this practice in my engineering infancy.
So here’s an exercise to get you speedily over the hump: Take a track (any track will do) and squash it to the point where you can easily hear that it's too squashed. Now study the aspects of its timbre, so that you drill down on what too much compression sounds like. Home in, specifically, on resulting tonal changes that might be unfavorable, or unmusical changes in the feel/groove. Now dial all the settings back halfway or so, and listen again. This time, switch between bypassed signal and instantiated sound when listening. Upon hearing the compressed signal, do you recognize any tell-tales of over-compression? Keep playing around with the ratio of these settings until you start to notice when things sound just right. Then, when you do make the call to compress any instrument, you’ll know exactly why.
By all means, compress. But do so smartly: consider all these variables before compressing, because you could end up fighting against the quintessence of the sound.
6. Placing the compressor improperly in the chain
Pick an engineer’s brain and you might very well hear an absolute statement like, “I always EQ into my compressor," or, "I always compress into an EQ,” or occasionally, “I do all my cuts, then compress, then do all my boosts.”
All of these tactics are fine, provided the sound calls for the tactic. You have to be the judge of which tactic is the best. The big sin here—and consequently, the big mistake—is to subscribe in totem to one process over the other. To be foolishly consistent, as Oscar Wilde says, is the hobgoblin of small minds.
The order of processing should depend on the processors you’re using, the source material, and most importantly, what you wish to achieve in a given operation. Take the drums we showed off earlier. Let’s say we slap some drastic EQ settings across them:
If we place the compressor before these EQs, it sounds like this:
Compression Before EQ
But if we place the compressor after the EQs, we get a different flavor, because the EQ now changes the nature of which sonic information is slamming into the threshold.
Compression After EQ
Pop quiz: which one sounds better?
- Comp before EQ
- Comp after EQ
- This is a trick question; I can’t possibly know the answer unless I heard it in the mix
The answer is 3! What you do with a sound source depends entirely on the circumstances. It’s the sound that matters, not your approach, not your ideology.
7. Using multiband as a shortcut to “loudness”
In this instant gratification world, where so-called “radio ready” mixes are expected quickly, multiband compression can cut a quick path up the mountain of loud. It allows you, in theory, to skip massaging individual tracks in favor of processing whole busses, dynamically taming wide swaths of frequencies in the service of pushing the level.
In my earlier days, I certainly fell victim to this practice. I had a partner in top-line crime out in LA, and on our mix-buss, we would slap on a round of EQ, compression, and multiband, followed by another round of EQ, compression, and multiband—all of it driving a limiter.
Was it loud? Absolutely. Was it good? Far from it: Every sound was constricted in an unmusical box. And the groove? Decimated. The loudness only served to make people turn down the mixes, till our petty sounds screamed nasally at even the quietest settings.
This is a pitfall of multiband dynamics processing, be it of the traditional kind, or the dynamic EQs more prevalent these days. I’m not saying avoid multiband like the plague. Instead, learn the intrinsic strengths, weaknesses, and rules. For instance, if I have a vocal with too much meat in it, EQ might not do the trick. Knocking out the low midrange could kill all the body outright. A multiband compressor with a slow attack time on the offending frequency band might be just the ticket. Now the transient of the warmth can peek through, giving you the illusion that the frequency is louder than it is. You'd get all the warmth and none of the mud.
The takeaway: Pay attention to what multiband processing is doing to your signal—particularly at the crossover points—and you’ll get more mileage out of the technique, rather than complete sonic annihilation.
8. Compressing by meter instead of by ear
If you're just diving into the realm of mixing, meters are useful, both in our practice and in the learning of our craft. I would never advise to ignore your meters, but I wouldn’t trust them over your ears either. For instance, in analog gear, VU meters can often be slow to track gain reduction: your analog VU could read -2 or -3 in gain-reduction, when in reality the signal has been compressed far before the meter noticed.
As always, you must consider the music, and oftentimes, devoting yourself to the meter can sabotage what’s actually happening in the tune.
An example: I tend set up my stereo-buss compressor to give me -1 dB of gain-reduction on the VU, because largely, it works for me. But I could be deeply into the mix, really enjoying the balance, and when I look over, the needle is hitting way harder. My immediate inclination is to dial back the compressor when I notice this—but hold on a minute; should I? What are my ears telling me? I take a minute, close my eyes and listen, then get up, take a walk around the room. If the ears say 4 decibels of gain-reduction in this mix work, then who am I to argue?
Lessons learned about compression
This list comprises what I judge to be the biggest errors in the compression of audio. For many of them, I’ve provided tips on how to sidestep the pitfalls. Yet you might notice a conundrum here—many of these methods rely on your ears being the best judge, which begs the question: “How do you judge if your ears are any good?”
Well, your ears are like any other sensory preceptor in that they must be trained. Listening to records with an analytical ear for compression can help you in your training, as can giving yourself exercises based around these ten frequent offenders.
Pro tip: If you haven’t yet, start a free trial of iZotope’s Music Production Suite Pro to try out these compression tips with the plug-ins featured here, including Ozone, Neutron, Nectar, and more.
A final thought: You might go back to old mixes and realize that if you had to do it over again, you'd handle the dynamics differently. That’s perfectly normal—and it’s perfectly okay! Mixing is a dynamic process; you can’t expect to compress every technique into your head at once.
…See what I did there?