The Best Compressor Plugins for Mix Bus (With Audio Examples)

To many of us, the stereo bus compressor has become an important, if not indispensable tool in our mixing workflow. It’s almost as if we can’t truly “complete” a mix until we’ve applied the magic dust that our favorite comp seems to impart.

I am as guilty as any of sometimes relying on stereo bus compression as a crutch of sorts—though the benefits are undeniably real. My use (and love) of a good 2-mix compressor didn’t develop overnight, and in the beginning, it didn’t always seem to help in the way I expected it to.

Over time however, I realized that strapping a good compressor across the main mix provided a bit of sheen that I could not achieve by automating faders alone. It may not be “magic”, but it can be pretty damn cool.

Below, we’ll take a look at a range of some of the best and most popular options available today, to help you hear the differences for yourself and pick your own favorites.

What Makes for a Good Mix Bus Compressor?

The tricky thing about 2-mix compressors (as in with things audio) is that everyone has very specific and often idiosyncratic preferences. These preferences are formed as much by how each of us use the compressor and what kind of impact we expect the compressor to offer to the mix.

Many engineers think of a stereo bus compressor as something that forms a large part of the impact and aggressiveness of the mix, and will set the compressor accordingly, using as much as 4-6dB of gain reduction at all times. Others prefer to just use it for very gentle and transparent level control, while perhaps adding a bit of density to the mix. Both of these approaches are valid, and can yield results that are exciting and effective.

I tend to live in the “gentle and transparent” camp and have always had a hard time really digging way into a main mix compressor without feeling like something is being taken away from the mix. By contrast, I know people who use theirs more aggressively and would argue that hearing it working is the point of using it in the first place. To each his own, right?

Here’s a quick glance at all the compressors in the running. More on each in a moment:

“The Same, But Different”

When I set up this shootout, I had a clear process in mind and was pretty sure I knew what kind of result I would achieve. I have a bunch of 2-mix-worthy comps at my disposal and have used them all at one point or another with some success, so it knew it wouldn’t be hard to clearly show what each one does on the same piece of music.

I painstakingly set up each compressor as identically as possible, with regards to threshold, ratio, and attack and release times. I used a 400Hz tone to make sure they were all nearly identical in terms of gain reduction and output level. I had to ensure that my assessment was as objective as possible so that you could know that I wasn’t just trying to steer you toward what I prefer.

Once I had setup all 11 compressors to a very gentle setting (about 1dB of gain reduction) I was a bit surprised. When they’re barely working, the differences between them all were somewhat insignificant. There were definitely subtle variations in tone, but for the most part it wasn’t black and white, like “this one sounds the best”, or “this one will never work”.

It makes sense that the character of a compressor is defined largely by the sound of its gain reduction scheme and circuit, so naturally, the more you use it, the more it reveals. In essence, a shootout that doesn’t explore a compressor audibly compressing would be of little use to someone who wants to compare the differences between different models and types of compressor.

So, I modified my approach and came up with a better plan:

As an additional test, I figured it would be more useful to try the compressors on a few different types of music and then curate things a little bit by selecting only the ones that performed the best for that specific task.

This was meant to keep you from having to listen through all 11 different samples that are only subtly different while trying to maintain any perspective. It’s hard to hold that many sounds in your head at once, especially when the differences are minute, so that didn’t sound too productive to me. (But for those of you who want to really nerd out, I’ve also attached all the samples for download.)

While I would still test each compressor in the normal (for me), transparent manner, I also did my best to use the compressors in ways that are atypical of my approach, compressing the mix more aggressively. It was eye-opening (ear-opening?) to say the least!

In the end, all of the compressors I tested performed adequately—if not exceptionally—on all of the program material I tested with. But for brevity’s sake it made more sense to focus on the very best performers for each style of music.

The Participants

I have quite a few of these “compressor” things at my disposal, and they represent a pretty good cross-section of what is most commonly used by professionals across many genres. All the major bases are pretty well covered here, including:

Manley Variable-Mu by Universal Audio – $299.00

This is an emulation of the famous all-tube compressor by Manley which employs the same gain-reduction method as a Fairchild 670.

It has a 1.5:1 ratio in “compress” mode and goes from 4:1 to 20:1 in limit mode, depending on the amount of gain reduction applied.

Elysia Alpha Master by Plugin Alliance (also available for UAD) – $299.00

This is an emulation of the Elysia mastering compressor, renowned for its ultra-high-quality Class A signal path and gain reduction circuit. It can operate in Feedback or Feed-Forward modes which makes it extremely versatile.

Brainworx Vertigo VSC-2 by Plugin Alliance – $299.00

This is an emulation of the Vertigo VSC-2 VCA based compressor.

It’s much like a classic SSL buss compressor with a couple more ratio settings and an all-discrete, mastering-grade signal path.

Chandler Limited Zener Limiter by Softube (also available for UAD) – $299.00

This is an emulation of the Chandler version of the Abbey Road/EMI limiters from the late 60’s and early 70’s, with a very colored, but musical, signal path.

The plugin version has been adapted and updated from the original designs to make it more versatile, consistently useful and modern.

Virtual Buss Compressors by Slate Digital – $149.00

This is a bundle of popular buss compressors offered by Slate Digital that includes three distinct models, each with a different tone:

The FG Red is modeled after the transparent Focusrite Red compressor, with a few added features. The FG Mu is modeled after the Fairchild 670 and adds some more versatility with fully variable attack and release times. The FG Grey is modeled after the classic SSL 4000 buss compressor.

Shadow Hills Mastering Compressor by Universal Audio – $299.00

This beast of a plugin is based on a beast of a hardware unit that carries the same name. It is comprised of an optical compressor and a VCA compressor in series.

In addition to these two stages of compression, it has three switchable output transformers—”Nickel”, “Iron” and “Steel”—and a built-in sidechain filter.

Fairchild Tube Limiter Collection by Universal Audio – $299.00

This emulation was an update of the already great Fairchild 670 from UAD.

In this bundle, they added new features like a variable sidechain filter and a headroom control trimmer, while retaining the legendary Fairchild tone.

Kotelnikov Mastering Compressor by Tokyo Dawn Labs – Free!

This is a remarkably transparent compressor that models nothing in the real world, and is free.

The “Gentleman’s Version” is €40 and adds a few useful features like an external sidechain, “insane quality” mode and equal loudness bypass and more.

MJUC by Klanghelm – $25.50

This incredibly affordable software compressor from Klanghelm includes 3 separate and distinct models:

The Mk1 is a model of the Fairchild 670 with a few unique features added. The Mk2 models the UREI 175 or 176, also with a few unique features added. The Mk3 is Klanghelm’s proprietary take on vari-mu compression with a more modern twist.

Test A: Transparent Level Control

I started with the mode that was most comfortable for me, which is where the compressor is barely working.

When used this way, I rely on compressors that have a clean signal path and a transparent way of controlling the mix that is subtle yet effective. For the most part, I am using a low ratio of 2:1, or less if available.

I find that tube compressors are usually better for this task, simply because of the gentle rounding of transients that occurs when you drive a tube circuit even slightly. This tube “shaping” works like having an almost-invisible compressor in front of your compressor. It’s similar to the way that tape can add RMS level to your mix without apparently changing the mix. (Though of course, it is changing it.)

For the first test, I used a song from The March Divide, with whom I just completed a record. It’s acoustically-driven, singer/songwriter type of music, which is dynamic and clear, with lots of acoustic percussion. The song is called “I’m Not Sorry” and you can check out the band at their website, themarchdivide.com. This record is slated for release sometime in mid-2017.

On this song, I was careful to not clamp down much at all on the loud parts, particularly because the verses are quieter, and I still want the chorus to “lift”. Too much compression would have the reverse effect.

For the most part, during the loudest section of the song (in this case the chorus) I am only compressing about 1dB, with an occasional bump to 1.5dB. Subsequently, the verses are barely compressed at all.

Here are the standout performers of this test, in my personal order of preference. (You can also click here to download the full resolution files.)

Elysia Alpha Master (A1)
This one sounded stiffer and more high-fi than the others—though not by a lot. Since I’m only compressing slightly, it was more about the clean signal path than the sound of the gain reduction circuit. The mix seemed slightly clearer with this compressor, which allowed me to hear more detail within the stereo image, specifically on the percussion.

Shadow Hills Mastering Compressor (A2)
This compressor seemed a bit thicker and slightly more forward-sounding. This could be attributed to the output transformer I selected (“Iron”) and the fact that there are actually two compressors running in series here. Even though neither gain reduction meter was moving much, the mild compression was still pushing things together nicely.

Manley Variable Mu Compressor (A3)
This one sat somewhere between the previous two, with a slightly creamier sound and a smoothness to the high end compared to the Alpha Master; but it was perhaps a bit less thick than the Shadow Hills. It had a nice “glue” to it as well, which is probably attributed to the numerous tubes in the signal path it recreates to convincingly.

Kotelnikov Mastering Compressor (A4)
This was the most transparent of them all, seeming not to add any color to the mix, while lightly touching the loudest hits. Because there is both a “peak crest” and a “soft knee” adjustment, it was quite easy to optimize it for a kind of dual operation. Without the gain reduction meter, I’m not sure that I would have noticed it working at all.

[If you want to go deeper and hear the runners-up in this category, you can download them here.]

Test B: Heavier Song But Light Compression

This test was probably more indicative of how I would go about processing something that is hard-hitting and aggressive. While the compression can help add some color to the tone of the mix and keep things “glued”, I’m still just looking for a little bit of general level control and averaging. In other words, this is not overly-squeezed at all.

In these samples, the compressors were each applying about 1-2dB of gain reduction most of the time. To my ear, this is a fair amount of compression and is quite noticeable compared to the un-compressed mix. Even still, I set them up to add something musically beneficial, and in all instances, the compressed mix was subjectively better than the unprocessed mix.

The song for this sample is from a band called New Language. I mixed and mastered the record Come Alive for them late last year. This song is the title track from that record and is heavily guitar-driven rock with big drums and bass to go along with it. You can hear more of their music and download the record for free by going to their website: newlanguageband.com

Here are the standouts again, presented in my order of personal preference. (You can also click here to download the full resolution files.)

Universal Audio Fairchild 670 (B1)
The Fairchild 670 really seemed to help this mix “come alive” (pun intended) by accentuating the aggressiveness of the band and their playing.

Instead of compressing more by lowering the threshold, I drove the input of the Fairchild slightly harder for some slight rounding of the transients, while still keeping them mostly intact.

The hint of added distortion that this technique gives the track made it sound more intense and muscular. This one felt “loud” regardless of how loud I was actually listening.

Brainworx Vertigo VSC-2 (B2)
The VSC-2 was brighter than the Fairchild and somewhat cleaner as well. It seemed to accentuate the kick and snare transients nicely.

Some of this can be attributed to the availability of a slower attack time than the Fairchild has, but is also due to the sound of the VCA gain reduction circuit.

Instead of pushing everything together the way the Fairchild did, it spread things out nicely making the mix seem wider and clearer. This has the hallmarks of what most people love about the SSL buss compressor, albeit in a much cleaner, more hi-fi way.

Manley Variable Mu Compressor (B3)
The Manley shows up again…not surprisingly. This one made the mix a little bit smoother but also kept the thickness that the Fairchild added so easily.

Using the slowest attack time available kept the transients intact while the slight drive on the tubes made it fuller and polished sounding. Using the sidechain filter also helped keep the big hits “big”.

Klanghelm MJUC (B4)
This one is the most colored sounding compressor of the bunch by a long shot, but it adds some low end girth that is remarkable. I used it in “Mk 2” mode, which is a model of the UREI 176. It made everything seem bigger and deeper even while only gently compressing things.

I don’t really trust the gain reduction meter because it wasn’t moving, but there was definitely some compression being applied. No matter; it really added something that I don’t even think could be achieved if you paired a compressor with a good EQ. There’s nothing transparent about this compressor, but when it’s right, it’s hard to beat.

[If you want to hear the runners-up in this category, you can download them here.]

Test C: Heavier Song With Aggressive Compression

For this third and final test, I went much further into the compressors and made them work a little bit. I think there are enough people that work this way and are looking for compressors that work well with that approach, so I set the compressors accordingly.

For the most part, I went with medium to slow attack times and medium release times; unless there was an auto release function, which I opted for instead. I also set the ratios a bit higher at 4:1 instead of the moderate 2:1 ratio as I had used before.

With high-density, hard-hitting tracks, the compression can be noticeable—and not always desirably so—so getting the release right was paramount. Oftentimes the auto release function allowed me to keep compressing 3-5dB without audible pumping or breathing.

(Since this mix was already done, I was unable to manipulate the mix to accommodate some of the compression changes. Were I mixing the song while applying compression, I could use more athletic automation moves to make things behave more predictably.)

For this test I used a song from a band from Germany called Nissefort for whom I mixed their upcoming record. The song is called “Alone” and will be available when they release the record sometime in 2017. You can go to their Facebook page to connect with them: https://www.facebook.com/Nissefort/

This song is also aggressive with tons of guitar, bass and drums, all fighting for space with the vocal. I thought that this type of song was more suited to be compressed more, without suffering some of the pitfalls of over-compression that occur on more dynamic songs.

Once again, in my own order of preference. (And you can click here to download the full resolution files.):

Brainworx Vertigo VSC-2 (C1)
Once again the VSC-2 works well on loud, aggressive music. It does some cool and noticeable things to the sound of the drum transients and seems to pull the guitars a bit forward while smoothing them out. It doesn’t appreciably soften the sound of anything either.

While I can clearly hear it working, it does add a cool sense of movement and excitement that really works on a track like this one. The use of the auto release function allows the compressor to be more agile in following the changing dynamics in the louder section.

Slate Digital-FG Grey (C2)
It’s no surprise that another SSL buss compressor was close behind the Vertigo. These sound pretty similar, though the Slate is not quite as open sounding on the top end. I also found that the Slate seemed better if I drove it a little further into compression than the Vertigo. Once again, I used the auto release function and this one felt pretty full and in-your-face.

Klanghelm MJUC Mk3 (C3)
This is technically a Variable Mu type compressor but it has characteristics that seem more like the SSL comp than the other vari-mu models in this compressor. Once again, it added a ton of low end thickness which made the track have an air of authority and power.

Chandler Limited Zener Limiter (C4)
This limiter sounded cool, but it took a bit more manipulation of the track to make it do what I wanted. The Zener Limiter has an unusual gain structure, and when compressing complex material like a full-on rock mix, it’s not always easy to keep it out of compression without turning something down in front of the limiter. Additionally, it’s not always easy to make up the lost gain after you trim it back to get the compressor to behave as you want. It’s a very aggressive and colored sounding compressor, so when it kicks in, it’s not subtle!

In order to get it inline with the other tracks and to make the compression work the way I needed it to, I had to turn down the front end of the track so it still hit hard on the loud part (see image 13). This is not a big deal when you’re mixing because you can account for this, but in this instance it was worth noting what needed to happen to make a true “apples to apples” comparison.

Despite all of that, the compression sounded so cool when the track got loud that I felt it had to be included. It’s not transparent or subtle but it does have a ton of character that many may find appealing.

[Once again, if you want to go deeper and hear the runners-up in this category, you can download them here. To see the exact settings used in any of these tests, click here.]

A Few Observations

Whenever I write an article or do a review of something, my main goal is to offer you, the reader, some perspective and information that you may not be able to find anywhere else. At the same time, I also hope that my own perspective will be given a shakeup that will force me to reexamine what I do and how I do it, so I can improve the quality of my work.

When it comes to 2-mix compressors, I have always been a bit old school, meaning that the compressor is there to enhance the sound of the mix but is not the thing that the mix lives or dies by. In the last 10-15 years however (and in some cases earlier) the 2-mix compressor has become elemental to the work of so many top-flight mixers that it was worth exploring what a more heavy-handed approach can bring to a mix. I can’t say that I would necessarily change the way I go about compressing the mix all the time, but I do see the appeal of the sound that it can create.

This experiment also made me realize that it would take a change in my mixing process if I chose to adopt a more aggressive style of compression on the 2-mix.

When I’m mixing, I work on my different instruments (drums, bass, guitars, keys, vocals, etc.), and then I work on the balance between them. After that, I work on different sections from loud to quiet to make the balances work, and to make sure that the transitions are smooth and musical.

Once that’s sorted out, I work to make certain that the static mix (before automation) is solid and works well without much further manipulation. Once everything has been accounted for, then I insert the 2-mix compressor on the stereo buss. At this point it is simply adding glue and enhancing the tone. I will then follow with automation to make the mix interesting and to make the compression work even better while accounting for the changes that the compressor may have caused.

By contrast, when I’ve worked with people who use a stereo bus compressor more aggressively, they tend to start the mix with the compressor inline. This way, every decision they make directly affects what happens when it hits the compressor, and they build the mix to deal with that.

On one hand it seems backwards to fight something from the beginning. But on the other hand, if you prefer the sound you can ultimately achieve by using more aggressive bus compression, then why not leave it in and deal with the issues that arise, as they arise? That way, you can hear the way the compressor reacts to your changes in real times, and adjust accordingly.

There is no “one way” to mix, that’s for sure. If you give 10 mixers the same tracks you will get 10 completely different mixes. But acknowledging that you probably have a specific way of doing things may cause you to change it up a bit and see if a new approach is better…or just different. I hope that some of these observations will inspire you to take a step back from how you mix and see if a different approach can jump-start your mixes.

Mike Major is a Mixer/Producer/Recording and Mastering engineer from Dunedin, FL.

He has worked with At The Drive-In, Coheed and Cambria, Sparta, Gone is Gone, As Tall as Lions, and hundreds of other artists over the last 30 years.

Major is the author of the book Recording Drums: The Complete Guide . Try his new premium course, Mixing Drums: The Method to the Mix. Try it today at MixingDrums.com.

For more great insights into both mixing and mastering, try our full-length courses with SonicScoop editor Justin Colletti, Mixing Breakthroughs and Mastering Demystified.

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