The Great Mix Bus Compressor Plugin Shootout: Which One is Best for Your Stereo Bus?

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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.

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  • George Piazza

    I have most of these compressors in my arsenal (Manley, Vertigo, Alpha, Fairchild, Shadow Hills, Kotelinkov), and a few others that I think are nice.
    I’ve had somewhat similar experiences with Mike Major, with slight exceptions.
    The Manley is nice for less aggressive music. It doesn’t always provide the thickness one might want with heavy rock mixes (though it can be a great group buss compressor before the main compressor). The tube sheen is excellent, complimenting the high end nicely. In 1:5 mode, it is really designed to be hit rather hard, as the compressor gives up after @ 10 dB, which lets drum transient through while retaining thickness.
    The Shadow Hills either works or it doesn’t. I think the mix has a lot to do with this, especially given the two compressors in this beasty (though you can use only one if you want). It also often makes a great group compressor, especially in situations where the transformer selection adds to the sound – like acoustic & electric guitars, bass, etc.).
    I almost never use the Fairchild as a mix bus compressor; it’s fast attack time and heavy coloration rarely works for any of my mixes. It is occasionally the perfect track or group buss compressor though.
    The Slate lineup is odd. Every now & then one of them works (usually the Grey – SSL or the Red – Focusrite); the mix knob can really help retain some of the ‘clean’ sound, though I’ve noticed phasing problems with earlier versions (Slate may have fixed this by now). I do not find the distortion on the Mu very convincing; it sounds a little cheap to me.
    The Elysia Alpha Compressor is a kind of ‘desert island’ choice for me. It is so flexible, it can deal with numerous needs, especially with it’s feedback / feed forward selection, auto attack & auto release, mix feature and mid-side mode. Not a lot of coloration per se (unless you use the peak limiter function), but for thickening up & widening, it does the job.
    The Vertigo is very nice; the gain knob adds a subtle grit; it has all the settings of an SSL, but sound better than wither the UAD or Wave SSL Buss Compressor. It is not always the right tool for the job, but it is right there with the Alpha & Manley. The auto release is excellent. I could live with these three if necessary.
    I have also successfully used the UAD Neve 33609, the PSP MasterComp and/or Vintage Warmer, the Voxengo Polysquasher and the Sonnox Compressor (+ gate / expander / warmth / sidechain).
    The free guy – Kotelnikov – is very clean & flexible; well worth the download.
    Izotope’s Ozone has improved over the years, but it is a bit of a beast to deal with; besides, multiband is not the topic here.
    My favorite secret weapon for the main buss is the DGM Essence. It is not only an excellent mastering De-Esser; it also does various parallel compression tasks better than anything else I have tried. I can always dig out 2 – 5 more dB with a mix and still sound transparent with it. It includes excellent presets by Bob Katz for various parallel compression needs, including bass, mid or treble thickening (tonal parallel compression) and an excellent starting point for the transparent parallel job. A real hidden gem!

  • Justin C.

    Thanks for sharing this take George! Glad to have read it. I’ll have to check out the DGM Essence. Not too familiar with it yet myself.

  • Mike Major

    I’ve never tried the DGM. Now you’ve piqued my interest, damn it…

    You’re not helping!

  • Eddie TX

    Great work putting this shootout together! Thank you for doing it.

    Was wondering if you’ve tried the new API 2500 from UAD (I assume you’ve tried the Waves version) — it’s really something.

    Also, there are very interesting things coming out of Acustica Audio (of Nebula fame) lately. Their Coral, Lime, and Sand compressors are among the most hardware-like plugins I’ve ever used. If you can figure out their demo procedure, they’re well worth checking out.

  • jes

    This was a great article, thank you!
    I use mostly UA (I mean a *lot* of UA, and almost always in Pro Tools, FWIW) and seem to change up that 2-bus compression almost per project, but I have to say I do like the Shadow Hills. In your example A test, one thing I also hear also is more of the ambience in A2 with the Shadow Hills that I don’t hear in the others.

  • Mike Major

    Thanks Eddie! Glad you liked the article. It was quite a bit of work to put it together but I learned a few things along the way, which I didn’t expect.

    I have tried the UAD API 2500. I was going to include it in the shootout but just couldn’t make it do anything that I liked, so I left it out. I had so many others to choose from (probably too many) that I felt it wasn’t necessary to include. Now having said that, it may work well for some folks and I know that some engineers love it and swear by it. Just not my taste, I guess.

    I haven’t seen the Acustica stuff yet, so I guess I have to go check that out now.

  • Mike Major

    Thanks Jes! Glad you liked it.

    The ambience difference you hear probably has to do with the interaction between release times of the optical comp and the VCA comp. Since they’re different and the gain reduction circuits respond differently to the transients, it must have seemingly extended the decay of a reverb and brought it forward, thus making it more apparent. At least, that’s what I think is happening…

    I probably use the Shadow Hills more than anything, even with all of the choices I have. The combination of the two comps in series is pretty powerful and usually transparent. Plus, being able to change the output transformer can really affect the tone of the whole mix positively. Sometimes it just doesn’t do the trick, so I look elsewhere, but more often than not it works perfectly.

    I find that the choices available are more fully exercised when I’m mastering because the different comps offer more tools with which to shape things. When I’m mixing or mastering my own stuff I don’t need as much variety because I have a way of putting the mix together that is well planned before I ever insert the two mix comp; in other words, it doesn’t make as big a difference overall for me personally. But now and then, something weird ends up on the 2-mix!

  • Eddie TX

    Cool, Mike. Thanks for the reply. Yes, the API doesn’t work on everything, but when it does …

    Acustica has some unique tech and it’s finally coming to fruition in the form of usable plugins. They do have some work to do on the whole customer experience — it’s a pain just to download and authorize a demo — but wow, the sound. Hit me up if you have any questions about getting set up with those. Thanks again for the shootout!

  • Mike Major

    Yeah, the API was a head-scratcher for me, honestly. I have tried it a dozen times and can’t ever get to the point that I’m like “OK! That’s it!”. I know some people love it.

    Since you posted this I looked at the Acustica stuff and it looks really intriguing. Lots of cool things that appear to be based in reality but with a twist. I will be trying the some demos here soon. Thanks for the tip!

  • Adrian

    These differences are incredibly marginal. Not worth the headache.

  • Mike Major

    Hi Adrian. Are you listening on a good set of monitors or high quality headphones? The differences are pretty significant in some of the samples. I agree that when they’re not driven too hard they are more similar, but the differences in tone and dynamics control should be noticeable.

  • denis la malice

    I must say this like this : this shoutout makes very little sense since the way you mix one song will be influences by the comp you will use as 2buss, so it is much more like some mastering comp shoutout and even that is flawed since some will react better one one type of mix than one other.

    Experience with working with one typical pluggin will dictate your choice, not a shoutout.

    Personal taste also : for instance, I’m not big with the vari-mu as buss compressor, I doubt I would chose the pluggin for that matter, I base this choice on many attempts.

    I always used the SSL buss (not big with any pluggin versions) and loved it : but it is not a transparent one at all, so it might have sounded terrible in this shoutout, but have you “mixed” the track in it at the beguining of your test, it might have ended with the best results.

  • denis la malice

    Now that said, out of experience (not this shoutout), I like the Shadow Hill quite a bit. 🙂

  • Greg Strickland

    Perhaps no mix buss compression is best. Particularly for a radio mix or any mix likely to receive audio processing downstream. Should you presume your mix sound is the sound heard by the entire audience?

  • Mike Major

    Sometimes that’s true, but I like what a comp does to the sound of the mix. I am always cognizant of how things will inevitably change downstream (mastering, radio, iTunes, etc.) and try to mix in a way that minimizes the differences between all of the delivery media. But ultimately, I just like how using a comp makes things feel more together and complete. Also, if I control the way the dynamics are presented then I’m less likely to be surprised by how some downstream process affects them. I can remember some stuff I mixed way back when that really sounded strange on the radio. There’s ways to fix that and compression is one of them.

  • Mike Major

    Well, honestly, the whole purpose of a shootout is to directly compare the way the different options perform under the same conditions. Otherwise there’s no reference point. Without a reference point then it’s not an apples to apples comparison.

    If I stand in front of a mirror and try on 5 shirts then I know exactly what those shirts look like on me at that point and in that lighting. Knowing this I can then decide which one I would wear to go the movies, which one would be best for a job interview, which one makes me look fat, etc.

    Likewise, I can compare how each of these comps react to the same music, with basically the same settings, and then extrapolate how that would work in other situations that I may need to use a compressor. It’s like any audio gear that we ever hear: you listen, make a judgment and then file it away in the memory banks for later recall: “that would work great on this type of mix”, or something like that.

    Not everyone has experience with all of these compressors, so I am offering a direct comparison under specific conditions so they can hear what is different and what is the same, that’s all. It’s somewhat subjective because I had to set the compressors, but I also tried to be as scientific about the process as I was able to do and still fulfill the goal of the shootout-which is to show how a bunch of different compressors sound on a mix.

    And trying to mix a song for each compressor would have taken a month and would tell the reader nothing useful except that I could use a different compressor on a bunch of different mixes. That’s not illustrative in any way.

  • denis la malice

    I agree with you mostly. I just wanted to point the limitations of this particular shoutout . best regards

  • Ray Tubes

    I like the Alpha’s transient punch.
    The kick is tight, solid, while retaining good bottom end and the guitars are nice and spanky.
    The image is quite wide, and it is interesting how the triangle is much more forward than the Shadow Hills.

    Shadow Hills has a nice overall balance, sounds a bit wider than the Alpha, good transient response though less in your face feeling.
    I suspect this is the Steel trafo setting as opposed to the Nickel and feel the Nickel would sound more forward.

    As for folks not mixing into a 2 Bus comp, many of is do even if the mix goes out uncompressed.

    The balance of the mix and EQ tends to be different when mixing into compression and this can be a great way to have a more polished mix for your mastering engineer to work with.

  • WayneD

    Brilliant thanks so much for getting this together esp supplying files. Very helpful.

  • Null Static Void

    Guess I’m a little late to the party.
    Surprised you skipped over the other UAD offerings. I’ve used their 1176 and LA2A plugins for 2 buss for years. The 1176 is tricky, but it sounds right on certain mixes.
    The Neve 33069 though seems perfect for the job. It can do overdriven, or clean and is quite adept at making just about anything sound 110% thicker.

    I could name a bunch of other UAD plugins, and that is kind of the thing. You could easily write a whole article on just UAD 2 buss plugins.

    btw, I always throw an EQ on there too.

  • Steven Adams

    sknote’s SDC is a fantastic emulation of the Shadow Hills!

  • Marcus Mittilä

    This was a great read, interesting comparisons! Thank you!