PAR Picks 6: Software Bus Compressors

Our software editor shares a half-dozen of his favorite mix bus compressors.
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Our software editor shares a half-dozen of his favorite mix bus compressors.

Compression is one of those things that can either glue your mix together perfectly or squash it to oblivion. Of course, different compressors react differently to the material fed into them; an edgy rock tune requires something different than a soft classical piece. Like different spices in a chef's kitchen, compression, if needed at all, is added "to taste." Here, I share six software compressors that I have found deliver excellent results when strapped across a mix bus.

Waves API 2500 Compressor

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1 Waves API 2500 Compressor
This stereo compressor for TDM, RTAS, Audio Suite, VST and AU is my go-to compressor for anything with big drums and guitars. It has that beefy, classic API sound and can be driven hard. The most creative controls are found in the Tone section, where you have Threshold (Knee Hard, Medium, Soft), Detector (Thrust Loud, Medium, Normal) and Tone Type (New: Feed Forward, Old: Feed-Backward).

Of course, there are the standard Threshold, Attack, Ratio and Release (with five fixed settings and one variable setting). It has dual VU style meters up top and can be used as a linked stereo unit or two separate mono channels via single compression setting. The Analog button can turn the internal analog modeling on and off (I always leave it on).

For rocking music, nice results are delivered by setting the Knee to Med, Thrust to Med, Type to Old (Feed Backward), the Ratio to 1.5 (lowest setting) and a fairly quick attack and release. Then add some makeup gain and hit the bypass button. It makes things sound just like the old Who record, Meaty Beaty Big and Bouncy. Case closed!

Prices: $400 (TDM or Native)
Contact: Waves |

Massey Plugins CT4 Compressor

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2 Massey Plugins CT4 Compressor
It doesn't get any simpler than this: Compression and Makeup knobs, fast and slow switches for Attack and Release and an analog-style dB meter. When used on a bus mix, I find both the Attack and Release work best on fast settings.

The predetermined compression curve is fixed at soft knee with a peak ratio of about 5:1. According to the website, the "compression knob acts like a threshold and ratio control rolled into one — turning it up simultaneously lowers the threshold and increases the ratio."

The CT4 is great for removing the "edge" from mixes, and I feel it shines on acoustic music pieces, although it works on most anything. To me, it doesn't add any particular sonic character; it just makes things sound a little better with a few knob twists. The CT4 will run with RTAS, TDM and Audio Suite formats.

Price: $69 direct
Contact: Massey Plugins |

Sonnox Oxford Dynamics

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3 Sonnox Oxford Dynamics
Oxford Dynamics for TDM, RTAS, Audio Units, VST and PowerCore systems is a bit more than just a standard compressor. Aside from the usual features, it adds Gate, Expander, Limiter, SideChain EQ and Warmth. I do occasionally use the EQ and Warmth sections to add a touch of high-end sparkle and bottom to mixes. But for me, the added features apply more to its use on individual tracks.

When strapping it across a bus mix, I focus almost solely on the Compression section. You can start by choosing three different types of compression: Linear, Normal and Classic. They each have a slightly different sound with which you need to experiment to find what works best for your needs. Classic reminds me of old dbx-style compression, offering nothing except Threshold, Ratio and Make Up gain. Normal and Linear mode offer the above features as well as Attack, Hold and Release.

Additional useful features for use on a stereo bus include a Dither feature (24- and 16-bit) and Variable Soft Knee (0-30 dB in 5 dB increments), which provides a real soft touch. I call the Oxford my invisible compressor, using it to tighten up a mix without hearing any obvious compression artifacts. It creates the feeling that all dynamics are retained without any negative effects and delivers very clean results.

Prices: $200, $350 and $495 (Native, PowerCore including Native and HD including Native, respectively)
Contact: Sonnox |

URS 1970 Classic Console Compressor

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4 URS 1970 Classic Console Compressor
The URS 1970 is another easy-to-use, good-sounding, bus compressor. On the Compressor-only version, it offers controls for Input Level, Gain Makeup, Compress Ratio, Compress Threshold, Attack, Release and a Compressor "In" button. You also have I/O metering and an analogstyle Gain Reduction meter.

It provides "digital recreation of transformer input and diode bridge gain reduction amplifier characteristics," as URS documentation explains. To me, it looks like a module out of an old Neve, and sonically, it delivers that Neve character when strapped across a mix.

I simply call up the "Mix Bus 1 Easy" preset and start tweaking from there. It features high-res, 48-bit, double-precision processing on the TDM version and high-res, 64-bit, double-precision processing on the Native version. Note that it will also work with AU and VST systems. The 1970 is a nice, simple compressor that works with a lot of different kinds of material.

Price: $199 and $99 direct (TDM/RTAS/AU/VST and Native/RTAS/AU/VST versions, respectively)
Contact: Unique Recording Software (URS) |

Eventide Ultra-Channel featuring Omnipressor

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5 Eventide Ultra-Channel featuring Omnipressor
This one is actually a channel strip packaged with the Eventide Anthology II Plug-in Suite (TDM), but has some great stereo bus applications. I find it the most aggressive of the bunch in this PAR Picks 6 installment, due primarily to the inclusion of the truly unique Omnipressor.

For those of you who haven't tried the Omnipressor, there is nothing else quite like it. The original unit can be a frustrating thing to dial in, but when you get it right, it's amazing. Luckily, with the Ultra Channel, its been made simple with Threshold, Ratio, Attack, Release and Gain.

For bus applications, I don't use the Gate, De-Esser, Stereo Delays or Harmonizer. I craft the sound using the Compressor/ Limiter, five band EQ and Omnipressor. On mixes with a lot of vocals, I tend to hit the Compressor section very lightly, if at all. I'll then adjust the Threshold on the Omnipressor so the needle bounces just a bit, and add a few dB of make-up gain. Often, I'll also pull out a touch of lows in the 120 Hz area, just to keep things clean. To check results, I'll simply pop each section in and out using the I/O buttons. The Ultra Channel can do both light and aggressive bus compression.

Price: $1,195 list (as part of Anthology II Plug-in Suite, Mac or PC for TDM)
Contact: Eventide |

Universal Audio SSL G Series Bus Compressor

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6 Universal Audio SSL G Series Bus Compressor
UA touts this plug-in for UAD-2 cards as "a faithful, fully authenticated, circuit emulation of the legendary SSL 4000 G console's bus compressor." 'Nuff said. When first trying it out, I immediately strapped it across a Pro Tools master fader on a music mix, called up the "Buss Smooth" preset, and had an authentic "Oh, yeah" moment. It can best be described as cleanly punching the mix up without really hearing blatant compression, even though the needle is obviously moving.

It's easy to use. The only features are an analog meter, Threshold, Attack, Ratio, Make Up (gain), Release and the In (bypass) button. The compression ratios are fixed at 2:1, 4:1 and 10:1, it has up to +15 dBu of makeup gain, and the Compression VU Meter will read from 0 to 20 dB. It also has the original Auto Fade feature (1-60) seconds as found on the original console. I never used it then, and I still don't use it now...but it's there!

The SSL G Series Bus Compressor definitely rips when used on the master fader. Like a good compressor should, it helps glue mixes together and literally lifts them out of the speakers. The only bummer is you do need a UAD-2 card to run it.

Price: $249
Contact: Universal Audio |