Audified U73b Rare Vintage Compressor Plug-In

Definitely not your typical compressor…

By Craig Anderton

One of the great aspects of writing software reviews these days is downloadable demos, because you don’t have to depend on a reviewer’s opinion—you can decide for yourself whether you like something or not. But first, you have to determine if you want to take the time to download and learn how to use something well enough to evaluate it, which means reviews still have value for “filtering.”

That’s particularly important with the U73b, which is one of the more unusual compressors to visit my hard drive and at $149, also one of the more expensive ones. It emulates an all-tube, German broadcast compressor/limiter that’s around for around half a century. Fortunately, I have three of the original units here so it was easy to compare and contrast...well, not really. Actually I’d never even heard of the U73b before finding out about this plug-in, so there’s no way I can judge how accurately the software emulates the hardware. However, I think it’s more important to evaluate what the U73b can do for your music, regardless of its heritage.

Installation is straightforward, but note that it uses iLok protection. The U73b supports AAX, RTAS, VST3, and VST2 formats on Mac and Windows, as well as AudioUnits on the Mac. Compatible operating systems are OS X 10.8 and above, and Windows Vista and above (32 or 64 bits).

Controls

The control set is minimal. A 3-position switch chooses compression, bypass, or limiting. Like the 1176 and many other vintage compressors, turning up the Input control increases the amount of compression while an Output control tames the overall level. A six-position release control offers three fixed release times (0.3, 0.6, and 1.2 seconds) and three long, program-dependent release times (2.5, 6 and 10 seconds). Also, stereo sidechaining is available where you can choose to control both U73b channels independently, by the sum of the two sidechain inputs, or by either the left or right channel.

The original circuit included a highpass filter, but thankfully the software version allows turning this off (it’s always off when limiting). The meter can read input, output, or amount of gain reduction. That’s pretty much it, except for the crucially important “calibration” control. This matches the unit to the signal levels you use. For example, if you leave a nominal 6 dB or headroom, you’d set it for -6 dB. Overall range is from -18 dBFS to 0 dBFS. Without setting the calibration control properly, the artist presets (including contributions from Bjorn Thorstrud, who’s worked with the Smashing Pumpkins, Marianne Faithfull, David Coverdale, Whitesnake, Shania Twain, and others) won’t reflect what the U73b can do.

In Use

When people think of “character” compressors (e.g., something like an Omnipressor), the usual assumption is that the audible result is going to be heavy-handed and obvious. While you can abuse the U73b to squash signals, that’s a waste of a plug-in that’s capable of very refined compression and to a lesser extent, limiting.

The U73b does not have a “maximizing” or peak limiting character. It is very much an “old school” compressor that seems more interested in bringing up low-level signals than squashing high-level ones. For example, with drums and voice, it can bring up room ambience very effectively while keeping voice at a consistent level. Drums are a somewhat different story, as the attack time is fixed and extremely fast—a little less than a millisecond. That takes away a lot of the percussive nature of the drums if you’re using significant amounts of compression, however the U73b is absolutely wonderful for parallel compression by virtue of how it adds detail to the drum sound. On bass, the U73b effortlessly brings up lower-level sounds, like notes that weren’t hit quite so hard, or “dead spots” on the neck.

Although the original hardware unit was used quite a bit for mastering, don’t expect a multiband maximizer. If the compression is audible, to my ears it detracts from the stereo mix. What the U73b does best is provide a “lift” that also glues tracks together effectively. (If you want to get more level to be competitive in the loudness wars, follow it with a limiter or maximizer.)

Interestingly, in all these cases the sound doesn’t have the subtly “muffled” quality you sometimes hear with compressors; instead the vibe is quite detailed and articulated. It sounds like perhaps the highs are not being compressed quite as much as lower frequencies, but I have no way to confirm that and something else might account for what I’m hearing.

The Catch

So far you’re probably thinking “Hey, this sounds pretty cool…I’m going to download the demo and check it out!” However, obtaining the sonic nirvana the U73b can deliver is not always easy. While it may seem that setting controls would be simple, the interaction between Input, Output, and Calibration means you’ll need to spend some time getting the right settings. The Calibration control is particularly important for natural sounds, although the flip side is that if you want seriously squashed effects, a “wrong” calibration setting will get you there in seconds. In fact given my emphasis on subtlety and clarity, I should point out it’s not hard to abuse the U73b. But also be beware that it’s easy to abuse the U73b if you don’t treat the Input, Output, and Calibration controls as a “combination lock” where they all have to be set correctly for the best results.

I also have two issues. The first is that the controls do not allow for linear mouse manipulation over the full travel, you need to “rotate” them. With plug-ins that have the option to do knob rotation or linear motion, the first thing I do is set preferences so I can just drag up and down with the mouse. I realize it’s more “authentic” this way, but I feel it unnecessarily complicates the process of getting the levels just right.

The second issue is that the unit defaults to the high pass filter being enabled for the compressor. This replicates the way the original worked, and it’s great that Audified includes a way to bypass it—something the original couldn’t do. However, I believe making it the default is a mistake. I can see someone not bothering to read the help, loading the plug-in, and thinking “Hey! What happened to the bass?!?” I would recommend that Audfied disable the HPF as the default to give a good first impression to people who don’t have the patience to read through the concise help info.

Conclusions

The Audified name may be new to some people, but the company’s lineage traces back to the 90s and DSound (which made high-quality “stomp box” plug-ins at a time when the concept was still pretty new) as well as the Audiffex name, which is associated with affordable music products. (One of these, a live performance program that’s kind of like a more developed version of Mainstage will be the subject of a future review.) They also made some of the first OS X plug-ins, as well as plug-ins for TC’s PowerCore. So there’s a considerable amount of expertise to back up the company’s claim that the U73b is a faithful emulation of the original.

Ultimately, though, what matters is the functionality. I have to admit I was skeptical when Audified asked if we’d review the U73b…“oh no, not another compressor!” However, after working with it on individual tracks and program material, I have to say it is not like other compressors. The closest I can come with my existing roster of dynamics processors is by using two compressors set for light compression ratios in series, but it’s still not quite the same.

The U73b can offer subtle, non-intrusive compression that gives a welcome “lift” to signals. I haven’t talked much about the limiter because for me, it’s more like an alternate sound that can indeed be useful, but is not particularly flexible compared to dedicated limiter plug-ins. The main attraction here is the compressor, and it’s both well-behaved and capable of enhancing just about anything you put through it once you get the control settings squared away. Props to Audified for not making “just another compressor” but offering something sophisticated—and unique—in dynamics control.

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 Craig Anderton is Editorial Director of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.