Looptrotter: Emperor 500 Series Limiter

A few months ago, I was lucky enough to travel to Copenhagen to record an LP for the awesome band Town Portal. It was easily the best audio experience of my life, and, as a bonus, our basic tracks sounded fantastic. When I sat down at home to mix, all I wanted to do was "big" things up a bit. Parallel compression seemed like a good way to increase the drums' density and size without taking away any transient snap or messing up my mix. So, once I got the mix going, I took a quick detour to audition two or three parallel drum chains. This turned into a few hours of printing more chains to compare, then turned into me borrowing gear from the studio next door to print a few more, then turned into me sending those tests to two friends who ran my drums through a dozen more setups, and sent files back. This was ridiculous, yes, but super educational. One takeaway was that you can't always predict how a parallel chain will sound combined with the original signal, and in fact lots of stuff that sounded cool on its own didn't work so well blended.

Okay, set all that aside for a bit. Looptrotter Audio Engineering is a cool Polish company that's been on my radar for a year. They make a handful of novel compressors and saturators - all very bright yellow. The Emperor is an aggressive, fast FET limiter with only a few controls; an Input level knob, Sidechain low-pass and high-pass buttons, plus a button that toggles between Fast, Med, and Slow speeds. That's it! There's a 2 rack space version with big VU meters and stereo linking, and also a 500 Series version with LED metering and no linking. I reviewed a pair of the 500 Series units.

The Emperor's three compression controls only take a few minutes to understand, but they combine to offer a lot of options. The Input knob causes more compression and saturation. The speed buttons change both attack and release times: Fast swallows transients and rebounds immediately, Med feels like a middle-ground Universal Audio 1176-style setting, and Slow lets lots of transient through while pumping a bit as it recovers. The sidechain buttons change the signal that the compressor's detector circuit hears: one reduces low frequencies, and the other increases high frequencies. You don't hear these filters directly - they're only used by the compressor's detection circuit - but they can really change the compression character, particularly on an aggressive compressor like this.

There are three other controls on the front panel that I haven't mentioned: a bypass button (labeled Process) plus Wet and Dry output knobs. Unlike some other units, Bypass really means bypass - the level controls aren't active, so it's easy to match level between your original signal and the processed one. I find this really important when auditioning compressors and EQs, otherwise it's too easy to prefer whichever signal is louder. Separate Wet/Dry knobs make it fast and easy to try different parallel ratios, or to listen to only the wet signal while you're fine-tuning sounds. Which finally brings us back to my extended introduction: parallel signals often sound pretty different on their own than when blended in. With the Emperor it's easy to think about both at once. In my testing I came back to this over and over again.

Sonically I like the Emperor a lot, and its controls are immediate and gratifying. An obvious use for a compressor like this is for kick and snare drums. You can do "turbo" parallel processing in one unit, smacking and shaping attacks then blending for aggressive attack. You can high-pass the sidechain on a kick drum to let the attack drive the compressor rather than all the low end energy. The Slow setting lets a lot of transient pop through but levels out hits and brings up sustain. When used gently it makes kick drums bigger and more even, plus does a nice thing to snares too - a different shape than a Universal Audio 1176 or an Empirical Labs EL8 Distressor [Tape Op #32] at a 4:1 ratio. If you set the Emperor's speed to Fast while driving the input hard, you can blend just a little wet signal in for giant kick drums, snares, and toms. I also compared the Emperor to one of my favorite compressors for kick and snare drum, the Tonelux TX5C - another 500 Series compressor with a tilt-able sidechain and wet/dry blend. The Tonelux is bright and creates a distinctive "pop" while the Looptrotter is tonally darker and less snappy - offering a unique character of its own.

Strapped across an entire drum bus, it's easy to dramatically change drum sounds. The low shelf button keeps the kick drum from creating pumpy over-compression; Slow mode lets lots of drum attack through and provides movement that works on its own or blends well in parallel; Fast mode crushes drums and sounds cool in parallel. On vocals, the Emperor's distortion character is flattering, and again, a lot of gain with Fast mode blended to taste will thicken and even out vocals so there's less word-by-word fader riding needed, but with far fewer weird artifacts on hard glottal sounds. For vocals I liked both sidechain buttons engaged - the low shelf kept plosives from triggering weird compression, and the high shelf provided useful sibilance ducking. (That's pretty much how de-essers work).

I like LED meters on fast compressors like this - not unlike a Distressor or an FMR Audio RNC 1773 [#13]. But when you're using the Emperor for saturation it's easy to let the meter make you feel bad about how hard you're driving the input levels. Whatever! Crush! By the way, the RNC has a digital sidechain, and the Distressor has an analog sidechain with digitally controlled functionality. The Emperor feels similar but Looptrotter tells me the sidechain is all analog. There is a tiny Arduino chip on the PCB; the front panel controls are digital and the Arduino brokers settings between the panel and the analog circuit. This is arguably good for recall and unit-to-unit consistency.

I have a few minor gripes. Like every 500 Series unit, the little knobs are little. So, they're hard to match and hard to recall. The little buttons are little too, and they're sensitive so it's easy to press one by brushing against it. And finally, at least one of my units didn't always remember its button settings when it powered up - so keep an eye on that between mix days.

But these are minor complaints. The Emperors are cool. They're a clever, easy to use take on FET compression and color, they ask to be used aggressively, and I don't know of another compressor with this set of controls. Looptrotter's YouTube channel has genuinely useful, hype-free demo videos. Spend some time watching them and you'll get a good idea of what these units do.