Last summer, I invited myself to Panoramic House, John Baccigaluppi's studio in Marin County. I was thinking about buying a new mix-bus compressor, and Panoramic had a few I wanted to audition. Plus, really, I just wanted to see the place. And holy shit, it is glorious! For a crazy low rate, you stay in this sprawling, beautiful house that overlooks the ocean and is furnished with a 32-channel API, plus a sick mic closet and tons of incredible outboard gear. Someday, I will find a way to make a record there. 

Okay, anyway — compressors. I showed up with a half-dozen of my own mixes, printed without any mix-bus processing, and ran them through I don't know how many dollars' worth of compression — Daking, Chandler, Retro Instruments, Thermionic, Old World Audio. After a couple of hours, Scott McChane and I shrugged and agreed: My mixes sounded pretty good on their own. Hah! We never heard some magical improvement that said, "Buy me now. Take out a loan." What an unexpected result! What a relief! 

So I went home and bought a bus compressor anyway — a Foote Control Systems P3EX, which I had never tried or heard before. Gear is weird sometimes. And really, bus compression isn't always something you can slap on and immediately appreciate. The Foote is in fact, a cool, unusual compressor — thick, chewy, colorful, slow — but it's almost the opposite of the SSL- style compressors I have mixed through for years, and I found myself missing the fast, transparent SSL thing, particularly on fast hardcore and metal. 

Which finally brings me to the TK Audio BC501. On paper, the BC501 is literally everything I want from a stereo bus compressor: SSL-inspired VCA circuit; 500-series form factor; stepped controls; adjustable high-pass filter on the sidechain; a blend control for parallel compression; large clear metering; and a "THD" button to add some distortion. That's quite a feature set — deeper than most hardware bus compressors on the market — yet the BC501 sells for $1000. Seems too good to be true — so how does it sound? Fucking great. I don't know what else to say. I installed the BC501 in my 500-series frame, patched it up, loved it — and it's stayed on my mix bus ever since. It is fast and clean, but while it works, it also has a pleasing sonic something that really does it for me. I prefer it to the $2,900 Smart Research C2 — a fantastic compressor — that I've had on loan for months, and I prefer both of those to every plug-in I've tried. 

My typical mix bus setting is 2:1 or 4:1 with a fairly fast attack of 10 ms or 30 ms (though the BC501 can go much faster); a very fast release of 50 ms (the fastest it can do); and threshold set so the BC501's meter shows 2-4 dB of gain reduction on peaks. For some projects, I'll use more aggressive settings, but blend at 50% or so. The built-in Blend control is kind of a game- changer. Patching up parallel compression can be a little tricky on mix bus, and regardless, it's tedious enough that I may not do it just to experiment. Now it's effortless. Similarly, the sidechain HPF is a feature that I wish every bus compressor had. With the music styles I mix, I work hard to avoid pumping artifacts caused by low-frequency energy on kick drums, and a HPF'ed sidechain is the best way to do that. I leave mine set to 150 Hz. 

The broad range of controls means that the BC501 has interesting uses beyond bus compression. For instance, it sounds great crushing room mics at 10:1 with a wicked-fast 0.1 ms attack, and again, you can use the Blend knob to control how much crush you hear. And the BC501 should make a respectable tracking compressor too. Why not? The only limitation is that it doesn't run dual mono, so you only get one compressor out of it, but I'd happily strap one channel of it across a vocal or a bass guitar while tracking. 

The THD function is very mild to my ears. (To be fair, I deal with a lot of very distorted sources.) If you want a bit of hair on your mix, you can use it without worrying that you'll later regret it, but don't expect dramatic changes. 

The BC501 is hand-assembled in Sweden, and build quality is excellent. Its guts look oddly scarce since it's built with tiny surface-mount components, which are slowly obsoleting old-school "through-hole" components (the resistors and capacitors we normally think of). This may make service a little tricky down the road. The controls feel great, and the front panel is well- designed and easy to read. My unit doesn't have numbers on the threshold, make-up, and blend labels, which makes recall difficult (41 steps is a lot), but the front-panel design was upgraded in November 2015 with numbers around these knobs. 

Shortly after my BC501 arrived for review, my friend Don Gunn picked one up. Don is a great engineer based in Seattle; he's worked on lots of legit records and in plenty of good rooms, so I asked if he wanted to contribute some thoughts to my review. He did: 

"Let me start by saying loudly and proudly that I love mix bus compression. The first thing I do when working on an SSL desk is engage the Quad Comp in the center, even when tracking, because (1) this is also the kind of compression I'll wind up using in the mix, and (2) stuff starts to sound 'like a record' from the tracking stage and will inform the decisions I make when applying compression to various instruments during tracking. Come mix time, 99% of my mixes start with the bus compressor engaged, so again, it informs any decisions I make about overall dynamics. What I don't do is beat the snot out of the bus compressor; I'm looking for that ineffable, magic 'glue,' as it's come to be known. The meters of my bus compressor may only show 1 or 2 dB of gain reduction, but upon bypassing the compressor, I hear the life and excitement drain out the mix. 

"I've owned and used many compressors that I've put into service as mix-bus units, and generally, I'm trying to attain what I love most about the Quad Comp on an SSL, but for one reason or another, I never feel like the piece of gear is giving me what I want to hear. I've even owned the Smart Research C1 and use a C2 regularly at Studio Litho here in Seattle. Both were designed by Alan Smart, the former SSL employee who also designed the Quad Comp in the SSL 4000. 

"Enter the BC501. This 500-series stereo compressor borrows features from TK Audio's 1RU-height BC1-S, as well as their BC2-ME mastering compressor. All three are VCA-based compressors, so their hearts are similar. Also brought along from the BC2-ME is the THD button, which adds subtle even- order harmonics to the input signal; it's one of those 'fairy dust' controls that I don't think I've turned off since putting the BC501 in my rack. As a solid-state, transformerless unit, there isn't a lot of 'color' to be had just passing signal through the BC501, short of what it's doing in the VCA circuit (this isn't a bad thing), so the THD option is a welcome addition. 

"One of my favorite features of the BC501 is the variable high- pass filter on the sidechain detector. This lets you set up a HPF to prevent low-frequency signals from causing the compressor circuit to over-react. I can create a giant, low-end package of kick drum and bass guitar, or low synths in a mix, and not have them freak out the detector circuit in the BC501, causing too much gain reduction to occur and squashing the dynamics of the mix, or making the whole mix pump and breathe when I just want it to sail through and sound huge. There's even a stereo 1/8'' jack input on the front panel of the BC501 to allow for an external sidechain if you want to use the compressor as a de- esser keyed from another instrument/track, or get massive EDM- style pumping on a track by sending the music mix through the BC501 and keeping the kick drum separate from the main mix while also using it as the sidechain source. 

"Now that I've gone on about the BC501 in the context of a mix, the first thing I did after I got mine was to use it on a tracking date on a pair of overhead mics. On an appropriately dynamic drum track, with 4:1 ratio, 30 ms attack to let a full transient through, auto release, and threshold set to give me about 4 dB of compression, I got a huge drum sound just from the spaced pair of overheads. Adding in some kick and snare close mics made the drums sound like they were right in front of me. I've also used the BC501 during a mix on drum overheads (giving over the mix bus to my pair of Daking FET II compressors [Tape Op #36] for this particular song), where I was able to try out more settings. I landed on 2:1 ratio, 10 ms attack, and 50 ms release — again setting the threshold to never take off more than 4 dB. 

"Shifting back to mix-bus duties, I usually bounce between 2:1 and 4:1, depending on the density of the mix; attack/release combos of 10/50 ms or 30/Auto; threshold set to give an average of 2 dB gain reduction; and THD engaged. I've found my perfect formula for 2-bus compression. 

"Aside from that one time using it on overheads, my BC501 hasn't left my mix bus. It's the compressor for which I've been searching. I've mixed more than 30 songs through it since buying it a couple of months ago. For each mix, as I start hitting the point where the mix has me smiling and I'm reaching 'the zone,' I take a second to press the bypass and THD buttons to make sure the BC501 is bringing more to the mix than without it. On every mix, I've pushed both buttons back to the on position and continued to smile." 

You know how some gear just feels good to use? The TK Audio BC501 is one of those. I bought my demo unit. 

Tape Op is a bi-monthly magazine devoted to the art of record making.

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