Solid State Logic: THE BUS+ Bus Compressor

There is an entire market segment devoted to bus compression. While there are some unique designs in circulation, the concept and function is usually based upon the compressor module found on large format SSL consoles. While the Oxford-based company offers rack and 500 Series versions of the compressor, THE BUS+ expands the original with increased functionality and significantly improved recall abilities. It’s not just for mixing. Many mastering engineers keep a bus-type compressor in the rack. To provide a more encompassing review of THE BUS+, we’ve enlisted mixing engineer Chris Short to add to my observations.
His notes are first:

I cut my teeth on analog desks. When I finally got to work on an SSL, the first thing I did was pull up a mix and hit the In button on the master bus compressor. From that day forth, I couldn’t do a damn thing without it. Even if I’m tracking in the box, I’ll have a low latency compressor strapped across the mix. In the words of people much wiser than I, the bus compressor is the “engineer’s little helper.”

I recently moved Alpaca Ranch Recording from Orlando to Chicago. The expense of moving (and everything else associated) led me to swap my SSL XLogic G Series compressor [Tape Op #47] for a more affordable option. I ended up with a well-made clone, which, honestly, rocks. While finishing up an LP for Milwaukee natives Onyx Koan, a post-reggae record with some rock sprinkled in, I saw how SSL’s new THE BUS+ might work in my setup. I expected it would sound excellent (almost everything SSL makes does), but how different would it be from what I already have? Plus, as we all have to make a living here, is it worth the cash?

I don’t tend to hit the mix bus too hard – maybe taking off 2 to 3 dB at a 2:1 ratio with a slow attack and a fast release. All the summing happens in the box, but when the last thing the music hits is analog, a little unpredictability occurs, giving the mix some vibe. Maybe I’m kidding myself, but the clients are happy, so I’m happy.

Given we had a somewhat limited timeline to review THE BUS+, I began with its intended use as a master bus processor. I patched it in with the same settings my clone has been configured to since time immemorial and let her rip. Upon first listening (and excluding many super cool features that this particular compressor has), THE BUS+ sounded pretty much like my clone, which made me very happy. Without much fuss, I got a controlled “reigned-in” compression setting, knocking around 2.5 dB off the top. It sounded outstanding, but I’m not sure I could hear a big difference between the clone and the SSL – I hadn’t gotten to the cool stuff yet.

This compressor has a TON of options, so I started hitting buttons and throwing caution to the wind. The F/B button switches between feed-forward or feed-back compression. Forward seemed to bring out a little more detail in these tracks. For example, the picking of an acoustic guitar had a little more nuance. Pretty cool. I have a feeling I’ll be using Forward most of the time. The 4K mode, which, as the name suggests, produces SSL 4000 Series compression qualities – and it does what it says on the tin. I appreciated how the 4K mode seemed to add a little forwardness and saturation, and would probably leave it engaged most of the time. After reading the manual, I discovered that this mode has nine distortion settings – NINE! Given that we are now in the world of pristine digital recording, I always want more “good” distortion. Torque it down ‘til it snaps, then back off half a turn. THE BUS+ imparted fullness and desirable low mid thickness. Even going to the heaviest setting didn’t change things too dramatically. Side Note: the button on the top far left is a Low THD button, which I won’t bother with because what’s the point? If we wanted low THD, we would be using a plug-in. (Garrett disagrees, but more on that in a bit).

The Dynamic EQ is really cool. And it will, I’m sure, be used relentlessly once users have time to delve into all its possibilities. What frequencies and ratios are the Dynamic EQs set to? Only one way to find out. I gave in, and downloaded the complete manual. Holy crap, THE BUS+ can do a lot! In a “get a sound fast” drill, I enabled the two-band Dynamic EQ. Crank up the HF knob for more highs, crank up the LF for more lows. And vice versa. For my test song, I set the LF band around 100 Hz and the HF around 6 kHz. There isn’t much control over attack and release times, which was somewhat disappointing. One has to push a lot of buttons to make the EQ points happen. I expect most people will need a cheat sheet until they become accustomed on how to navigate the THE BUS+’s controls. Although impressed, I began to get overwhelmed by all the possibilities.

The unit is digitally-controlled analog, which makes excellent sense considering the relatively arbitrary tolerances of control pots and the like. However, as much as SSL touts the recall ability of the unit, how can you truly recall everything with soft buttons and key presses? I have a feeling most users will find the settings they like and let the unit live there. That’s what I do with some of my gear. But if THE BUS+ is installed in a facility with many engineers running in and out, recall could be difficult without more in-depth documentation or an easier-to-use interface. All of that leads to my one major complaint: why does THE BUS+ not have a USB connection and GUI? That would be a game-changer for devices this complex, not to mention making it more flexible and maybe even automatable.

Overall, THE BUS+ does precisely what it promises: SSL compression, which we all know and love. Useful? Absolutely. Intuitive? You’ll spend some time with the manual on this one to get the most out of it. I understand entirely what SSL was going for here: A master bus processor to rule them all that will please everyone by offering a bit of experimentation. In use, it does very well, and anyone who mixes into THE BUS+ won’t be disappointed.

From a mastering perspective, I sometimes hold contrary opinions to Chris’ on some items. For example, I had no use for the THD feature. If the mix engineer wanted grit, they would have put it there. Although I like feed-forward designs in mixing, a feed-back topology generally tends to be less conspicuous. Aside: Although THE BUS+ theoretically uses a feed-back design, the signal feeding the sidechain originates from a feed-forward position in the circuit. Engaging the F/B switch derives the sidechain’s signal feed after the gain-reduction VCA of the audio path. So, that could be considered a feed-back position – end soliloquy. For mastering purposes, I avoided the 4K mode – in the final stage of the production chain, the less intrusive approach is often the best tactic. Finally, although I can see the dynamic EQ being an exceptional feature for mixing, I require the levels of control only found in plug-in formats. Undoubtedly, THE BUS+ feature set results from innumerable design hours and impressive intellect. One example, to prove my point, is when setting the dynamic EQ, THE BUS+ utilizes the VU meters to display Frequency Points and Q values. That is brilliant.

Chris and I both agreed that the compression quality is reason enough alone to purchase THE BUS+. I was probably a bigger proponent, suggesting it bordered on sublime. The mythical ideal of tight impact, followed by a round, perfectly-tuned essence, concluding with a decay that just sounds right – that’s attainable with this device. Since I’ve had to install custom sidechains on most of my dynamics gear, I was pleased with the adjustable sidechain filters and balanced external loop. Having a flexible built-in option saves time, money, and rack space.

We also concurred in our assessments of the complexity of features. There is not enough column space to discuss everything. However, some, like Operation Modes, are too important to skip. Here SSL gives us four: Classic Stereo, Summed S/C Stereo, Dual Mono, and Mid-Side. Switching among the modes provides distinct results, even with the same R/T/A/Rel settings.

One way of looking at it concludes that we now have four different compressors for every setting. Expanded control ranges are next. Take the best bus compressors out there; most lack settings I commonly require, or that people want. For example, where a 2:1 ratio is usually the lowest most compressors have, SSL has added 1.5:1 and 1.3:1. If that’s not enough, three negative ratios (-2.5, -1.5, and -0.5) can be used to reduce the output signal once it exceeds a threshold, placing the audio level below that threshold. Not only can THE BUS+ control extremely loud signals (sorry, live sound engineers, I’ve just informed you to get in line to purchase one or more), it can achieve massive pumping effects. Blend that using the Mix control, and you’ll have access to sounds that used to require several pieces of hardware and spare console channels to produce. The Release control is an 11-position pot ranging from .05 to 1.2 seconds, plus two Auto modes. It’s worth noting that .05 (50 ms) is the fastest setting on an SSL compressor to date. Make-up offers -10 to +20 dB, but mastering types will appreciate the Fine setting, which changes the range to -5 to +10 dB in 0.5 dB increments.

Nowhere did we agree more than on the issue of recall and usability. A USB connection paired with a platform-independent GUI or a VST/AU/AAX plug-in would be remarkable for the THE BUS+.

I would go as far as suggesting it would decimate sales of competing compressors. Given how many features require multiple button combinations to access, and considering the increase of in the box production, a GUI would allow faster sound acquisition, impeccable recall, and cause us to resent most of our other gear for lacking the same.

I do have one area of frustration in that the control layout feels like it was designed by a graphics expert instead of an audio engineer. Specifically, the right channel is a symmetrical mirror of the left, rather than a duplicate. I often utilize dual mono. I need to make eyes-closed adjustments while focusing on the music and find it intuitive to simultaneously reach for controls with matched layouts. Having to look down and find the correct knob breaks concentration, distracting the auditory decision-making part of my brain.

In the end, we both appreciated the quality of THE BUS+’s compression section. SSL could have released this unit without additional features, and the list price would still be reasonable. Likewise, adding feed-forward/feed-back detectors, four stereo modes, and Mix blend make an outstanding compressor more useful to professionals. So again, just on the merits of the compression quality and nothing else, I recommend this unit. Taking it a step further, if you’re someone who enjoys tweaking and is willing to learn how to get the most out of the many additional features, you’re going to be amazed at the what you can do with THE BUS+.