SSL’s Sigma Is an Innovative Analog Summing Box

There’s a lot of advantages to digital workstations, but the big two are total control and the speed of instant recall. If you mix in the analog domain it can turn into a piece of performance art, with the mixing engineer and several band members running around the board moving faders at just the right moment. This can be avoided to some extent by automating track output levels in Pro Tools/Logic/etc, but that can lead to noise floor issues. The recall problem is even harder to get around. If you have to jump between recording sessions you can take copious notes but inevitably something just sounds a little different when you open an old mix.

Mixing inside your computer (“in the box”) has none of those downsides, but many in the recording industry swear by the benefits of analog mixing. The tones just gel better as a cohesive uni,t and you end up with a fuller, clearer mix. I’ve heard A/B comparisons and it seems to be the case but I’ll admit that the difference is usually subtle. There have obviously been incredible sounding mixes that never left the digital domain. In my opinion, the bigger benefit of an analog mix is you get to use all that sweet outboard gear, the best of which almost always sounds better than plugins.

But what about the recall and automation problems? Metal in particular is dependant on a tightly controlled mix, because the sound is so dense. Often the solution is a summing box: essentially a mixer with no faders or knobs. It bypasses the hassles of a mixing board (not just in use but the maintenance). Most of your mix is controlled inside the computer, but then sent out as individual tracks of audio that are summed back together “outside the box.” If you want to mostly use plugins but you have a few DBX 160a compressors for the kick and snare and a Distressor you want to use to squash and distort a vocal, for example, this is how to get the best of both worlds.

With that preamble out of the way, how is SSL innovating in the field of summing mixers? Most popular summing boxes, like the Dangerous 2-Bus, are essentially 8 stereo inputs that get mixed together at unity gain (the level they go in is the level they come out). The SSL Sigma is a wholy different beast. It’s closer to an actual mixer in that it has digitally controlled volume settings for each channel. This means the Sigma itself controls track volumes—they don’t have to be controlled by the DAW.


There’s also a few other useful features that SSL smartly included to appeal to the small project studio crowd, things you’d usually find on a prosumer interface like an Avid MBox Pro or Apogee Ensemble. The Sigma has a talkback input, two sets of monitor outs, and a headphone jack. Essentially, with the SSL Sigma, paired with a PCI interface box or two and a couple choice pieces of outboard gear, you have a serious mixing setup (assuming you also have the monitors and acoustics to match).

SSL have added a few welcome tweaks to the summing box while adding all the features of a monitor controller, creating a new product subcategory in the process. As metal gets increasingly digital and recording budgets go from small to nonexistent, it’s likely we’ll see more gear along these lines.

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Chris Alfano has written about music and toured in bands since print magazines and were popular. Once in high-school he hacked a friend's QBasic stick figure fighting game to add a chiptune metal soundtrack. Random attractive people still give him high-fives about that.