Solid State Logic has just released its most advanced bus processor ever: THE BUS+ ($2899). Much more than a simple bus compressor for pumping up your mixes, this digitally controlled analog processor includes a host of features from SSL’s most popular bus compressor modules like mid/side mode, dynamic EQ, harmonic distortion and wet/dry mix. Whether you’re building an analog mastering chain or just love the SSL sound on your drum mixes, this unit is the perfect centerpiece for your racks.

We had the chance to put the SSL BUS+ bus compressor to the test. Watch our demo below to learn about the key features of this versatile new bus compressor and hear how it sounds on the mix bus and drum bus.


THE BUS+ follows a similar design philosophy to the SSL Fusion analog master processor, combining a set of useful tools that give it the flexibility to address any mixing situation. Need ultra-transparent signal leveling for mastering? Want to give your mix a bit more analog character? How about dirtying up your drum bus with harmonic distortion? THE BUS+ lets you do it all—and more—with an easy-to-navigate front panel and handy stepped controls for perfect recall.

Here’s a quick overview of what the new SSL BUS+ has to offer:


  • Authentic SSL Bus Compressor circuit
  • Four modes of operation: Classic Stereo, Σ S/C Stereo, Dual Mono and Mid-Side
  • New Attack and Release time constant options 
  • Three distinct compression coloration options can be combined or used individually:
    • 4K Mode provides variable harmonic distortion to bring some 'grit' to the mix
    • LOW THD Mode reduces low-frequency distortion for a cleaner bottom-end
    • F/B Mode offers a more 'relaxed' style of compression
  • Built-in two-band dynamic EQ 
  • Stepped controls designed for mastering and precision processing applications
  • Transient Expander effect
  • Configurable processing order
  • Variable side-chain high-pass filter up to 300 Hz in 10 Hz steps
  • Mix control for instant parallel compression

These specs are certainly impressive, but they only tell part of the story. Let’s dig a little deeper into the features and get to the heart of what makes THE BUS+ so powerful.


At its core, THE BUS+ retains the character of the original SSL Bus Compressor, using high-grade components like 2181 THAT VCAs in the signal path to ensure pristine sound quality with analog character. But the unit also adds a host of tonal options, routing features and adjustable parameters that give it infinitely more utility than its forebears. From its three mix-and-match coloration switches to its advanced dynamic EQ and sidechain features, THE BUS+ is truly the most impressive incarnation of the SSL Bus Compressor yet—but it's also so much more.


Traditional analog gear sounds great, but has one fatal flaw—knobs and switches can get dirty over time, introducing noise and distortion and eventually failing. Thankfully, SSL has solved this problem with their MDAC (Multiplying Digital to Analogue Converter) technology. Using digital encoders and buttons to control analog components inside the unit, THE BUS+ gives you the accuracy and reliability of digital control while ensuring your sounds remain 100% analog throughout the entire signal path.


The two channels of THE BUS+ can be used in four different modes. The traditional Stereo allows you to process stereo signals like drum busses or full mixes using one set of controls for both channels. Sigma Sidechain (Σ S/C) mode functions similarly but sums the left and right sidechain channels for more responsive sidechain behavior. Dual Mono mode frees up the unit to process two signals independently using the left and right sets of controls. Finally, Mid/Side mode lets you process the mono center information in a mix independently from the left and right stereo information, which is handy for mixing and indispensable for mastering.


Used extensively by mastering engineers but not often seen in hardware bus processors, dynamic EQ allows you to control frequency response as the music changes, rather than applying a static EQ which affects the entire mix. THE BUS+ features a two-band dynamic EQ with independent controls for the low and high bands. Turn the knobs to the left for a compression effect, which attenuates frequencies when they cross the threshold or turn the knobs to the right for an expansion effect, which does the opposite.


THE BUS+ features three distinct compression coloration options which can be combined or used individually, giving you a rainbow of tonal options to choose from. Based on the sound of the iconic SSL 4000 console, 4K Mode features nine levels of harmonic distortion to dirty up your mix just how you like it. Low THD Mode reduces the low-frequency distortion caused by compression, cleaning up the bottom end for a less muddy sound. Lastly, Feedback Mode alters the compression characteristics for a more 'relaxed' style of compression. Try different combinations to find the perfect character for your mix.


There’s much more to this unit’s bag of tricks than we can cover in one blog, but there are a few more features you should know about. A wet/dry control lets you mix the processed signal with the original, making it easy to dial in parallel compression with a perfect phase relationship between the signals. Individual VU meters (with calibration screws) for each channel give you a clear view of how much compression you’re applying, while stepped controls let you recall settings with perfect accuracy. There’s even a secret minigame you can play to unlock the Transient Expander effect!

Jeff LeibovichIf you have any questions about the Solid State Logic BUS+ or would like to purchase one, we're here to help! Please contact a Vintage King Audio Consultant via email or by phone at 866.644.0160.