Home » Recording Resources » Featured Reviews » Universal Audio SSL 4000 G Bus Compressor Plug-In Collection

By Alex Hawley

Universal Audio recently released a completely redesigned emulation of the Solid State Logic 4000 G Bus Compressor, part of UAD’s v9.2 update. The plug-in comes paired with a DSP-light legacy version, and is available exclusively for UAD-2 systems and Apollo interfaces. For those who already own the legacy plug-in, an upgrade price of $149 is offered for the new emulation, while buying the collection will cost $299.

The UAD SSL 4000 G is the product of a painstakingly detailed circuit level emulation of SSL’s legendary VCA bus compressor. The engineers at UA captured every nuance of the hardware’s circuit behaviors, including SSL’s control voltage summing. The original hardware unit is famous for a powerful and punchy sound, and having an innate ability to add glue to the mix bus. Its unique sound can be heard on countless records from the 1980s up through the present day. 


The landscape

The SSL 4000 G Bus Compressor is a favorite 2-bus compressor for many engineers. Operation is simple, and it doesn’t require much finesse to be used effectively. The UAD emulation includes all of the original controls found on the hardware version, with an accurate GUI presentation. The main controls include Threshold, Make-Up Gain, stepped Attack times (ranging from 0.1 milliseconds to 30 milliseconds), stepped Release times (ranging from 100 milliseconds to 1.2 seconds plus Auto), fixed Ratio settings, and an In/Out button.

The Ratio settings include 2:1, 4:1 and 10:1, which are designed with a variable knee. The variable knee allows you to toggle between each Ratio setting without affecting gain reduction or perceived loudness, as the SSL circuit modifies the threshold for each ratio. This allows you to just focus on the changes in character.

In addition to the original hardware controls, there are a few bonus parameters added for the plug-in version. The first digital feature is a Sidechain filter, a 12 dB/octave highpass filter with continuously variable corner frequency that ranges from Off to 500 Hz. Using a sidechain can help achieve well-rounded and transparent compression by allowing the low-frequency content to pass through without triggering any gain reduction (and without reducing bass content on the source material).

The next parameter that is exclusive to the plug-in is a very welcome Mix knob. This allows you to blend the dry and compressed signals together, creating parallel compression without the need for additional busing or routing.

The Headroom parameter, also not found in original hardware, allows adjustment of the internal operating reference level. This setting has a stepped range from 4 dB to 28 dB, with a default value of 16 dB. This gives you some extra flexibility on how much headroom you are mixing with, so you can have a more useful range of threshold control.

Just like on the original SSL outboard units, the Auto Fade function is useful when a song needs an automatic and smooth fade-in or fade-out. This parameter can be automated, and has a range from 1 to 60 seconds using SSL’s signature fade curves.


In the mix

The original hardware SSL 4000 G was already one of my favorite compressors on the mix bus. UAD’s most recent emulation sounds distinctly different from the legacy plug-in, and does an amazing job of capturing the signature SSL sound. While the legacy version sounds punchy and full, the new emulation seems to achieve the same punch in a slightly more transparent, less snappy package. It also sounds like it has a bit more midrange detail, clarity, and openness to the top end.

One of my starting settings for the 2-bus starts with the 4000 G set with a 2:1 ratio, and less than 3 dB of gain reduction. It’s transparent at this setting, but adds a nice cohesion to the mix that might otherwise be lacking. This compressor works wonders in this role; its tight bottom end and clear midrange creates a glue that really helps tie the whole mix together. The great thing about the SSL 4000 G is that you don’t have to be afraid to push it harder, either—it responds well, with energy and power. The character from pushing it harder especially shines in a pop or rock context.

I love the flexibility of the plug-in’s added Sidechain filter and mix knob. I’ve turned to these features quite a bit. The SC filter is very useful for bass-heavy mixes that need a little room to breathe. If the kick or bass is a major component of the mix, generally speaking, you’d normally have to set the mix bus compressor with fairly tame settings so as to not overcompress. I’ve been mixing a reggae project recently that needs a healthy bottom end, and enabling the SC filter allowed me to get the glue I wanted on the body of the mix without choking the bottom. Works like a charm!

Even though the SSL 4000 G has historically been used as a mix bus compressor, this thing sounds absolutely huge on the drum bus. I love to set an aggressive 10:1 Ratio with fast Attack and Release times until the compressor pumps and breathes. From there, I’ve been experimenting with the plug-in’s Mix knob to maintain some of the transients from the dry signal, while still benefiting from all of the energy and power in the wet signal.


Closing thoughts

I’ve always been drawn to SSL for having an iconic and musical sonic characteristic. There isn’t much the 4000 G Bus Compressor doesn’t sound good with, making it a solid candidate for any engineer’s desert island gear list. UAD’s end-to-end circuit emulation does an incredible job of capturing the sound and vibe of the hardware counterpart; it truly sounds more like an SSL than it does like a plug-in.

This compressor is very intuitive and easy to use effectively, and more functional than ever with UAD’s added feature set in the Mix knob and Sidechain filter. I am impressed that UAD offers both the legacy version and new emulation for such a low price; each of the two plug-ins serves its own purpose, which makes this collection a very appealing one.


Delivery: Web download

Format: UAD-2 and Apollo hardware; host plug-in runs on macOS 10.10+ and Windows 7+ (64-bit)

Copy Protection: software runs only on UAD hardware

License: Single user account allows installation/authorization of purchased plug-ins on up to six UAD devices (including up to four Apollo interfaces)

Documentation: downloadable PDF manual

Price: $299 ($149 upgrade for owners of the original SSL 4000 G plug-in)

More from: Universal Audio, www.uaudio.com


2017 Reviews