Plug-In Power: The Neve 33609 Bus Compressor
By Dave Crane

UA's long-awaited digital re-creation of Neve's 33609 bus compressor will be released with version 4.4 of the UAD drivers and software. The 33609 is unique among the UAD's fine collection of vintage compressors, as it is our first model of a diode-bridge type compressor, as well as our first dedicated bus compressor model.

Many controls on early bus compressors are stepped so that each channel can be set up identically. Advances in electronics have allowed some controls to be continuously variable, but the majority of compressors marketed today as bus compressors have some stepped controls, typically the release times and input and output level controls. Auto-release modes are also common in bus compressors.

“The 33609 is our first model of a diode-bridge type compressor, as well as our first dedicated bus compressor model.”

The Neve 33609 started its life as various mono bus compressors installed in Neve consoles in the late '60s and early '70s. First introduced as the 2252 in 1968, it was a hit for musicians and engineers worldwide for over 30 years. The 2254e revision was installed in mono pairs in many 80-series consoles. The channel strips that fed this compressor were the 1073 and the 1081. Obviously the 2254e was in some good company!

Soon, many engineers were removing the pair 2254e compressors from the consoles, racking them up with a power supply, and using them in stereo or dual-mono mode. Neve picked up on this trend, and after a few refinements, the company introduced the 33609 bus compressor. It was followed a couple of years later by the 33609C and finally the 33609J. You can read more about the analog 33609 in May's "Analog Obsession" article.

Modeling this masterpiece was not easy, but our engineering team worked the usual magic. When you put the 33609 on a drum bus, we think you'll agree that it is a stellar compressor, whether or not you've hear the real thing. Besides what your ears tell you, another indicator of the sheer magnitude of modeling such a complex analog circuit is the fact that one stereo instance takes around 70% of a UAD-1 processor at 44.1k! You can barely fit two mono versions as well. But don't worry, we've made an SE version, which can get 9 mono and 7 stereo instances at 44.1k. While it does not include all the nonlinearties that make up the real thing, it still sounds great. You can read more about modeling the 33609 in the "Ask the Doctors" article in the August WebZine.

The completely stepped-controlled 33609/SE is made up of separate compression and limiter sections, each with its own threshold, recovery and bypass controls. Two of the recovery selections for each section are dedicated to a program-dependent auto release. The compressor section also offers five ratio selections and 20 dB of make-up gain, while the limiter offers a fast or slow attack. The mono/stereo switch allows coupling/decoupling of the left and right gain reduction elements. DAW software-only control enhancements include an additional stepped 20 dB output gain and a link switch allowing ganged left/right control of all parameters.   

In the two movies below, I use the 33609 on a full drum kit, and then on some stereo program material. Listen to the VO for details.