Focusrite Blue 330
A mastering compressor-limiter that splits compression and limiting into two sidechains feeding a single signal-path VCA. It is the Red 3 reworked for the cutting room.
Overview
The Blue 330 is Focusrite's Red 3 compressor and limiter rebuilt as a mastering tool. The company's own literature says so plainly: the 330 "represents the transformation of the Focusrite Red 3 Compressor and Limiter into a Mastering format." Focusrite billed it as a companion to the Blue 315 isomorphic equaliser, the two units forming the analogue processing core of a mastering chain. The front panel has an anodised electric-blue finish, and the ergonomics were tailored for the mastering engineer rather than the tracking room.
The topology is what sets the 330 apart. A conventional compressor uses one detector that rolls over from compression into limiting. The 330 splits the two processes and implements them through a single proprietary VCA in the main signal path, fed by two separate sidechain circuits - one for the compressor, one for the limiter - each with its own VCA. As Focusrite explained it, the limiter only catches the peaks that survive the compression stage, so the result is cleaner and less intrusive than a compressor that rolls over into limiting. Owners and mastering engineers tend to describe the effect as gain reduction that stays out of the way.
The control set was scaled for mastering rather than general dynamics work. Most of the rotary functions are switchable rather than continuously variable. Stepped controls allow precise, repeatable settings and easy channel matching, which is what a cutting room needs. The input gain and make-up gain controls share the same sensitivity, allowing what Focusrite called "tandem contra operation" - raise or lower one and the other tracks, so the rest of the settings don't need re-adjusting. Two PPM meters indicate input, output, or gain change. The unit was designed primarily for stereo operation, with a single set of controls rather than the dual-mono layout of a tracking compressor.
The 330 was revised during its run. By 1997 Focusrite had upgraded it with a quieter, lower-distortion Class A VCA circuit and added a lookahead limiter achieved with an audio delay. That matters for a unit whose job is catching peaks without smearing transients. Buyers of a used example should establish which version they have, since the two revisions are not the same circuit.
The Blue 330 found its way into serious mastering rooms. It appears in the equipment lists of working facilities and on records. An EQ Magazine feature on the 50th-anniversary reissue of Kind of Blue lists a Focusrite Blue 330 among the outboard in the chain, alongside a Blue 315, EAR equalisers, a Manley Massive Passive and Variable Mu, and a custom Muth console. Mix (June 1996, p.88) framed the Blue 315 and 330 together as Focusrite's answer to mastering engineers' demand for precise equalisation and dynamic control in an era of mixed analogue and digital technology.
Collectors and mastering engineers note that the 330 is a specialist's tool rather than a general-purpose compressor. Its stepped controls and stereo-only layout make it less flexible in a tracking context than the Red 3 it derives from, and the single set of controls means it isn't the box for dual-mono work. It does clean, separated compression and limiting with repeatable settings, and it has the build quality Focusrite reserved for its mastering line, with high-quality switches throughout for long-term reliability. Prices and current market values are not documented here. The unit turns up in professional sales rather than the general used market, and the lookahead-equipped later version is the one most often sought. Production years are not confirmed in available documentation.
Similar items on eBay
No exact Focusrite Blue 330 listings are live right now — these searches show current Focusrite and similar vintage audio gear on eBay:
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.