The Most Coveted Sound in Studio History — Reimagined
Easily among the most coveted and time-tested pieces of hardware in studio history, the Fairchild-style compressor has proven its unrivaled musicality across more than five decades. The Undertone Audio UnFairchild 670M II offers a painstaking re-creation of that classic sound, reinforced by modern features that today’s engineers are sure to appreciate. One of the reasons for the original circuit’s longstanding appeal is its versatility, as it delivers gentle level smoothing and explosive dynamics control with equal confidence. That said, the true value of this design is its peerless sound, which is guaranteed to make any recording leap out of any listener’s speakers. Recognizing a few limitations of the original, UTA made careful adjustments to the circuitry to greatly improve tube lifespan and reliability, while also introducing a host of exciting new features never before available on a Fairchild-style compressor. For starters, the six original preset Time Constants have been bolstered by four variable Time Constants with independent Attack and Release controls. Beyond that, the UnFairchild 670M II features multiple M-S modes, sidechain processing, true bypass, per-channel Gain Trims, front-panel DC Threshold, and optional feed-forward operation. With the UnFairchild 670M II, you can stop yearning for unobtanium and finally get your hands on an extraordinary circuit flexible enough to handle every compression task across every production.
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Intelligent soft-knee dynamics control
Behind the buttery vocal sound of the Beatles was a secret weapon: the Fairchild-style compressor, of which Abbey Road owned several. Sweetwater is glad to report that the UnFairchild 670M II carries similar DNA, housing 20 tubes and 14 transformers working in concert to produce a compression character that no other circuit topology can replicate. Variable-mu gain reduction delivers a natural soft-knee curve, with attack times fast enough to catch transients and release times long enough to let the music breathe. And because it’s program dependent, the compression ratio responds intelligently to the source, remaining subtle on small peaks, then tightening into brickwall territory when the signal demands it.
Where vintage legacy meets modern engineering
The Undertone Audio UnFairchild 670M II departs from the original Fairchild in several meaningful ways, all of them improvements. The audio path uses CineMag re-creations of the original transformers, with only minor adjustments made to optimize the gain structure. The sidechain circuit has been streamlined for improved reliability without sacrificing the original unit’s legendary sonic characteristics. One of the most consequential changes is a reduction in plate voltage to the 6386 tubes. Original units run at such high plate voltages that the manufacturer’s own manual recommends replacing the tubes every six months — a significant expense. That maintenance burden is one reason so many surviving originals sound markedly different from one another and why some sound outright poor. With lower plate voltage and a quality set of tubes, the UnFairchild 670M II is built to run reliably for years. You also get an expanded control set, adding variable Time Constants with independent Attack and Release controls, front-panel DC Threshold, sidechain access for processing or EQ, per-channel Gain Trims, true stereo linking, multiple M-S processing modes, feed-forward compression, meter calibration, true bypass, and output metering. Together, these additions deliver the full sonic legacy of the original with the flexibility a modern engineer would expect.
Undertone Audio UnFairchild 670M II Features:
- 2-ch. variable-mu tube compressor based on the legendary Fairchild-style unit
- Augmented with modern features aimed at today’s engineers
- Delivers gentle level smoothing and explosive dynamics control with equal confidence
- Class A circuitry with 20 premium tubes and 14 CineMag transformers
- 6 original preset Time Constants are bolstered by 4 variable Time Constants with independent Attack and Release controls
- Multiple M-S modes for mixes with increased width, depth, and focus
- Access to processing or EQing the sidechain signal
- True bypass preserves your signal when the unit isn’t in use
- Per-channel Gain Trims for precise matching of the left-right balance
- True stereo linking — a must-have for mastering applications
- Front-panel DC Threshold for immediate access
- Optional feed-forward operation unlocks tighter response, predictable attack/release behavior, hard limiting, and more
- Straightforward meter calibration and output metering
- Lower plate voltage greatly increases tube lifespan
