Fairchild 670

Summary

Abstract

The Fairchild 670 is the most legendary and expensive compressor in audio history. A stereo vari-mu tube compressor originally designed in the 1950s by Rein Narma, it became synonymous with Abbey Road Studios and the Beatles’ recordings. With fewer than 1,000 original units ever built, vintage Fairchilds command prices from $30,000towellover$75,000. However, the community has a surprisingly grounded perspective on the Fairchild mystique. BatMeckley recounts a conversation with Geoff Emerick (who engineered much of the Beatles catalog): when asked about the Fairchild’s “legendary contribution” to the sound of music, Emerick responded “…eh” and said he would have been just as happy reaching for an UREI 1176. The Fairchild is valued more for its “box tone” — the sound of audio simply passing through the unit — than for its compression behavior.

Key Characteristics

• Type: Vari-mu (variable-mu tube)
• Topology: Push-pull tube circuit using matched pairs of remote-cutoff tubes (6386 in original design), transformer-coupled input and output, with approximately 20 tubes per channel
• Notable Features:
  • Stereo operation (670) or mono (660)
  • Six selectable time constant positions controlling attack and release simultaneously
  • Lateral/Vertical mode for stereo encoding (originally designed for vinyl cutting)
  • Extremely smooth, program-dependent compression behavior
  • Massive physical size and weight (~65 lbs)
  • The “box tone” — the harmonic richness of audio passing through the tube stages even without compression engaged

Use Cases

When and why engineers reach for the Fairchild:

• Stereo bus / mix bus — The classic application. The smooth vari-mu behavior gently glues a mix together. However, Edward Rivera notes it is “absolute shite on blast beats.”
• Box tone / color — hyanrarvey: “Box tone on the Fairchild is fucking awesome. Compression eeeeeh.” Multiple community members value the Fairchild more as a tone box than as a dynamics processor.
• Mastering — Nomograph Mastering references the Fairchild alongside other units that have been “marketed and sold as the Panacea at various points.”
• Vocals (debated) — BatMeckley has used real Fairchilds multiple times on vocals and “every single time I’ve ended up taking them off.” CK had a transformative experience tracking vocals through an UnFairchild — “I had never heard vocals tracked like that.”

Settings & Sweet Spots

Commonly referenced settings from experienced engineers:

• Mix bus glue: Gentle settings with minimal gain reduction (1-3 dB). Time constant positions 1-3 for faster material, 4-6 for slower, more program-dependent behavior.
• Box tone only: Run audio through with minimal or no compression engaged to add harmonic richness from the tube stages. Hyanrarvey describes this as the primary appeal.
• The UnFairchild approach: cian riordan, who has owned a V1 UnFairchild since 2012, prefers its more aggressive and limited character: “If I’m going to go out of the box for something, I don’t want the results to be subtle.” The V2 UnFairchild is “infinitely more flexible and the circuit has less THD and noise… but like, is kinda boring for my tastes.”
• Avoid pushing gain too hot — Rob Domos listened to demos and noted: “Two of them were clearly pushing the gain too hot in a slightly 1950s kinda way.”

Comparable Alternatives

Unit	How It Compares
Undertone Audio UnFairchild	The most respected modern Fairchild-inspired unit. cian riordan owns V1 SN from the original 10-unit run. peterlabberton: “The only Fairchild-ish thing I’d ever consider… actually flexible.” Still considered overpriced for utility by some.
Heritage Audio Grandchild 670	A 500-series Fairchild at ~$2,000. Bryan DiMaio and the community were amused but skeptical. Rollmottle diagnosed the market as suffering from “Fairchild Fatigue.”
Telefunken/Fairchild 660 Reissue	David Fuller shared that the guy behind Telefunken US is relaunching Fairchild. Community reaction was muted — “Whatever mystique they had is nowhere to be found when there are already more than half a dozen reissues.”
UREI 1176	Geoff Emerick told BatMeckley he would reach for an 1176 and be just as happy. Serves a different compression purpose but fulfills the same role in many contexts.
Plugin emulations	Acustica Ultramarine and various UAD/Waves options exist. CK uses Acustica Ultramarine as a reference point.

Common Mistakes

• Buying based on mythology — BatMeckley: “What I was convinced a Fairchild did, and what it actually does were two very different things.” The gap between the Fairchild’s reputation and its day-to-day utility is significant.
• Expecting it to transform vocals — BatMeckley has removed it from vocal chains every single time he has used one. The compression behavior is not always what engineers imagine from plugin emulations and forum descriptions.
• Overpaying for diminishing returns — cian riordan’s spending hierarchy puts the Fairchild last: “If I had $10k I’d probably double up on some of the previous [Distressor, BG2, 1176] before buying an UnFairchild… it’s a real luxury item… certainly not the most flexible or useful.”
• Confusing clones with originals — Rollmottle: “EVERYBODY’s doing one now, whether it’s hardware or software… the long-standing unobtanium mystique might be wearing off.” The market is saturated with Fairchild-inspired products of varying quality.
• Ignoring tube maintenance — cian riordan’s V1 UnFairchild uses 6BC8 tubes with “finite” lifespan. He keeps “a spare matched set of 8” but acknowledges the unit’s days are limited. Vintage Fairchilds require even more intensive maintenance.
• Falling for marketing hype — Nomograph Mastering provides the most direct warning: “Fairchild/Multiband/U47/LA2A/SSL Busscomp have all been marketed and sold as the Panacea at various points.” The Fairchild is the most extreme example of gear mythology outpacing practical utility.

See Also

• UREI 1176
• Undertone Audio UnFairchild
• Teletronix LA-2A
• Manley Vari-Mu
• Chandler Limited Germanium Compressor

Source Discussions

Discord Source

Channel: gear-talk Date: December 2022 - October 2023 Key contributors: BatMeckley, cian riordan, hyanrarvey, David Fuller, Bryan DiMaio, Nomograph Mastering, peterlabberton, Rollmottle, Josh, CK, Edward Rivera, Rob Domos