Compressor
UnFairchild 670M II
The legendary Fairchild 670, rebuilt for the records you make now.
The original Fairchild 670 shaped more hit records than any compressor ever built. Sixty years later, originals are museum pieces with museum problems: scarce tubes, drifting components, and six-figure auction prices.
The UnFairchild 670M II is Undertone Audio’s answer. It delivers the variable-mu character of the original and then goes where the original never could: four additional variable time constants, feed-forward compression, full M/S operation with independent control, external sidechain access, and a DC threshold control. It is the Fairchild you always wanted, built to work every day.
Know the Panel
Every control, explained.
Per-channel meters that switch between level and gain reduction. Watch the needle breathe with the program.
BYP, VU, GR, and BAL modes per channel, with gain trim and GR zero trims underneath.
Stepped input gain driving the vari-mu stage. How hard you hit it is half the sound.
Sets where compression begins for each channel.
The six classic Fairchild presets plus VAR positions that hand you the four variable settings.
Switch between L/R and M/S operation, with channels linked or fully independent.
The lower panel dials the four variable time constants by hand, per channel.
Fine threshold control for each channel, beyond anything the original offered.
- VU Meters Per-channel meters that switch between level and gain reduction. Watch the needle breathe with the program.
- Bypass - Bal BYP, VU, GR, and BAL modes per channel, with gain trim and GR zero trims underneath.
- Input Gain Stepped input gain driving the vari-mu stage. How hard you hit it is half the sound.
- Threshold Sets where compression begins for each channel.
- Time Constant The six classic Fairchild presets plus VAR positions that hand you the four variable settings.
- M-S Link Switch between L/R and M/S operation, with channels linked or fully independent.
- Variable Attack and Release The lower panel dials the four variable time constants by hand, per channel.
- DC Thresholds Fine threshold control for each channel, beyond anything the original offered.
Listen
The only spec that matters.
Hear it. UnFairchild, in and out of the chain.
Demo audio coming soon.
Demo audio coming soon.
Demo audio coming soon.
On Real Records
"Unfairchild is by far the best compressor I own. Worth its weight in gold. Amazing!!"
"The 670M II gives me a broader sonic palette and more flexibility than the vintage units."
"I wanted a Fairchild for years. Everything I wanted from a Fairchild and more."
Under the Hood
| Type | Stereo variable-mu tube compressor |
|---|---|
| Tube complement | 20 tubes, including eight 6386 vari-mu tubes |
| Transformers | 14, with Cinemag recreations of the originals in the audio path |
| Audio path | 2 transformers and 4 paralleled vari-mu tubes |
| Time constants | 6 preset + 4 variable |
| Compression modes | Feedback / Feed-forward |
| Operating modes | Left/Right, Mid/Side |
| Sidechain | External input |
| Bypass | True bypass |
| Rack size | 7U |
| Weight | 65 lb |
Questions, answered
How is the UnFairchild different from an original Fairchild 670?
It keeps the variable-mu tube compression character of the original and adds capabilities the original never had: four variable time constants on top of the six classic presets, a feed-forward compression mode, full M/S operation, external sidechain access, and a DC threshold control. It is also built with modern, serviceable components and backed by a two-year warranty.
Can it run in Mid/Side mode?
Yes. The UnFairchild operates in Left/Right or Mid/Side with independent control of each channel, which makes it a powerful mastering tool as well as a tracking and mix bus compressor.
What is the warranty on the tubes?
The unit carries a two-year warranty on parts and workmanship. The JJ Electronic tubes are warranted for six months. A tube replacement guide is included in the downloads.
Where can I buy one?
The UnFairchild is sold through authorized Undertone Audio dealers worldwide, including Vintage King, Alto Music, and Sonic Circus in the US. See the dealers page for the full list by region.
Is there a plug-in version?
Yes. The UTA-D UnFairchild 670M mkII plug-in was built with MIXLAND and Eric Valentine, costs $149, and comes with a 14-day free trial. It also adds a wet/dry mix and an overall THD control.
Goes Well With
Hear it in your own session
The UnFairchild plug-in is $149 with a 14-day free trial. The hardware is at a dealer near you.