0% up to 48 Months on over 110 Brands!

New & Current Vintage King Card Holders

Shop Our Summer Sale

0% financing up to 48 Months on over 110 Brands!

When you shop now with your Vintage King Credit Card.

Best Seller
$ 10,995 .00
No interest if paid in full within 12 months Learn more
More On Order
This product is in high demand and we are shipping as many orders as we can. Place your order today to be included in the earliest possible shipment. Order now and we'll ship when in stock from one of our three fulfillment centers.



UnderTone Audio UnFairchild 670M II

A painstaking recreation of the classic sound of the legendary circuit
MFR# UnFairchild 670M II

Product Description

The UnderTone Audio UnFairchild - Recreating A Beloved Compressor

Under the banner of UnderTone Audio, famed producer and engineer Eric Valentine (Smash Mouth, Good Charlotte, Queens of the Stone Age, Slash) has released an incredible new compressor, the UnFairchild. As an avid fan of the original Fairchild 670, a tool he has utilized on countless records, Valentine was looking to create a more affordable take on the classic unit that would still deliver its trademark sound. In the UnFairchild, UnderTone and Valentine have created a replica compressor that stays true to the characteristics of the original while also expanding the unit to be more flexible in the modern studio.

Breathing Life Into A Classic Compressor

The Fairchild circuit could be one of the most coveted and time-tested compressors of all time. It has proven its extraordinary universal musicality for over 5 decades on countless genres of music. The beauty of its design is in its simplicity. The audio path, primarily consisting of only 2 transformers and 4 paralleled vari-mu tubes, can provide a gentle smoothing of levels or an explosive, energizing compression that will make any recording leap out of the speakers. The UnderToneAudio UnFairchild is a painstaking recreation of the classic sound of this circuit.

A Fairchild With Flexibility

There are a few limitations of the original Fairchild that UnderTone set out to address. First, they have made careful adjustments to the circuitry that greatly improve the lifespan and reliability of the tubes. Additionally, they have added a whole host of exciting new features that have never before been available on a Fairchild. The UnFairchild sports 6 original preset Time Constants and 4 variable Time Constants (attack and release), MS function, side chain processing, a true bypass, fine adjustment of left/right balance, user adjustable "DC Threshold", and "Feed-Back" vs. "Feed-Forward" functionality. With the UnFairchild, UnderTone made this extraordinary circuit flexible enough to handle pretty much every compression task on any style of music.

Product Specifications

Condition New
Unit Weight 37.4 lb
Tube or Solid State Tube
Channels Dual-Channel
Chassis 19-inch Rack-mount
Rack Spaces 8U
Input Connectors Analog XLR
Output Connectors Analog XLR
Impedance 2.5 kOhms (input); 200 Ohms (output)
Compression Type Fairchild-Style
Tube Complement ECC83, ECC83-S, ECC99, 6386-LGP

Product Reviews

5 out of 5 stars.
Review Count (10)

write a review

What makes this different is its musicality. Plug ins, other cheap vari-mu hardware compressors just don’t hold a candle to this. No matter how I set this it’s musical, not sterile, not mechanical it’s just musical. What can I say? If you haven’t heard this then you don’t know what you are missing!

By Todd U on January 31, 2023

Make it sound better with the unfairchild!

By Thomas R on January 26, 2023

This is the finest compressor ever recreated!!!! Witch now makes it the finest compressor ever!!!!! Makes my mixes silky!!!

By Jeff M on October 31, 2021

One of the most favorite pieces of equipment I own. There is a sound that I can’t get from any other piece of gear.

By Jonathan R on July 12, 2021

FFS it smokes.

By yohami z on March 22, 2021


By Matthew N on November 19, 2020

I have many Manley, vintage Neve, Urei, Ua,Retro, etc etc.
This is my favorite compressor for mix buss or drums for rock music, hands down.

By Michael F on June 14, 2020

Effortless compression when you want it. Just seems to make everything sound “better”. Considering what the UnFairchild does to audio, the cost of an original, and the service and support from VK and UnderTone Audio I feel the price for this is completely justified.

By Peter L on October 24, 2019

Bought and use it.

By William on April 22, 2019

this thing is amazing!

By Chris M on February 12, 2019

* Required Fields

Share Your Opinion

The best gear advice always comes from those who use it the most. That's where you come in! Let the pro audio world hear your voice with a review of the UnderTone Audio UnFairchild 670M II . Once you submit your review, please check your email and verify your address to have it posted.

How do you rate this product?
I would like to thank VK for the wonderful sales assistance, service and prices. This was my first purchase with you and it won't be my last. I only wish I'd discovered you years ago!
Matthew R.
I had two Grammy wins this year - Ray LaMontagne & Carolina Chocolate Drops. Both made with help from Vintage King!
Ryan F.
In almost 20 years in Pro audio buying, never did I receive a unit so well packed and exactly as described. Works flawlessly. The whole process has been so smooth. I will never hesitate to do business with you guys in the future and will recommend you to everyone I know.
Martin C.
This was my first experience buying something from Vintage King (although I surf the "used" categories on the website frequently!), and, despite being on the other side of the world, I had absolutely no trouble and everything went very smoothly.
Phil T.
The speed of delivery exceeded my expectations! I was VERY pleased that my shipment arrived in time for a scheduled vocal tracking session. The packing insured that my order arrived safely. And the sales staff responded quickly to questions regarding the product.
James P.
Thank you so much! Vintage King has been so fair and easy to work with. I can't thank you enough. It feels good to trust such a hefty purchase to folks who are so helpful and knowledgeable. Vintage King is a sound designers dream store.
Noa L.
You guys have excellent customer service and I am excited about the next upgrade I complete on my fifth recording facility. I've been in the studio business for forty plus years. The salesman I worked with at Vintage King was the best of the best. You all rock!
Robby T.
I would recommend Vintage King to any one looking for top-class gear, unbeatable customer service and the best prices on the map!
Jake D.
My experience with Vintage King was excellent. The order was here fast considering it was out of stock. The sales person had SKB send it to me directly and I couldn't have been more pleased.
Michael D.
From the minute I placed my order I was kept well-informed through each step in your process. Even though I was buying a comparatively modest piece of gear, your attention to detail made me feel like I was purchasing a six-figure mixing desk.
Thomas W.
I am a new customer of yours. You guys provided me the absolute best deals in ordering all the equipment to power my brand new recording studio. Your customer service is amazing and i will always deal with you from here on out.
Rob M.
Thanks for your great service and getting this out today. You guys really are the Kings!
Alan B.
Better than expected! Truly impeccable service. Your team was professional, knowledgeable, provided speedy delivery above and beyond standard. Vintage King Audio is definitely my go to for all of my audio and information needs.
James O.