FET/RACK Revision F
Complete DIY Kit

$650.00

January 3rd 2026 Stock Update: We are currently out of input transformers for this product. We will have more at the end of January but are working to get more sooner. Please check back.

The Red Stripe

Traditionally, the Revision F has a black faceplate and looks just like the Revision D.  In many cases, original units are confused for Rev C/D/E's with engineers mistakenly thinking of the revision F as a silver faced unit. To give this underrated revision a unique look, we've added a red stripe and red off button cap. Though the Revision F is cleaner than the A or D, it's not dull or boring. In fact, it's the favorite of many at Hairball Audio. It imparts that classic FET compression while adding a glossy, polished sound to the source material. Frankly, it makes everything sound like a better version of itself. A favorite of top engineers, including Bruce Swedien, this is a flavor unique to the predecessors. Like the Revision A and D, the input uses an O-12 transformer and the signal is attenuated at the input with a 600Ω T-pad. The output is class A/B, utilizing a B11184 output transformer. 

Interested in a FET/RACK but not into DIY? Check out our list of kit builders.

Recommended for intermediate builders.
  • All the parts needed to complete the build
  • Revision F (v1.12) PCBs designed by MNATS 
  • Black anodized front panel with red stripe made in Seattle, USA
  • Custom 18 gauge steel zinc plated enclosure made in Seattle, USA
  • Custom Ed Anderson O-12 reproduction input transformer made in the USA
  • Custom Ed Anderson B11148 reproduction output transformer made in the USA
  • Custom Ed Anderson 11754 reproduction power transformer made in the USA
  • Custom BI Technologies T-Pad input attenuator
  • Interlocking push button switches with “All Buttons In” mode
  • Fully discrete audio path including capacitors selected by ear from Kemet, Nichicon, Panasonic, Vishay, United Chemi-Con and Elna
  • Bourns trim pots
  • Neutrik XLR connectors
  • JST connectors and pre-assembled wire harnesses
  • 120/240 voltage select switch
  • 1% metal film resistors
  • Matched FETs
  • Authentic control knobs

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