FET/RACK Revision F
Complete DIY Kit


Message About Price Increases

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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