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Hairball Audio FET/500 1176

Hairball Audio FET/500 1176

$699.00 USD

Parts are available -- estimated turnaround time: 2 weeks. For additional information and latest ETAs, send a message to


Rev A

Often referred to as a “Blue Stripe”. These units were the first commercial revision and have a silver panel with a distinctive blue stripe over the VU meter. The signal and line amp are based on the 1108 mic pre and use a FET as the first active component in each amp stage (all other revisions use a bipolar transistor). The gain reduction FET in this model has a unique circuitry around it different from all other models (notably the lack of source resistor). This results in a little more distortion that helps define the “Blue Stripe” sound. This revision also has a slightly lower threshold in comparison to later revisions (about 5db) and more gain in the amplification stages (about 5db) than the Rev D. This revision is rare, limited to less than a 1000 units, and are highly sought after by many engineers and producers.


Rev D

This revision covers the REV B thru E units. Most current reissues are based on this revision. Revisions C-E had a black front panel while the Rev B retained the silver and blue stripe panel. Changes were made to the stage and line amps so a bipolar transistor was used as the first active component. Low noise, or “LN” circuitry, was added to this and all future revisions. Like the Revision A, 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, utilizing a 5002 output transformer. This is widely considered to be the most classic FET compressor sound.


Rev F

This unit was offered in a black panel and a silver front panel similar to the Revision A but without a blue stripe. The major change to the revision F was the redesign of the output stage from class A to a 1109 style class AB “push/pull” output, utilizing a B11148 output transformer to provide more gain. Like the Rev A and D the input uses an O-12 transformer and the signal is attenuated at the input with a 600Ω T-pad. We believe the Revisions F is highly underrated and when given a 2:1 ratio becomes one of the more usable compressors we’ve heard.

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