FET/RACK Revision D

Fully assembled, calibrated and tested.



Use the drop-down menu to add "Active Stereo Link"

The Blackface

This revision covers the REV B thru E units. Most current reissues are based on this revision. Revisions C-E had a blackface 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.


Case by Hairball Audio
Revision A (v1.14) PCBs designed by mnats 

Black anodized front panel 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 5002 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 pushbutton 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.

Active Stereo Link  

$50.00 Use Drop down menu to add 

Improved Stereo Linking with Active Circuitry

The FET/RACK comes with the traditional RCA stereo link connector used in the classic units. Used in combination with the RCA battery powered Stereo Adaptor, it's a simple way to link two units.

We've always thought the linking could be done a little better. The Purple Audio MC77 has always had a great active link feature. In addition to making great gear, they're awesome guys and agreed to let us sell you the circuit set up for the FET/RACK.

The RCA method links the control voltages AFTER the sidechain, which causes the attack time to be doubled. The active link sums the audio from both units before the sidechain and does not affect attack time. It also eliminates the need for super matched FETs or an external calibration box.

To link two units, connect them using a stereo (TRS) 1/4" cable. You can leave the cable connected at all times. To activate linking, press the ON/OFF button on both units to ON. Press the SEND/RECEIVE button on one unit to SEND and the other unit to RECEIVE.

Set the input, output, attack, release,
ratioon both units to the same settings and adjust the attack and output controls slightly to compensate for small difference in units.

Active link is housed on a single PCB that simply snaps to the main PCB using the supplied connector.  Recommended for intermediate builders.
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