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SuperFET Jack

The Granger SuperFET Jack is a high gain, MOSFET driven preamp gain stage that operates at high tube voltages. The entire circuit is mounted on a small PCB (1.625" x 0.875") that includes the jack. The level is pre-selectable via internal trim pot that is accessed directly through the jack opening, adjustable from nothing, to "over the top", and has more gain then a single 12AX7 triode stage. The SuperFET Jack stage is wired in series with the other standard gain preamp stages so it can really push them. Analog, tube-like distortion and soft clipping for a great clean boost-to-overdriven tone. Adding the SuperFET Jack can push just about any low gain amp into fabulous overdrive. High sensitivity allows for lower gain by rolling off the guitar volume, just like a tube stage.

The SuperFET Jack has provisions to be wired with a bypass switch (optional, see below), a separate relay for footswitching (available as a separate product), or by simply wiring it direct (via default, on-board jumper) and bypassing it by plugging into another regular input jack. Wiring is as simple as removing one of your amp's jacks, mounting the SuperFET Jack, and running 3 wires: B+ (tapping off the V1 or V2 plate resistor), Ground, and Signal Out (the wire that is connected to the V1 grid at pin 2 or 7). Three sections of 22Ga 600V PVC Topcoat wire are included (Red, Black, Green)

Instructions, with example schematics, are included.

  • Gain level adjustable through the 1/4" jack opening
  • Works on nearly all amps
  • Metal or Plastic Cliff Jack Nut (choose below)
  • Bypass Switching (choose below)
  • Works from 80 to 350Vdc supply voltage
  • Simple 3 wire installation
  • Easily added to any vintage amp
  • Low noise
  • Gain up to 17dB
  • Perfect for many different guitar amps

*Note: All our shipping vendors (USPS, FedEx, UPS) have recently increased their rates for International Shipping. The shipping calculator will charge a fixed price, and we will invoice you any difference before shipping the product.

PRICE: $45 + $7 S/H (US)*
Bypass Switch
Jack Type

Prices subject to change without notice. Orders already in progress are not subject to price changes. Granger Amplification reserves the right to make any product design changes without notice or obligation to incorporate these changes in products previously purchased.

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All content copyright 2007-2013 by Blue Nite Productions. grangeramp.com is the website of Granger Amplification, a company that builds quality, custom amplifiers, one at a time, at very reasonable prices. Our focus is on producing all-tube, hand wired amplifiers based on proven designs such as vintage Marshall and Fender products, and other boutique amps, while charging a fair price. We also do kit building, modification, and repair work. We specialize in Plexi recreations, custom, boutique amp builds, and custom mods. All trademarks are owned by their respective companies and are only used herein for historical references. - guitar amplifier, amplifier, guitar, amp, amps, builder, for sale, fs, repair, mods, hand, wired, tone, custom amp, custom amps, amp mods, ultimate fx loop, modifications, amplifier, handwired, point to point, tube, vacuum tube, valve amp, kit build, amp kits, made in usa, d18, e35, m45, m50, g50, cg50, lead overdrive 100, dragonfly, marshall, fender, jtm50, jmp, jcm, superlead, plexi, 15 watt, 18 watt, 35 watt, 36 watt, 45 watt, 50 watt, 100 watt, single ended, push pull, 5E3, bassman, matchless, trainwreck, express, tweed, deluxe, curt granger, birmingham alabama