Fender Blues Jr Bias Kit

Fender Blues Junior amps have one major design flaw. They use a non adjustable grid bias in the power stage, and it’s set far too high. W’ve seen as high as 130% idle bias on units straight out of the factory. It’s no wonder so many of them can  eventuallycarbonise the pcb.  Some examples run the EL84 output valves at 130% of full power. The valve pcb is slowly cooked and the EL84’s life is greatly shortened. This kit ensures maximum EL84 output valve life AND ensures that the main pcb does not get cooked.  There is a solution with the Fender Blues Jr Bias Kit.

This is an easy to fit kit which adds fully adjustable bias to your Fender Blues Jr.

This Blues Junior Bias mod kit is designed so that in the unlikely event of the pot wiper going open circuit, the power valves grids swing negative, saving the valves. Much of the advice on the internet about doing this mod misses this critical point  – other  mods will leave the grid floating up towards GND in the event of pot oxidation, which will destroy the power valves.

We have partnered with Keld Ampworks to offer this simple to fit kit.

If you are buying this kit, then you should probably at a minimum replace your EL84 ‘s as they are probably worn, especially if they have been under biased.

You will  see a few options on complete valve kits during the check out process, JJ, and Sovtek including a kit with the mighty bombproof Sovtek EL84M’s.

Click here to see our Fender Blues Jr valve kit options with medium and full gain valves

Check out this YouTube Video  and see how to fit this board.  Super simple. You can also click here to download the installation instructions and see how it is done

Fitting just consists of snipping out two resistors and a bit of glue to hold the little board down. We work in partnership with Keld Ampworks.

In stock  ! We ship six days a week and same day if ordered before 2.30pm on weekdays and 10.30am on Saturdays.