Fender Dual Showman Reverb Gold Pin Option

These amps are one of the rare Fender amps that are fixed bias so the only way you can adjust it is to replace the final bias resistor with a value that gets the bias where you want it. This is why most players will simple mod it or have it modded to be adjustable bias.

If your amp is bias modded then all you need to adjust the bias is a bias probe and a multimeter or the Eurotubes "Pro One". All of these are available in the "Related Products" tab.

The video below explains the difference between bias probe types.