Fender Showman & Dual Showman Gold Pin Option

 There were two models of these amps made, the AA864 is fully adjustable bias where the AB165 amps are not fully adjustable, they have a balance circuit where one pair of power tubes is adjustable. With this setup all you can do is match the bias of the adjustable bias sockets, to the fixed sockets. This can be done using a bias probe and a multimeter or one of our "Pro One" bias probes.

All of these are are available in the "Related Products" tab. 

The best solution with these amps is to mod the bias supply to be fully adjustable. Over the years many techs have been doing this by default. If your amp has been modified you can use the Deluxe Reverb bias video for reference. We typically bias these amps between 35 to 40mA with the JJ 6L6GC's or 33 to 40mA for 5881's.