Fender Bassman - Bandmaster ECC803S Option

1964 thru 1967 Bassman's Known as "Blackface” AA864 is adjustable bias. AA165 & AB165 are balance.

1968 thru 1971 Bassman's Known as "Silverface” AB165 is balance. All others are adjustable bias.

1963 thru 1967 Bandmaster's Known as "Blackface” AB763 is adjustable bias.

1968 thru 1974 Bandmaster's Known as "Silverface”  AB568, AD1269 and AC568 are balance.

If your amp is adjustable bias all you need to bias the amp is a bias probe and a multimeter or the Eurotubes "Pro One" which reads both the plate current and plate voltage simultaneously. All of these are available in the "Related Products" tab. If your amp has the stock "balance" bias circuit we highly recommend modding it to be fully adjustable bias.

You can use the Deluxe Reverb bias video for reference. We typically bias these amps between 36 to 44mA with the JJ 6L6GC's, or 33 to 40mA for 5881's and between 23 to 28mA with the JJ 6V6S's. The bias pot is located inside the chassis.