Setting bias on fender bassman

I just received a pair of matched power tubes from Mojo. Do I need to adjust the bias on my amp (Fender 63 Bassman 6g6 circuit)? I do not have a dedicated bias meter, so could I possibly use my Fluke multimeter? If this is possible where should I hook my terminals to?

Don't the old Bassmans have fixed bias? I always heard that, plus Marshamps says this about their "clone":

Quote :

The Bassman 6G6B!!!

A.K.A. The Blonde Bassman, This is the a Solid State Rectifed 6G6B 1963 Bassman Model. It is a great Blues and Rockabilly, Classic Rock amp for Bass or Guitar!!! 50Watts of balanced awesome tone!!! True to the original circuit, but with an adjustable Bias pot!!! These are Built to order as all our replicas!!! All high quality Vintage style components throughout!!!

(Uh-oh, I just revealed that I've never had the bias adjusted on my Bassman.... )
Anders

Fixed bias just means that the darn amp has a fixed resistor instead of a pot(variable resistor potentiometer). Anytime you change tubes in an amp it has to be rebiased for optimum performance... both for tube life and best tone & dynamics. I know you have heard it before but its truly dangerous fooling inside an amp chassis and accidentally discharging a filter cap through your heart by touching the wrong terminal and ground could release some 400volts DC current into you = death!! So....... please please read this page before you poke the old dmm or fluke mm inside the chassis: amp BIAS FAQ page its a great how to do it in simple terms.

tvthewiredturtle wrote:

Fixed bias just means that the darn amp has a fixed resistor instead of a pot(variable resistor potentiometer). Anytime you change tubes in an amp it has to be rebiased for optimum performance... both for tube life and best tone & dynamics. I know you have heard it before but its truly dangerous fooling inside an amp chassis and accidentally discharging a filter cap through your heart by touching the wrong terminal and ground could release some 400volts DC current into you = death!! So....... please please read this page before you poke the old dmm or fluke mm inside the chassis: amp BIAS FAQ page its a great how to do it in simple terms.

Your right not worth taking a chance. I am having my amp tech do it.

Bobby Retro wrote:

tvthewiredturtle wrote:

Fixed bias just means that the darn amp has a fixed resistor instead of a pot(variable resistor potentiometer). Anytime you change tubes in an amp it has to be rebiased for optimum performance... both for tube life and best tone & dynamics. I know you have heard it before but its truly dangerous fooling inside an amp chassis and accidentally discharging a filter cap through your heart by touching the wrong terminal and ground could release some 400volts DC current into you = death!! So....... please please read this page before you poke the old dmm or fluke mm inside the chassis: amp BIAS FAQ page its a great how to do it in simple terms.

Your right not worth taking a chance. I am having my amp tech do it.

btw... he's gonna want to set it to "exact" oem fender parameters..but if its plate voltage is run just a smidge up, you'll get more transformer saturation which is really what sets the blonde bassman apart from the more heavy duty blackface that is pure girth.(my fender amp guy suggests it but sez' this wears the tubes out sooner btw) The 6L6wgb's and tungsol 5881's along with the tad small bottles have about 5 watts less power than the larger 6L6 GC and this again translates to sooner clipping in the upper mids.. which is why setzer likes
em.