Triple7
The Decepticon
Thanks for the info, not sure if this is something I can do myself though.
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THis is SO happening to the 6505+ i have this weekend![]()
on the 5150 all you have to do is change the resistor, there's a pot installed on it already it just doesnt get hot enough without the resistor swap.
The Bias for the 6505+ is simply replacing a single resistor with a lower value to shift the existing range of the pot into "hotter" bias territory.Can anyone give me info on these bias mods?
I have a stock 6505+ and heard that one can get even better tones with a bias mod.
What is it exactly?![]()
Voltage will not be increased. At all. I am not even sure what this guy meant by "drive". He probably realizes this now, it's an old thread.The tech will install a pot which will allow you to increase the plate voltage and get more drive from the tubes.
And 35mA is still cold hahahahaIT decreases crossover distortion in the poweramp section. It onoly effects the power tubes. It makes the amp sound a hell of a lot better too. If you take the back plate off the 6505+ and look inside above the ground switch near the power transformer. There is a bias adjustment knob there already. Bias it as hot as it will go, which is WELL within the range of the 6l6s that it has in it. It only goes to like 20-25 mA they should be more around 35mA.
Yes, at 50 mA, as they are rated.So then biasing the amp correctly helps increase the wattage? Would it be possible to get a 6505 closer to the 100 watt mark with proper bias?
Biasing the amp HOT may not be "correct", considering it will chew your tubes up. But it gives some people the sound they're after.......
J
I am at the stage of wandering whether it's really worth increasing the bias in my 6505... I mean, is the difference in sound THAT great? Isn't that just another myth? A local guy who is into amp construction advised me against it. He said that the difference in sound would be negligible, but the tube life woud be considerably shorter...![]()
You mean the 5150 II or the 6505+.on the 5150 all you have to do is change the resistor, there's a pot installed on it already it just doesnt get hot enough without the resistor swap.
Voltage will not be increased. At all. I am not even sure what this guy meant by "drive". He probably realizes this now, it's an old thread.
And 35mA is still cold hahahaha
Yes, at 50 mA, as they are rated.