Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: johngovan on December 23, 2022, 08:59:40 am
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Which bias will give tubes a longer life? Given the amp is used only 8 hours twice a week?
For example a fender deluxe reverb being a fixed bias vs. tweed deluxe being a cathode bias.
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it must be 20 below zero there also :icon_biggrin:
guitar players want amps with guitar sounds, if that means new PA's every year, cost of sounding good
corksniffers want, well, they don't know what they want, there's no consensus :icon_biggrin:
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Which bias will give tubes a longer life? Given the amp is used only 8 hours twice a week?
For example a fender deluxe reverb being a fixed bias vs. tweed deluxe being a cathode bias.
The deluxe reverb gets to idle and take a break when you are not playing. The tweed deluxe is always running pedal to the metal.
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It also depends on the bias level.
Example: Blues Juniors I-III were fixed bias, but were biased hot from the factory, and their EL-84s suffered for it. Whereas, the BJ IV is now cathode biased with a "reference book" Rk of 270R (per tube), and I have not heard of early tube failure on forums.
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I agree, all is on the Bias Level
Franco
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Which bias will give tubes a longer life? Given the amp is used only 8 hours twice a week?
For example a fender deluxe reverb being a fixed bias vs. tweed deluxe being a cathode bias.
The deluxe reverb gets to idle and take a break when you are not playing. The tweed deluxe is always running pedal to the metal.
Thanks Steve for help. Really appreciate it.
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It also depends on the bias level.
Example: Blues Juniors I-III were fixed bias, but were biased hot from the factory, and their EL-84s suffered for it. Whereas, the BJ IV is now cathode biased with a "reference book" Rk of 270R (per tube), and I have not heard of early tube failure on forums.
Thanks a lot acheld. So it all depends on how hot or cold the amp is biased.
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I agree, all is on the Bias Level
Franco
Thanks Franco.
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I think it also is affected by the amp design, especially peak dissipation of anode and screen grid, combined with how hard it gets used.
eg 8 hours of coffee shop jazz is easier on the valves than 8 hours cranked up overdriven.