Tube Life. CB vs FB

[johngovan]

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.

[shooter]

it must be 20 below zero there also 


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 

[sluckey]

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.

[acheld]

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.   

[kagliostro]

I agree, all is on the Bias Level


Franco

[johngovan]

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. 

[johngovan]

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.

[johngovan]

I agree, all is on the Bias Level


Franco

Thanks Franco.

[pdf64]

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.