Do power tubes wear out gradually?

uriah1

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Look for old telefunken or Mullard ads from 50s. They listed hours.
 

elet ekim

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I’ve had the same power tubes in my BFDR for about 8 yrs now (about half of that time, 2 to 3 gigs a week) with no trouble. As per my amp tech’s advice, I always run a fan when it’s on. It seems to work imho.
 

arlum

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When it comes to lifespan NOS rules. I use both NOS and new production. I have amps with NOS output tubes going on 8 to 10 years old that sound wonderful. I tend to replace modern output tubes every 2 to 3 years. Then again .... the difference in price might make it worth it.
 

Bartholomew3

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Yup, and with the right tube tester you can watch it happen over time.

Same experience here from the Sixties when a couple of retail stores had tube testers we could walk in and use.

Could see it on the meter as the tubes lost it over the months. Still have a couple of vintage original 12AX7 from back then that work well but had to change 6L6 power tubes every two years approx.
 

oldunc

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Back in the day when TVs had tubes there used to be tube testers in grocery stores and such places, and tube testing was regular maintenance. I distinctly remember my father grumping about it, but I thought it was kind of neat; I suspected that the tester was actually a cleverly disguised robot from outer space.
 

Old Deaf Roadie

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All vacuum tubes wear out over time, except for the ones that just suddenly give up the ghost. The trick is trying to figure out whether the tube simply died or the amp killed it.
 

Henry Mars

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unless they fail all at once, a power tube will degrade over time. NOS pwr tubes like RCA, Phillips etc will generally out last current production tubes by far and will degrade at a slower rate. After a year or two of hard playing on current production tubes you will notice an immediate difference if you replace them. I have old tube amps with old tubes and they still perform well. I have to replace current production pwr tubes in my everyday amps once a year .... especially the 6V6's for some reason.
Given my age and the miserable performance of my body and current production tube amps, I am really looking s SS again. The sound of a lot of SS amps is getting close to tube territory and I'm sick of hving tube mps crap out on me at the worst possible time. Back in the day you didn't worry about it .... these days I carry a spare amp and tubes.
 

TC 57

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Varies greatly. 6V6s in a Deluxe Reverb used constantly would last maybe a year or two.

In a Princeton Reverb used sparingly they could last years, decades. PRs run tubes much more lightly due to lower current draw. Ditto in a Custom 57 Deluxe or 5F1 Champ. The 5F1 might use it's tube slower than the new Vibrochamp as it runs lower voltage.

Preamp tubes similarly could last decades.

Fender Reverb tends to be hard on the 12AT7 driver tube which should still last years, but other preamp tubes could last decades

does it depend on how loud you play? if you play in a studio or at home chances are volume never goes above 10 am on dial..must make a difference..and pre amps must last longer. It has been said tubes from the 60s were made much tougher
 

Dacious

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does it depend on how loud you play? if you play in a studio or at home chances are volume never goes above 10 am on dial..must make a difference..and pre amps must last longer. It has been said tubes from the 60s were made much tougher

Absolutely. If you crank and use a drive pedal it definitely wears tubes out faster than an amp played at low volume and clean..
 

TC 57

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Absolutely. If you crank and use a drive pedal it definitely wears tubes out faster than an amp played at low volume and clean..
in the case of a single channel amp with master, off stage at lower volumes, that means cranking up the pre amp and lowering the volume..so then pre amps get hit harder..it's still difficult to know when a tube is just past it's best..
 

CCK1

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Tubes do wear out gradually, they also fail instantly. I was once hit in the leg, (I was wearing cargo shorts) by flying glass from a YBA-3A Traynor Super Custom Special when one of the 6KG6A power tubes, the ones with the "spark plug wire" on the top decided it had had enough. The only time I'd gotten to get a good look at the inside of a 6KG6A:)
 




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