Do power tubes wear out gradually?

Vibro Chimp

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I recently replaced some power tubes with new ones of the same brand and immediately noticed more treble. Previous tubes had been in there for years so I can’t remember what they sounded like new. Does anyone know if tubes gradually lose tone over time?
 

Dacious

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What would the average lifespan be of a modern tube?
Like in the Fender re-issue amps.

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
 

Dacious

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I've just noticed my 83 Superchamp after a few years of constant gigging on 6npn (old Reflektor 6V6) tubes has lost a lot of oomph. Time to swap.
 

24 track

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What would the average lifespan be of a modern tube?
Like in the Fender re-issue amps.

first off what reissue ?

I have a 65 twin BF RI my cheap chinese no name tubes sucked so I replaced them
I did a repair on the same model amp , I saw so many inconsitencies , bad solder joints , sloppy soldering, cold connections , that i took my own amp apart to see if i had the same issues ,I didnt thank goodness


it depends on the make , type of tube and the condition of the the other components a capacitor is designed to allow A/c current to pass through and block D/C current but when they break down they leak D/C current to the wrong places , this could cause tubes to go bad prematurely also if the grid resisters go bad and over heat this will allow bad voltages to enter , this also burns up tubes faster than normal , a bad biasing will cause tubes to wear down or burn out faster.
some brands of tubes are better than others and are more stable .

so its kind of an ambiguous question

in a well serviced , properly biased amp, tubes may last for years with out issues , and a hard driven amp that is used hard every day maybe not so long .
 

Killing Floor

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Tubes are inconsistent. Even well matched tubes don’t age exactly the same. Just saying there is no magic way to predict how long they will last.
In my industry we use terms for how long a new product will maintain 70% of its designed output. It would be great if tubes had a similar metric so you could do preventative maintenance.
 

mfguitar

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I have heard on more than one occasion that tubes sound best just before they need to be replaced. Beauty is in the eyes of the beholder but I have experienced that as well. Mine have a lot of hours right now but still sound good to me. Always have some spares.
 

Sea Devil

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I have heard on more than one occasion that tubes sound best just before they need to be replaced.

That's usually said in the context of running the tubes really hot, which will fry the tubes quickly but make them sound great (to some ears, anyway).
 

beninma

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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

Some of this stuff is annoying in terms of those amps overdriving tubes. Does a Deluxe really gain anything by burning out tubes that much faster than a Princeton? (Usually we hear this more about the Blues Jr though right?)

It's not about gain.. plenty of newer designs are much gentler on the tubes with massively more gain than older amps.
 

Hey_you

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Zoso420

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Some of this stuff is annoying in terms of those amps overdriving tubes. Does a Deluxe really gain anything by burning out tubes that much faster than a Princeton? (Usually we hear this more about the Blues Jr though right?)

It's not about gain.. plenty of newer designs are much gentler on the tubes with massively more gain than older amps.
There is a difference between pre amp gain and power amp distortion. Ever notice how some 4x 6l6 amps are rated for 100-120 watts and some are as low as 80 watts. How high of voltage and bias settings depends on how hard a power amp tube has to work.
 

Les H

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Some wear out gradually, some wear out suddenly.

I'm mainly an EL84 user and I change mine at least once every 12-15 months as I use my amp regularly for fairly long periods of time.

When I start to notice a loss of brilliance or the clarity starts to fade somewhat or just sounds off the first thing I'll do is put on a fresh set of guitar strings if my current strings are fairly old and if it still sounds on the dull side it's time to order new tubes.
 

Dacious

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Some of this stuff is annoying in terms of those amps overdriving tubes. Does a Deluxe really gain anything by burning out tubes that much faster than a Princeton? (Usually we hear this more about the Blues Jr though right?)

It's not about gain.. plenty of newer designs are much gentler on the tubes with massively more gain than older amps.

No, it's not about overdriving tubes. The Deluxe Reverb puts out somewhere around 20 watts.

The Princeton Reverb puts out 12. They use the same power tubes.

So if you use both in anger the DR will wear tubes out faster. It's plain physics. Power in watts is current by volts. More power means more heat. More volts and current, tube works harder.

If you never turn the DR past 2 the tubes will last longer than if you play it at gig volume.

The PR is intended as a studio amp. The DR is intended as a gigging amp. That's why it's more powerful and it wears tubes faster.
 




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