When to replace tubes?

bri · February 12th, 2005, 12:27 AM

I have a Blues Jr which I bought new in 2000. I use it a lot and wonder about tube replacement. Do you wait until it starts to fail or do you head off trouble and replace them all at once at a certain age? This BJ is my only tube amp so I have no experience to base my decision on. It seems to me I've heard that 5 years is about all you can get out of tubes. Is this right?
Any comments greatly appreciated.
Brian

Wally · February 12th, 2005, 02:38 PM

If you play the amp quite a bit, your power tubes may well be yielding less than optimum sound. I would suggest that you go ahead and have the power tubes and perhaps the driver replaced and note the change in sound. The best way to learn about the 'before and after' of sonic effects of tube/circuit changes is to make a change and take note. If new tubes don't yield a better (firmer, more harmonically rich, more powerful) then either your original tubes were not worn very much or the new tubes aren't very good tubes. The JJ El-84 is a pretty good tube if you decide to retube. Keep the old tubes for emergency backup.
As for waiting for tubes to fail, one can't predict when that might happen, but the degradation of sound should clue you before a tube fails of old age. If one could predict exactly when a tube might fail, one would surely want to avoid putting other components at risk due to a catastrophic failure linked to a tube failure.

TexGoneNW · February 12th, 2005, 04:35 PM

I used tube amps until tubes were checked for the heck of it and tested bad. Maybe I'm lucky, but:

I've never had a tube fail causing catastrophic damage.

I've had tubes work their way out of the socket so I was only using one power tube of the pair in a Pro Jr., and just turned it off & made sure not to burn my fingers when pushing it back in.

YMMV

Tubes tend to degrade over time if they have any time on them at all. I suspect some bad ones fail early in the life cycle, though.

Daddy Elmis · February 12th, 2005, 05:37 PM

First, I'd have a full set of spare tubes in my gig bag at all times. If you think any of your tubes are going, you can test it out by swapping tubes.

Preamp tubes last a really, really long time unless they have a mechanical failure (then they'll either burnout or get microphonic). Power tubes can degrade over time, but more often just quit. The bias of the amp can drift over time yielding different plate voltages.

February 12th, 2005, 12:27 AM	#1 (permalink)
bri Tele-Meister Join Date: Mar 2003 Location: Ontario, Canada Age: 68 Posts: 455	When to replace tubes? I have a Blues Jr which I bought new in 2000. I use it a lot and wonder about tube replacement. Do you wait until it starts to fail or do you head off trouble and replace them all at once at a certain age? This BJ is my only tube amp so I have no experience to base my decision on. It seems to me I've heard that 5 years is about all you can get out of tubes. Is this right? Any comments greatly appreciated. Brian

February 12th, 2005, 04:35 PM	#3 (permalink)
TexGoneNW Tele-Holic Join Date: Mar 2003 Location: Victoria, TX Posts: 917 4 Photos	My .02 I used tube amps until tubes were checked for the heck of it and tested bad. Maybe I'm lucky, but: I've never had a tube fail causing catastrophic damage. I've had tubes work their way out of the socket so I was only using one power tube of the pair in a Pro Jr., and just turned it off & made sure not to burn my fingers when pushing it back in. YMMV Tubes tend to degrade over time if they have any time on them at all. I suspect some bad ones fail early in the life cycle, though.

February 12th, 2005, 02:38 PM	#2 (permalink)
Wally Friend of Leo's Join Date: Mar 2003 Location: Lubbock, TX Posts: 4,212	If you play the amp quite a bit, your power tubes may well be yielding less than optimum sound. I would suggest that you go ahead and have the power tubes and perhaps the driver replaced and note the change in sound. The best way to learn about the 'before and after' of sonic effects of tube/circuit changes is to make a change and take note. If new tubes don't yield a better (firmer, more harmonically rich, more powerful) then either your original tubes were not worn very much or the new tubes aren't very good tubes. The JJ El-84 is a pretty good tube if you decide to retube. Keep the old tubes for emergency backup. As for waiting for tubes to fail, one can't predict when that might happen, but the degradation of sound should clue you before a tube fails of old age. If one could predict exactly when a tube might fail, one would surely want to avoid putting other components at risk due to a catastrophic failure linked to a tube failure.

February 12th, 2005, 05:37 PM	#4 (permalink)
Daddy Elmis Tele-Holic Join Date: Jun 2004 Location: USA Posts: 961	First, I'd have a full set of spare tubes in my gig bag at all times. If you think any of your tubes are going, you can test it out by swapping tubes. Preamp tubes last a really, really long time unless they have a mechanical failure (then they'll either burnout or get microphonic). Power tubes can degrade over time, but more often just quit. The bias of the amp can drift over time yielding different plate voltages.