Changing tubes on amp?

[wardog]

So the stock power tubes have bit the dust on my blues jr. My question to the forum is, do I just replace the power tubes only or should i replace all the stock tubes?
The power tubes are El84-R (2 of them) and the others are 12ax7a (3 of them, they seem to be fine).

 

[watelessness]

Um, warren, I know you too well. You were just looking for an enabler like me to say "just buy another amp". :creep:

 

[László]

If it's not in fact another amp you need...standard spec EL84s generally wear pretty fast. But preamp tubes last a very long time. Like...decades. So you're good to go if the preamp tubes seem fine just getting another set of EL84s. Chances are the amp is cathode biased, so you don't need to have the amp biased. Just insert the new tubes, and off you go!

 

[wardog]

Um, warren, I know you too well. You were just looking for an enabler like me to say "just buy another amp". :creep:

Ha!!!! No Sir, just want to have my fender blues jr rocking again! But, if I was; what would my man watelessness recommend?

If it's not in fact another amp you need...standard spec EL84s generally wear pretty fast. But preamp tubes last a very long time. Like...decades. So you're good to go if the preamp tubes seem fine just getting another set of EL84s. Chances are the amp is cathode biased, so you don't need to have the amp biased. Just insert the new tubes, and off you go!

This is the first time I have had to touch my amp. The stock stuff lasted for over 3 yrs. I don't gig so this is why. So sounds like I am straight.

 

[watelessness]

Ha!!!! No Sir, just want to have my fender blues jr rocking again! But, if I was; what would my man watelessness recommend?

you need a Dallas...just saying...

 

[garrettb]

If it's not in fact another amp you need...standard spec EL84s generally wear pretty fast. But preamp tubes last a very long time. Like...decades. So you're good to go if the preamp tubes seem fine just getting another set of EL84s. Chances are the amp is cathode biased, so you don't need to have the amp biased. Just insert the new tubes, and off you go!

+1

 

[wardog]

Thanks guys for the help. Replaced EL84 and amp is purring like a cat. The funny part of the experience for me was not realizing the amp sound/power was going. I unknowingly put it of as the instrument cable was going bad.

 

[andy474x]

Tubes can be funny like that... I had a preamp tube go a while back and my signal crackled like crazy when I adjusted my volume pot, but luckily I deduced that it was a tube before I went replacing pots.