Question from a tube noob

[ef_in_fla]

I just bought a twin tube OD pedal that is about 7 years old. It still has the orig 12ax7 Mesa tubes in it. I'm wondering if they're getting toward their end of life and do I need to think about getting them replaced? How long do these preamp tubes last anyway? Thanks.....

[m-theory]

I've still got the original tube in a Chandler tube driver that I bought new in the mid-80's, I know for a FACT that it's completely worn out, but it sounds far better than any new tube I've tried, regardless of brand, production year, or part number. Don't ask me why. If you asked those who're "in the know" regarding that circuit, they'll tell you emphatically that the tube has nothing whatsoever to do with the tone. But, I know differently, because I've done more than my share of swapping.

 

The point is, yeah, the tubes might be worn out. Or, they might not be. Only a tube tester could tell you that for certain. However, a worn tube in a device such as this may or may not cause a degradation of tone.

 

I suspect, though do not know for certain, that your pedal is of "starved plate" design, similar to the tube driver, where very low voltage is run across the tube, rather than amp level juice. Thinking logically, a tube run in such a mild manner should conceiveably last virtually forever, but, as I've found myself, that isn't necessarily so. Actually, I wouldn't be the least bit surprised if the tube in my TD was worn from the very day it was built.

[layboomo]

I've still got the original tube in a Chandler tube driver that I bought new in the mid-80's' date=' I know for a FACT that it's completely worn out, but it sounds far better than any new tube I've tried, regardless of brand, production year, or part number. Don't ask me why. If you asked those who're "in the know" regarding that circuit, they'll tell you emphatically that the tube has nothing whatsoever to do with the tone. But, I know differently, because I've done more than my share of swapping.

 

The point is, yeah, the tubes might be worn out. Or, they might not be. Only a tube tester could tell you that for certain. However, a worn tube in a device such as this may or may not cause a degradation of tone.

 

I suspect, though do not know for certain, that your pedal is of "starved plate" design, similar to the tube driver, where very low voltage is run across the tube, rather than amp level juice. Thinking logically, a tube run in such a mild manner should conceiveably last virtually forever, but, as I've found myself, that isn't necessarily so. Actually, I wouldn't be the least bit surprised if the tube in my TD was worn from the very day it was built.[/quote']

 

I think thats a good perspective.....often with pedals and many amps too...it's the bouncing around that kills preamp tubes not voltage and use. FWIW when I had my 67 BF fender gone through by a highly respected amp builder...he said to leave the original tubes in it because they "souded great and I probably would not be able to improve upon them."

[ef_in_fla]

Thanks guys, I appreciate it!

[MikeRom]

If the tube starts flaking out you will definitly know about it. You won't have to wonder ...

[tonedeaf1281734100]

I agree. I have usually treated preamp tubes like light bulbs. They are good until they stop working (or become microphonic). Power tubes definitely deteriorate in sound quality before they go dead, however.

 

Maybe preamp tubes do the same, but I have never been cursed with "good ears". Helps to be tone deaf.