How often do you change power amp tubes? Some say they use them for decades?

personally, i don't change them very often. I generally just go by my ears. It helps that I have a couple similar amps, so I can better tell when a tube may be starting to fade a bit... Although I do know people that change tubes every year or so, I go several years before I change tubes. I'm talking power tubes. Most of my preamp tubes have been in use snce the 60's. Quality tubes can last a lonnnnnnng time. I think it also might help that I use heads rather than combos, so much less vibration on the tubes (?)

 

It all depends. I've had the same set of Winged C EL34s in my Rivera for about 5 yrs or so. I'll probably replace them soon, but not because I need to.

 

I think it's more a "go by ear" thing, too. If the amp gets banged around a lot moving, it's more likely the tubes will go microphonic and you can always hear that. Also, amps that are physically abused may end up with tubes that have broken elements in them. They'll stop working, so you can definitely hear that. Finally, the filaments can burn out or the tube can get so gassy it doesn't conduct worth a damn any more, but those two things are less common, and are also audible.

With tube amps, if it ain't broke, don't fix it. It's as likely to run for 10 years as a week.

 

The RCA blackplates that I swapped out a few months ago were the ones that came with my amp, in 1958. They still sound fantastic, just started to get a little flabby in the bass register...

 

The old tubes are much, much better. The new companies just don't care because there are no military contracts on the line. The US army isn't testing their tubes.

 

The man at Victoria said to expect about 5000 hours from power tubes. I think he was refering to modern tubes.

 

I’m the original owner of my 1965 Super Reverb and 1968 Twin Reverb. Both amps have RCA Blackplates installed. The ones in the Super are the original tubes that came with the amp. The Twin had one of the Blackplates replaced about two years when I brought it to my amp tech for a cap job. Both amps sound terrific. Making vacuum tubes is both an engineering discipline and an art form. In my opinion the modern manufacturers of tubes have not mastered either of these aspects.

FVB

 

Completely depends on the amp, the plate voltage, the bias current, the load impedance, tube manufacturer, the hours of use, the on/off cycles, whether it's a head or combo, and how often the amp is moved/banged around. Age in years is almost irrelevant compared to everything else.

 

I'll generally leave the NOS stuff in indefinitely, unless I suspect something's not right. But, I just bought an amp that had JAN Philips 6L6WGB's installed and thought it sounded muddier then it should. I checked the bias and it was fine. Then I popped in some =C= 6L6GC's and the difference was amazing! Much, much clearer, more alive, tighter. It was like taking a blanket off the amp.

So lesson learned for me - it's always worth doing an A/B check against some known, strong tubes to make sure your NOS stuff is sounding right to begin with.

 

I have bought a number of older Traynor amps from the mid-sixties to early seventies. Some of them had the original power tubes, which were Philips-rebranded Mullards. Some of them tested as-new. The stock pre-amp tubes [again, rebranded Mullards - either Philips or Rogers] almost ALL tested perfect after all those years.

 

To the OP - whoever told you to change them every 6 months is tripping. I've had nice NOS tubes in all my Fenders; I've owned them for years and still haven't changed out the tubes.
Take good care of the amp - the tubes won't last forever but they will last a long time.

 

Just changed out the RCA 6V6GTAs in my 68 PR the other day (for another set of RCAs). They were run pretty damned hard for eight years.

 

I have often changed amps before I ever remotely needed to change power tubes

Things have settled down in my amp buying and I average 2-7 years on my power tubes. I know that is a huge range, but I find it varies that much between amps and how much I use them.

Generally when I hear a power tube going it is crackling, loss of bass, and dull sounding. I like to get as much life as I can from my power tubes, same with strings. Others like to change both on a fixed interval. Do whatever makes you comfortable...

 

more anecdotal evidence...

I bought my Vox Berkeley in 1971 or-so. My dad was a technician, so we tested the original Vox-labeled tubes. They were working, but new Sylvania tubes tested better, and I replaced them, keeping the Vox tubes.

I used that amp a lot at first, carted it around three states over the intervening decades, using it sporadically and storing it under various (not always ideal) conditions. Now, I use it a lot for recording and I'm very happy I kept it all these years.

I just had this restored a few months ago (thanks Billy Yates at Venice Amplifier!). We evaluated the tubes, and found that the Sylvanias still work great and had a little more breakup at lower levels than the Vox tubes, so we kept them.

My guess is that if a tube is broken, you'll know, and you'll replace it. Otherwise, if you're happy with the sound, keep it.

 

change when the sound suffers

 

the 6 mo's to a year time frame, that I've heard before, seems like the "change the oil in your car every 3000 miles" bit. Meaning, no it can't hurt but it's a little overkill.

 

How often do you change your strings? Some guys change em every week and others don't touch em until they either break or they don't tune up anymore.

It's the same idea with tubes. Some people seem to think that the lifespan of a tube is over when it stops functioning while others change em as soon as they don't sound the same as the day they were fired up.
Also every tube type and manufacture as well as amp conditions all effect tube life.

In general though preamp tubes last longer than power tubes....

 

Most ofter preamp tubes need changing more so the power tubes, usually the first in the chain when you get that crackle or power dip

 

My this is the solution to technical problems I've adopted. it now applies to tubes....