Question about tube amps

[Wasnex]

I have a 1978 Ampeg B-15S with the original power tubes in it and have a 67 Fender Bassman that had the original power tubes in it when I first got it, one of them was microphonic though so I had to put a couple of other 6L6's I had lying around.

Yep, sometimes a tube might start making noise like popping or sputtering. Sometimes the bias will drift so you can't get a good current match with the other tubes. Sometimes a tube may arc and pull fuse. Sometimes a tube may stop conducting. Sometimes a set of tubes may bias up fine, but sound weak and nasty. I probably missed something, but hopefully you get the idea: Tubes can fail in many ways.

I still don't advocate for buying a spare set of output tubes due to the warranty issue. IMHO, if you're going to buy a spare set, put them in the amp to make sure they are good, and keep the old tubes as the spares.

Of course if you're a road dog, that's a different matter. At a certain level, a road dog would probably carry a spare amp. A high level tour would have an amp tech as well.

 

[bobyoung53]

Yep, sometimes a tube might start making noise like popping or sputtering. Sometimes the bias will drift so you can't get a good current match with the other tubes. Sometimes a tube may arc and pull fuse. Sometimes a tube may stop conducting. Sometimes a set of tubes may bias up fine, but sound weak and nasty. I probably missed something, but hopefully you get the idea: Tubes can fail in many ways.

I still don't advocate for buying a spare set of output tubes due to the warranty issue. IMHO, if you're going to buy a spare set, put them in the amp to make sure they are good, and keep the old tubes as the spares.

Of course if you're a road dog, that's a different matter. At a certain level, a road dog would probably carry a spare amp. A high level tour would have an amp tech as well.

I was never a real road dog but did used to play quite a bit and started carrying a spare SVT head around with me for a while but after a while I realized SVT heads won't fail as long as they're maintained so I stopped taking the extra one. The Fender just kind of made a rattling sound when i played through it and the tube also made noise when tapped, you don't often see a microphonic power tube, or at least I don't. Hey I still haven't been home to finish that Blue Line, the airports are closed out here right now, but honestly I think it's a lot safer out here anyway. This country is just about closed, pharmacies and supermarkets are open and pretty much nothing else, no private cars allowed, very few people are out in the streets, we have to wear masks etc, only one person can go out at a time, they take it very seriously out here, if you get caught playing around they fine you.

 

[Wasnex]

I was never a real road dog but did used to play quite a bit and started carrying a spare SVT head around with me for a while but after a while I realized SVT heads won't fail as long as they're maintained so I stopped taking the extra one.

That's hard core. The only way I would carry two SVT is if we had truck with a lift gate and the amps were package rolling shock mount case:

 

[bobyoung53]

That's hard core. The only way I would carry two SVT is if we had truck with a lift gate and the amps were package rolling shock mount case:
View attachment 3819544

This thing makes it easy but yes I did get sick of lugging both of them, years ago I used to use two of them, haha!:

 

[Ric Vice]

It's never a bad idea to have spare ones. But the answer to "how often" is "when it goes bad." I miss the days when you could find a tube-testing machine in most dime stores (I guess those are gone too), drugstores, and hardware stores.

Those were the days my friend. Dale Hardware had one I used many times.

 

[penllyn]

How often do you need to replace all the tubes? Does the amp eventually start to sound bad? Should I get a backup set?

My late 70's fender studio bass combo is still using all the original factory fit preamp valves. Gigged about three times a week, studio work in between, for over two decades in my ownership. The power valves (6x6l6gc) changed near enough every year, J.Js seem the best of the bunch to me.

 

[agedhorse]

Somebody has a big stash of likely good power amp tubes, hope you saved them all.

 

[BogeyBass]

Man, some of you guys have good luck. When I was touring, even with a custom fit foam lined hard case, I would often have at least one tube bite the dust annually or semi annually. And this is on a series of SVT's from different eras and a new-ish Orange.
A lot of it is temperature I suspect. Burning hot all night, goes into the case hot as hell, then out to the cold trailer for a bouncy drive for 2 to 14 hours.

Lol Exactly

I love it when they say tubes last 10 to 20 years
I mean they can, but not on tour

more like 10 to 200 miles
or 2 to 5 gigs

Using 2 SVTs at once, that quickly stopped to using one and keeping the other as back up.
then a 3rd.

Because you literally need a back up for your backup and then a backup for that backup

Because when your back up is being repaired you still need a back up lol

 

[beans-on-toast]

If you drive your car with the brakes on, you'll wear them down quickly. Push tubes hard and they won't last as long. But tube life also depends on the amp's design.

I once owned an amp that sounded fantastic with new preamp tubes for the first month or so, then it would loose some of the sparkle that made it sound so good. The difference was really noticeable, the amp ate tubes for lunch. The problem is, for consistancy when recording, you want it to sound the same. So they kept a box of tubes on hand. This is the reason why I sold it. A kid in a metal band bought it, cranked all the way up and distorted was good for their style of music.