Can you tell by looking at tubes if they need replaced (PICS)

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metalj

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I thought this would be a good learning Thread for those of us that dont know basics of guitar amp tubes.

Can you tell by looking at them when they are on?

notice my picture. All the tubes are burning differentely. Some are glowing bigger, some are dimmer. The first power tube in the back left burns a little on top but not at the bottom as the one to its right.

Is that any question for concern ??

Thoughts. Just wondering

By the way I have this amp for sale if anyone is interested.

I attached a small picture for the thread,but if you really want to look close on a huge pic click here. http://metaljohnson.com/page933.html

Thanks
 

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you really cant make too much of a tube visually... other than it needs to have a heater voltage... which is the glow from the bottom .... or if they are cherry red they are burning up....(or need very badly to be rebiased on outputs)
 
Your best bet is yo take the amp to a reliable repair shop and have the tubes tested. Some tubes opperate a lot "hotter" than others so they will glow more, so just looking dosen't tell you much. Other parts in the circuitry can also cause tubes to run too hot or not hot enough so if you have any doubts get it checked. I recomend taking a tube amp in for a "check up" at least once a year, they will last a lot longer if you take care of them. An increase in hum or fluctuations in volume are good indications that one or more tubes need to be replaced. Clean the sockets and the tube pins occasionaly too, a spritz with contact cleaner is all it takes to do this. And make sure the tubes fit snugly in the sockets, they will viberate loose occasionaly, or get shook loose if you move the amp around a lot.
 
Were they matched to bigin with? One tube may have aged/worn faster than the others but you can't really tell without testing them. Visuals unless something extreme going on like an eminent failure/meltdown or heater going bad don't tell much. If it's collector glow and it's significantly more than the others, I'd pluck them and have them tested.
 
What's the name of that online place where you can buy retube kits for specific amps? I thought it was eurotubes, but I couldn't find it. I have a little cash and was going to splurge for the kit for my PV classic 20. IT has tubes that sound like shit because at least one is microphonic. No coolness at all to that kind of mojo.
 
Sorry. I found it. I guess the page hadn't loaded correctly. It is eurotubes
 
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