Quicky (tube brightness)

[Gibbyage]

I was jamming on my Stiletto Deuce and I noticed the first EL34 tube burning extremely bright. So I switched it to stand by then turned it off. I turned the amp back on 5 minutes later and the tube wasn't doing it any longer.

Any major damage done?

It sounds the same. But just gotta make sure.

 

[Gibbyage]

bump

 

[Old BF Shred]

Could you describe this brightness?

Do you mean the filaments looked brighter than normal? or do you see a red glow on the plate of the tube?

The filaments all derive power from the same source; very unlikely one would be brighter than the others and then "fix itself" after power off/power on ("po/po").

However, the plates, if too much current is going through them, can do just this. If this "red plating" returns after po/po, then you likely have a defective tube and/or bias is out of range for the tube(s).
As the Stiletto has the infamous Mesa "non adjustable bias", a new tube would be in order.
Good luck!

 

[Gibbyage]

Well the tube it self was very bright. Unlike all the other tubes. Didn't notice the bottom of tube being red or anything. I'm gonna jam tonight with it.

If it was what you described is it okay to jam with?

The tube is burning like a normal tube now.

 

[Old BF Shred]

Hard to say for sure without me seeing what you saw.....
The plates are basically the visible internal "guts" of the tube.....right in the middle of the tube, not bottom.
I say this just to be sure we're on the same page.

I have heard that tubes can "run away" (not unlike transisitor's 'thermal runaway'), drawing excess current until the high voltage is removed (standby).
But this will cause the internals to "redplate" (more of an orange, actually) and there is no mistaking it...this will not look like the filaments glowing.
I'd keep an eye on it.....look after each song to see how it's doing. If symptoms do not return after a few hours of playing, you're probably OK, but as I said, I wasn't there....
While too much current, esp. a dead short in a tube, can cause damage to the amp, almost always, the fuse blows before this can happen...just make sure the fuse is the correct rating for the amp! :shock: There are horror stories on this board about not following that rule. :roll:

Just pay a little closer attention to the amp for a while to be on the safe side...and play as you normally would!
Good luck!

 

[Gibbyage]

Yeah it was the whole upper part of the tube. Bright orange glow to it.

Hasn't came back yet. Hoping for the best. Already had a terrible time with my Dual Rect and going through tubes.

Thanks for the advice.

 

[Old BF Shred]

When my Ace had a bad power supply capacitor, it caused a problem called "motorboating". Without a long technical description, it basically means the current through the tube can pulse up and down rapidly. This means the average idle current could be higher than what the tube can take. It is also very intermittent. I did see some "redplate" symptoms during this time, but I also know I had at least one defective tube, making it hard to say exactly what caused what.

My concern is you "may" have a similar issue. I have wondered if Mesa had a bad batch of these capacitors that made it into other amps as well. This kind of problem is very rare, though. I bought my Ace in Sep '07, but I'm not sure of the actual build date, or the batch date of the cap's. But then again, a tube can develop issues without any help of the amp. Note that a bad cap can cause the amp to seem like it's loosing power or is more distorted, so unless these are symptoms, too, it was likely just the tube.

The real question is if that tube sustained significant damage and will need to be replaced soon.
Basically, time will tell. If you have a real problem, you should know within a week or two for sure, so as I said, just watch it for a while.

Damage to the amp is highly unlikely as long as the fuse is the right size.