Blueish tubes in an Orange

[perogato02]

After years of playing on ss amps, I made the jump to a full tube beauty. My choosen poison is an Orange AD200b.
And yes, I am happy with it! I love the sound, the way it breaks up, overdrives ... it makes me go all gooeyyyy

BUT: my guitard pointed out that my power tubes had (and still have) a blueish glow.
Is this normal? Do I need to be worried about retubing already?

[hachi kid]

I'm not sure if it means that a retubing is in order, but I used my VK100 the last two days for practice (about 5 hours, a piece), and the center of the tubes were red hot while the outside was glowing blue. it sounded great, too. the guitar players said that was good. they did note, however, if it starts glowing purple, you've got problems.

[coreyfyfe]

Blue glow is perfectly fine. Welcome to tube world.

"Blue Glow in tubes
The blue glow in power tubes is a flourescence from the few ionized molecules of gas that still exist in the non-perfect vacuum achievable in tubes, driven to fluorescence by the high voltages in the tubes. Unless it is excessive, it is not harmful. Tubes with softer vacuums glow more. "

http://www.geofex.com/tubeampfaq/taffram.htm

[perogato02]

Cheerz, mates!
You made me happy (and much more relaxed) man

[Deathblade Eric]

It can be a sign of a bias issue too. I had an old '69 Marshall that'd glow blue after I re-valved it with 6L6's. Adjusting the bias slider brought it down but never completely got rid of it.

I liked it - sort of "visible electricity".

Pete.

[coreyfyfe]

Originally Posted by hachi kid

they did note, however, if it starts glowing purple, you've got problems.

Missed this the first time around. Glowing blue/purple (see pic below) around the base of the tube structure can indicate an air leak and thus a bad tube:

[BassmanPaul]

The blue glow in a power tube is caused by the tube passing current. All output tubes have this and it is quite normal. The bigger the tube the more noticeable it will be. Your photo Corey, is a beautiful picture of a happy 6L6GC. 6550s and KT88 show particularly well but if you look through the plate slots of an EL34 you'll see it too.

Paul

[coreyfyfe]

Originally Posted by BassmanPaul

The blue glow in a power tube is caused by the tube passing current. All output tubes have this and it is quite normal. The bigger the tube the more noticeable it will be. Your photo Corey, is a beautiful picture of a happy 6L6GC. 6550s and KT88 show particularly well but if you look through the plate slots of an EL34 you'll see it too.

Paul

That pic was given as a reference for a leaky 6L6 (link below), which is why I posted it. I haven't seen one glow around the plates like that, only around the glass, but I don't have the years of experience that you do, so I'll take your word for it.


http://thetubestore.com/blueglow.html

[billfitzmaurice]

Originally Posted by perogato02

my power tubes had (and still have) a blueish glow.

It's plasma. Do a Level Three diagnostic.

[perogato02]

Originally Posted by billfitzmaurice

It's plasma. Do a Level Three diagnostic.

I like the thought of plasma powered sound!