Slight blue tube glow....

[Sebby123]

I have a mark ivB with stock mesa tubes... on the far left power tube it glows red with a slight blue spot...
Anyways ive changed the tube and it still does it.. is this bad? should i take it to a tech or is it something not to worry about?

 

[ketiov]

Blue normal, red - not so much. From what I've read here it's time to take the amp to a tech, since you tried another tube and it still happened.

 

[Octavarius]

Does it glow really red/orange? Stronger than the others? Or does it glow normal red, like the other tubes, only with the weak blue glow?

A red glow is normal, if you're referring to the heaters (the permanent weak orange-ish glow that's there from the moment the amp is turned on). A weak blue glow on top of that is also normal, and it's because of the cobalt impurities in the plates. This comes when you turn the amp off standby. If the tube was red plating (intense red hot glowing on the plates (the grey metal structure inside the glass) and often humming coming through the speaker, sometimes even visible lightning inside the glass and major noise coming out of the speaker in case of a severe short inside the tube), I think you'd know. And the fuse would most likely go out shortly after.

 

[Sebby123]

Its the normal orange glow with a blue spot in the middle...

 

[ketiov]

Its the normal orange glow with a blue spot in the middle...

Care to take a picture?

If it is glowing differently than the other tubes, it could still indicate a problem I think. They should all be glowing relatively the same.

 

[acorkos]

lots of tubes do that...it's normal

swap the far left tube with the far right and see what happens

 

[Sebby123]

Ill take a picture and pm you i swapped the tube twice and the spot was allways in the same spot...

 

[JPM90th]

Does it look like this. I took this pic a few months ago. It's sweet!

 

[Sebby123]

Not as strong its just a spot of blue on one tube a little smaller then a dime

 

[Dutchman]

Does it look like this. I took this pic a few months ago. It's sweet!

Beautiful

 

[Octavarius]

Not as strong its just a spot of blue on one tube a little smaller then a dime

Honestly, it sounds normal and probably isn't anything to worry about. If it doesn't affect the performance of the amp in any way, or show any symptoms of tube issues, there's really no reason to worry in my opinion.