Tube question

[ZEEGLER]

What's going on here?

Matched Mesa tubes. One has the silver coating on the inside, the other doesn't.

Is this an issue?

[spawnofthesith]

I think no getter means that there is potentially a leak in the vacuum?

But I am not an authority on this

[Dave]

Are you saying the tube on the right doesn't have a silver flash on the top of the tube?

I think no getter means that there is potentially a leak in the vacuum?

But I am not an authority on this

If there's a vacuum leak in the tube the getter will turn white.

[ZEEGLER]

Yes the tube on the right is just clear at the top. It looks like there may be a very small amount of white residue there.

[GuitarBilly]

both tubes should have the silver flash but that could very well be just a small QC thing at the factory and it does not necessarily mean the tube is defective.

Aside from obvious things like frosted glass or red plating, it's hard to visually inspect tubes. I've seen pristine looking tubes test bad and vice-versa. If you don't have a tube tester, the best way to test them is really to put them in the amp and see if they sound good and hold bias. If yes, it is a good tube.

[greatmutah]

If it’s white the vacuum is gone. A little amount of left over getter that’s white lost it’s vacuum and most of the rest probably evaporated. Bad tube.

[duncan]

Yeah that tube is done.

Please see remnants of white residue:

[ZEEGLER]

Yeah that tube is done.

Please see remnants of white residue:

Bummer. That was one the extra tubes the guy gave me with the Roadster. It's interesting that the "getter" just disappears.

[Dave]

read up on what the getter is and it'll make way more sense

[EndTime]

The only oddity is they were grouped. I don’t think this matters. In fact I KNOw I have some old 6l6 without any getter. Either Chinese or TAD have some like this I’m sure. If they seal is busted that whole top would be white. I’d plug em in and see. If it’s a bad tube you’ll know.