Should Tubes Look Like This? (Warning - Noob Question)

[Connor1a]

Should tubes look like this after a 2 weeks’ use? Not sure you can tell from the pictures, but the tube looks like its been been frosted inside (it was previously clear). The tube is new manufactured (vs NOS or used). These were not inexpensive tubes. My apologies if this is one of those noob topics I should immediately recognize. I appreciate your patience… Thanks much.

 

[Keith_W]

Yes, that's normal. What you see is called a "getter". When the tube is manufactured, a reactive material is evaporated into the tube. When it is sealed and placed under vacuum, the getter reacts with any Oxygen that remains. It helps to maintain the vacuum in the tube and take care of small leaks. Getters should look nice and silvery, if they start turning white, it means your tube may have a leak and at some point it will fail.

 

[mhardy6647]

@Keith_W -- and FWIW -- I cannot tell if I am seeing the white, oxidized 'getter' (barium oxide) vs. the metallic "plated" coating.
If the former, the tubes would have lost sufficient vaccum as to no longer function.

@Connor1a -- is/are the heater(s) in the tube(s) still glowing when powered on? and/or can you tell if they're working? If so, probably all is well...
but looking at that photo they look sickly to me a priori. Perhaps a hairline crack in the envelope where one of the pins passes through has allowed air to get in. You might be able to see such a crack by inspection of the tube base.


From Reddit, a healthy getter is seen on the tube on the right. The tube on the left has - ahem - lost its vacuum (so to speak) and is muerto.

Now, what @Keith_W said above is true -- the getter is there for a reason, and can, and often will (especially in power tubes) disappear slowly but surely over time as the tube ages. In power tubes, it also sometimes persists but discolors... but the white, powdery residue is a sign of wholesale (so to speak) incursion of air and is diagnostic of... well... and erstwhile vacuum tube, at least from a functional standpoint.

 

[Keith_W]

@Keith_W -- and FWIW -- I cannot tell if I am seeing the white, oxidized 'getter' (barium oxide) vs. the metallic "plated" coating.
If the former, the tubes would have lost sufficient vaccum as to no longer function.

I can't tell from that photo either, which is why I avoided commenting on it

 

[mhardy6647]

a 'typical' Amperex ECC83 (12AX7 to us Amurricans ) would look something like this.

(random internet photo... I might have a couple of Bugle Boys here, but they wouldn't be that pretty!)

Couldn't find a photo of a dead Amperex ECC83 (thankfully... that would be painful to view!), but here's an exteme case of a 12AX7 with air in it
The crack is not so hairline in this case!

 

[Connor1a]

My apologies for the poor quality photos. I’m not much of a photographer.

Staring at the tube(s), I actually have one of each.

One of the tubes matches the photo of the white “getter” where the tube is compromised. It has a milky white coating across the top of the tube. It looks like a spider’s web. When I power on the preamp, I don’t see the tube glowing.

The other has the silver “getter” which is desirable. When I power on the preamp, I do see the tube glowing.

Luckily, I’m within the return period (though just barely) for the tubes at Amazon so I can easily exchange them.

Thank you very much for the insight. You saved me loosing money on the tubes while I tried to figure this out. They weren’t cheap!

 

[DVDdoug]

When I power on the preamp, I don’t see the tube glowing. Does it get hot? ...Be careful!!! Is the preamp working?

Sometimes in a hybrid design (solid state and tubes) the tubes aren't doing anything important, or not doing much critical or important.

Why did you change them? Tubes do age and eventually wear out but they usually last several years. And in a good tube design swapping ("rolling") tubes won't make any difference as long as the tubes are in-spec. A bad design can be more sensitive to normal tube variations.

 

[Connor1a]

Why did you change them? Tubes do age and eventually wear out but they usually last several years. And in a good tube design swapping ("rolling") tubes won't make any difference as long as the tubes are in-spec. A bad design can be more sensitive to normal tube variations.

I feel like I’m a naughty child being called on the carpet in front of the principal….

Yes… …. …. I … … … rolled the tubes. There, its out in the open. I should feel like I’ve had a catharthsis, but I just feel the red heat of shame…. Seriously though, I bought an Aiyama T20 for my headphone chain with the specific intent of using it to try different tube combinations to test “tubiness” for myself. I understand the calculus. Tubes should be transparent unless they’ve been specifically designed to “not be”. Such is supposed to be the case with the T20.

I’m prepared for the flames from the audience….

 

[FrantzM]

I feel like I’m a naughty child being called on the carpet in front of the principal….

Yes… …. …. I … … … rolled the tubes. There, its out in the open. I should feel like I’ve had a catharthsis, but I just feel the red heat of shame…. Seriously though, I bought an Aiyama T20 for my headphone chain with the specific intent of using it to try different tube combinations to test “tubiness” for myself. I understand the calculus. Tubes should be transparent unless they’ve been specifically designed to “not be”. Such is supposed to be the case with the T20.

I’m prepared for the flames from the audience….

Emphasis is mine...

We don't need to , your own tubes are taking care of that

Welcome to the Forum. Stay. learn...As for tubes ... to paraphrase The Mandalorian: This is NOT the Way
but you already knew

 

[Roland68]

Should tubes look like this after a 2 weeks’ use? Not sure you can tell from the pictures, but the tube looks like its been been frosted inside (it was previously clear). The tube is new manufactured (vs NOS or used). These were not inexpensive tubes. My apologies if this is one of those noob topics I should immediately recognize. I appreciate your patience… Thanks much.

View attachment 487143View attachment 487144

This looks like air has been drawn in, or the tube wasn't properly primed, causing the getter to wear out unusually quickly.
The level of use suggests years, not just two weeks. The remaining residue also indicates poor workmanship and materials.
The tube would need to be destroyed to determine if the residue is from the getter or from heat damage to the glass.
The tube could also have become leaky due to overheating.

 

[Keith_W]

Why did you change them? Tubes do age and eventually wear out but they usually last several years. And in a good tube design swapping ("rolling") tubes won't make any difference as long as the tubes are in-spec.

There is the rub. My engineer friend who designs tube amplifiers told me there is no such thing as a matched pair of tubes. This is because tubes are expensive to manufacture, and unless they are wayyy out of tolerance, they don't junk them. They sell them, and most people can't tell the difference.

If the getter in the OP's tube is turning white, I would try to obtain a replacement from the manufacturer.

 

[Connor1a]

Looks like one of the pins was bent which may have cracked the base of the glass envelope. Probably started at the factory (assuming they tested the tube) and then I may have exasperated it when I inserted it into my preamp (though I was ridiculously careful). Regardless, it’s going back to the manufacturer…

 

[JSmith]

Almost as much as the amp;

Amazon.com: New Matched Pair Reissue Genalex Gold Lion 12AX7 / ECC83 / B759 GOLD PINS Tubes : Musical Instruments

Buy New Matched Pair Reissue Genalex Gold Lion 12AX7 / ECC83 / B759 GOLD PINS Tubes: Tubes - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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JSmith

 

[DanielT]

Looks like one of the pins was bent which may have cracked the base of the glass envelope. Probably started at the factory (assuming they tested the tube) and then I may have exasperated it when I inserted it into my preamp (though I was ridiculously careful). Regardless, it’s going back to the manufacturer…

View attachment 488066

Was the glass cracked, as it appears to be in the picture, when you received the tube? I think that you should have noticed that because it looks like a large crack. Plus, even a shard of glass has come loose.

Or do you suspect the crack occurred when you popped it into your pre amp?

 

[Eurasian]

Was the glass cracked, as it appears to be in the picture, when you received the tube? I think that you should have noticed that because it looks like a large crack. Plus, even a shard of glass has come loose.

Or do you suspect the crack occurred when you popped it into your pre amp?

I bet you that's what the seller will think!

 

[MAB]

Or do you suspect the crack occurred when you popped it into your pre amp?

This is likely what happened.

 

[Tom C]

I feel like I’m a naughty child being called on the carpet in front of the principal….

Yes… …. …. I … … … rolled the tubes. There, its out in the open. I should feel like I’ve had a catharthsis, but I just feel the red heat of shame…. Seriously though, I bought an Aiyama T20 for my headphone chain with the specific intent of using it to try different tube combinations to test “tubiness” for myself. I understand the calculus. Tubes should be transparent unless they’ve been specifically designed to “not be”. Such is supposed to be the case with the T20.

I’m prepared for the flames from the audience….

It’s not your fault you got a bum tube. It happens from time to time. It can be enjoyable trying out new experiences. It’s innocent fun, so what’s wrong with that? Sounds like you didn’t spend ridiculous gobs of money doing it, so where’s the harm? One downside of tube rolling, though, is that the pins and the socket get a little stress and wear each time you pull them out and replace, so there’s that aspect of it.

 

[DanielT]

This is likely what happened.

Then the question is, if you, like @Connor1a in #12, indicate that the pin was bent and that it in itself caused pressure on the glass when it was placed in the tube holder that caused the crack and the missing piece of glass. Which if that is the case, TS should be able to find the small piece of glass somewhere.
Please note this is just speculation on my part. ALSO, I am not a tube expert so if the pin that looks bent can have anything to do with it, I don't know. You or someone else who is knowledgeable about vacuum tubes will have to think about that.

 

[DanielT]

Sounds like you didn’t spend ridiculous gobs of money doing it, so where’s the harm?

Well...

They weren’t cheap!

Expensive or not. It's relative. If they are:

a 'typical' Amperex ECC83 (12AX7 to us Amurricans ) would look something like this.

Hardly completely free. Some randomly picked up for sale now:

Used 12ax7 amperex for Sale | HifiShark.com

Used 12Ax7 Amperex for sale on 400+ second hand hifi sites & shops. Use Hifi Shark to monitor pricing and global availability

www.hifishark.com

But okay, it's not about some ridiculous gobs of money. But on the other hand, around $400* is not exactly pennies. Isn't that a saying in the US: not exactly pennies?
*I don't know what TS paid. It was just an estimate of price based on what I saw via Hifishark

 

[Connor1a]

This is likely what happened.

I’m not so sure. I wouldn’t rule it out, but as I said, I was ridiculously careful placing the tube into the amp. Looking at the angle of the bent pin, that either happened in manufacturing or I hammered on the tube like a club-handed monkey when placing it in the amp. I mean, in order for the pin to have bent enough to break the glass, I’d have heard / felt the glass crack / shift. I’d then have needed to go back in and straighten the pin in order to get it to fit back in the socket. That just didn’t happen. If the pin was bent to an excess angle and then straightened, it happened in manufacturing not by my hands.

As for noticing the crack prior to installing, sadly, my near field eyesight isn’t what it once was. I also wasn’t primed to inspect the tube for those weaknesses. So no, I didn’t pick up a hairline fracture prior to using the tube.

End of the day, I’m reasonably confident that I didn’t start the crack on the tube... However, I definitely made it worse when I extracted it. Will the vendor be happy? No…, but then, neither am I. I have to go through the return process, look for replacements etc etc… It’s a PITA.

I do appreciate your comments… Thank you for those.