Tubes

[ez_willis]

When I had the Classic 30 turned around to take a picture of those tube retainers, I noticed there was a 'pinging' sound coming from the tubes. It's constant. I did a search and found a recomendation to lightly tap each tube with a pencil, so I did. One of the tubes sounded waaaay different than the others, so I pulled it out.

There's a sticker on the tube that says Ruby EL84R, DSS Matched.

The tube itself has a stamp on it that says Sovtek EL84/6BQ5.

There are 4 similarly sized tubes. 2 that are identical to the one described above, and 2 like this one.

My questions are:

1. Will it hurt to power up the amp to see if the pinging is gone?

2. Is it correct to assume that it's 'matched' to the other similar tube?

3. Do I need to(or should I) replace both of the Rubys with 2 of the JJ EL84's? Or can I just replace the one, if it is indeed bad?

 

[ez_willis]

Hang on.

I was getting ready to re-install the tube and I tapped lightly on the back of the speaker. I heard a rattle so I started poking around. I pulled each tube out until the offending rattle stopped.The first tube retaining clip might be the culprit.

Rattle, ping, I don't know.


I'd still like some answers to my questions, so chop-chop!

 

[ocnor]

All 4 of the power tubes should be matched. Get a matched quad of JJ EL84s.
https://ssl.eurotubes.com/cart/index.php?page=view_products&category_id=3&sub_category_id=18
Also be careful about tapping too hard on the tubes when they are hot or you could F**K them up.

 

[timthetortoise]

You really shouldn't hear sound from any of them when you tap. Any sound from impact is a sign of microphonics. The EL84 is a power tube so to pull one, you'd have to pull a pair. I'd play it safe and just order a matched quad of E84Ls. They last a little bit longer and have some sweeeeeeeettttt low end.

 

[Outlaws]

Hang on.

I was getting ready to re-install the tube and I tapped lightly on the back of the speaker. I heard a rattle so I started poking around. I pulled each tube out until the offending rattle stopped.The first tube retaining clip might be the culprit.

Rattle, ping, I don't know.


I'd still like some answers to my questions, so chop-chop!

Pull all the tubes and shake them next to your ear. My money is that some will make a lot of noise. Filaments rattling around is the problem. I shake all tubes before I buy them now (or before using if i order online) because quality control today is crap and I have gotten brand new tubes that are already bad.