Tube Rolling w/Crack

[cddc]

I believe @Tom-s once mentioned on Head-Fi that some Eastern-European sellers are selling those Thomson 6080 duds as NOS tubes.

The ones from reputable sellers like Langrex should be good.

[Colonl_Charisma]

I recently bought a new power tube for my Crack, and it occasionally makes a whistling/high-pitched noise. The noise is clearly audible if I put my ear near the tube (no headphones on), and when I put my headphones on the noise is coming through both channels. Never had this occur before.

Should I let the tube burn in for awhile?

[mcandmar]

Sometimes tubes can be microphonic, if you tap on the glass or press on it does the noise stop?

[Colonl_Charisma]

Yep, tapping the tube seems to fix the issue. This really only happens right after I turn the amp on. After it has been burning for a few minutes it stops making the noise.

[kill_surf_city]

Yep, tapping the tube seems to fix the issue. This really only happens right after I turn the amp on. After it has been burning for a few minutes it stops making the noise.

i'm having the opposite issue. my noise isn't there initially. but after being on for a while it starts up until i tap it.

[mcandmar]

Its just one of those things, i have a few 5998's that do that too.  Adding those damping rings to the outside of the tube can be enough to stop it.  I think its cause by the subtle vibration of the power transformer, which in turn gets the grid wires singing at the right frequency.   I have used a number of microphonic tubes, but these are the only ones i have seen that just start to sing without provication.

[Doc B.]

Cleaning pins and sockets often stops that type of oscillation.

[Colonl_Charisma]

I appreciate the responses mcandmar and Doc. After the first couple days of letting the tube burn, I've had no issues with the 6AS7G tube.

[Markkr]

Now that I’m all settled in with my C2A, I’d like to try some different tubes.

Can anyone recommend a good 6080 and 12AU7 that would provide a noticeable difference from the stock tubes?

[Paul Joppa]

Since brands vary with the market prices, you might want to identify the ones you have first. Just sayin' ...

[Markkr]

I’m relatively new to tubes, still watching videos and reading blogs as I don't really have much of a foundation in understanding them. I only have the tubes included with the C2A kit.

My hope is a list of 6080’s and 12au7’s that would be considered worthy of trying to experience differences in tubes. (While I learn more about them)

[Colonl_Charisma]

Here is a link I have found very useful in my tube rolling experience. Jeb (who has posted in the BH forum in the past) did an extensive review of 6080, 12AU7, and 6AS7 tubes over at Super Best Audio Friends. As always, these are subjective reviews, and based off what his ears told him. This was a good starting point for me, and it helped me when buying some tubes that I wanted to try out.

https://www.superbestaudiofriends.org/index.php?threads/bottlehead-crack.120/page-3#post-13651

[Markkr]

Thank you so much! This is exactly what I was hoping for.

[Colonl_Charisma]

You're welcome!

[Deluk]

If you go back to the beginning of this thread there is a lot of info about what is good and what is not so good. Mostly though, better is in the ear of the listener and opinions vary on most tubes. Don't pay big money if you are just experimenting.