Tube Rolling w/Crack

[mSummers]

A blue flash and popping would tend to suggest gas.  Is the silver getter still silver, or is it turning white?

All silver

[attmci]

I bought a Telefunken 6080WA on eBay and was told that it tested 110/110 on a B&K with no gas and no shorts.  When I plugged it into my Crack, the heaters glowed brightly and there was a blue flash with a popping sound.  Upon seeing that I shut the amp down.  Does that sound like a bad tube?

The bad news is that after re-installing the old tubes, I had no sound in the left channel and intermittent crackling in the right, so I trued an old crappy set of headphones and they seem to work fine, so it looks like I blew out a set of 600ohm Beyerdynamic drivers.

Plug your 600 ohm headphone to another source to see if it works.

NOS tubes may give you a "pop" but not flash. Try to clean the pins and give it another try (of cause use your crappy headphone)

[mSummers]

The 600ohm set only has one channel when plugged into other devices, so they're definitely shot. I'm not going to try that tube again and risk damage to the amp.

I guess it's time to get a tube tester.  Any recommendations? 

[Paul Birkeland]

I guess it's time to get a tube tester.  Any recommendations?

Plug new tubes into the amp without headphones connected.

[mSummers]

One more tube rolling question.  In a lot of 12au7's I bought on ebay is a GE JG-5814A.  Is that a drop in equivalent to the 12au7?

[attmci]

The 600ohm set only has one channel when plugged into other devices, so they're definitely shot. I'm not going to try that tube again and risk damage to the amp.

I guess it's time to get a tube tester.  Any recommendations?

Sad to learn a headphone could be killed by a bad tube.

I have a Jackson 648. http://tubesound.com/2008/01/09/rebuild-calibration-of-jackson-648a/

There are a lot of good tube testers on the market. Make sure they had been calibrated so you can get correct readings.

[attmci]

One more tube rolling question.  In a lot of 12au7's I bought on ebay is a GE JG-5814A.  Is that a drop in equivalent to the 12au7?

Yes. I am using a CBS JHY 5814A now.

[mSummers]

Yes. I am using a CBS JHY 5814A now.

Thanks for the confirmation!

[BotEleven]

Any suggestions for a good replacement tube and online vendor?

[jjvornov]

Here is an interesting tube for you collectors out there.   I have a few Gold Aero tubes in 6CG7 and 6DJ8 form and they all test with amazingly high emissions and perfectly matched sections. From what i was able to find out they cherry picked the best tubes they could find from a variety of manufacturers, then graded and branded them.  Granted they started life as lowly GE 5998A's but i could'nt resist picking one up to see how it performs..  http://www.ebay.co.uk/itm/172262170880

@Doc, would look mighty pretty in a limited edition walnut cased Crackatwoa

I bought one of these as my first tube option for my Crack with Speedball. Im finding it hard to compare because I get a lot more volume out of the Gold Aero branded tube. But its also a more dynamic, less mellow sound than the stock tube. A very clear difference in presentation, but cant say one is clearly better yet

[12AU7-6SN7]

Hi again,

I just got a Tung Sol 5998 output tube from eBay. The weird thing is that when the volume is all the way to minimum, a loud buzzing comes from the headphones. It works if I turn it up, but this seems rather concerning that something is wrong with the tube. Is this something that happens occasionally with old tubes? My pop is an old radio tech and he had never heard of one doing something like this. No other tubes do this. Should I return the tube?

I do have a 6sn7 in the input tube socket with an adapter, but it was fine with the Cetron 7236 I was using before the 5998.

Edit: It doesn't make the noise with a 12au7 in the 9pin socket. Is using a 6sn7 adapter and a 5998 output tube a mismatch for some reason?

Thanks for any advice

[serpent68]

Hi again,

I just got a Tung Sol 5998 output tube from eBay. The weird thing is that when the volume is all the way to minimum, a loud buzzing comes from the headphones. It works if I turn it up, but this seems rather concerning that something is wrong with the tube. Is this something that happens occasionally with old tubes? My pop is an old radio tech and he had never heard of one doing something like this. No other tubes do this. Should I return the tube?

I do have a 6sn7 in the input tube socket with an adapter, but it was fine with the Cetron 7236 I was using before the 5998.

Edit: It doesn't make the noise with a 12au7 in the 9pin socket. Is using a 6sn7 adapter and a 5998 output tube a mismatch for some reason?

Thanks for any advice

I have the exact same issue as you, but unfortunately never figured out the reason why.  It happens only at volume 0, and only when a 5998 is paired with a E80CC / 6SN7 / 12BH7.  I believe a few others have experienced this phenomenon too.

What I do is to avoid volume 0.  Everything works perfectly, and the sound improvement from switching to e80CC (from 12au7) is more than worth it.

[12AU7-6SN7]

I have the exact same issue as you, but unfortunately never figured out the reason why.  It happens only at volume 0, and only when a 5998 is paired with a E80CC / 6SN7 / 12BH7.  I believe a few others have experienced this phenomenon too.

What I do is to avoid volume 0.  Everything works perfectly, and the sound improvement from switching to e80CC (from 12au7) is more than worth it.

Thanks for the confirmation of the issue on other amps. It does sound good with the 6sn7, but I like the 12au7 too.

[mcandmar]

More Gold Aero goodness on ebay, this time some E80CC tubes http://www.ebay.co.uk/itm/272312847324

I received the Gold Aero 5998A yesterday and from the brief listen its a very clean and detailed sounding tube, and tested with perfectly matched sections.   Need to spend some more time with it to form an opinion, but so far it seems to do a lot right, and not a long wrong.

[attmci]

More Gold Aero goodness on ebay, this time some E80CC tubes http://www.ebay.co.uk/itm/272312847324

I received the Gold Aero 5998A yesterday and from the brief listen its a very clean and detailed sounding tube, and tested with perfectly matched sections.   Need to spend some more time with it to form an opinion, but so far it seems to do a lot right, and not a long wrong.

The guy got a neg. feedback, and changed his user name on ebay.

He also labeled  Russian 6H13C tube as Mullard "6as7g" :

Link: http://www.ebay.com/itm/6AS7G-Mullard-NOS-3-Tubes-421A-5998-7236-6080-Little-Bear-P8-Upgrade-Component-/172264901551?rmvSB=true&nma=true&si=F73E1xNo0JlESKzU5H4ZSD1dweA%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557