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View Full Version : How to detect tube arcing?


fredv
08-10-2006, 03:27 PM
I saw this terms many many times but couldn't figure out how to detect such happenning in the tubes. I need some education, please.
jdhdiggs
08-10-2006, 03:54 PM
Lick it. If your sizzles, you've done something wrong.

Disclaimer: This is a joke, not serious, do not try this...

BTW, I have no idea unless it looks like a lightening show.
fredv
08-10-2006, 04:20 PM
Maybe a new way to get high :D
mhardy6647
08-10-2006, 10:35 PM
Look for flashes in the tube. Listen for nasty cracks in the audio.
organ
08-12-2006, 02:16 AM
Yeah, what Mhardy said. Also, instead of flashes, sometimes you might see the tube get brighter and brighter until they go poof. I had a JJ 5AR4 arc in my ST-70 taking out the fuse.
fredv
08-12-2006, 02:35 AM
Yeah, what Mhardy said. Also, instead of flashes, sometimes you might see the tube get brighter and brighter until they go poof. I had a JJ 5AR4 arc in my ST-70 taking out the fuse.
Interesting, I have a JJ 7591 behaved like that. Before it died, it flashed and killed the Sovtek 5AR4 along the way in my Eico ST-70. I shall take a close at it in a tube tester!!
organ
08-15-2006, 01:39 AM
Keep an eye on it when you're testing. I'm staying away from JJ output tubes for now because they have some serious quality control issues. There are a lot of discussions regarding this on audioasylum.com
fredv
08-15-2006, 03:11 AM
Keep an eye on it when you're testing. I'm staying away from JJ output tubes for now because they have some serious quality control issues. There are a lot of discussions regarding this on audioasylum.com
That really sucks. Amongst all new production 7591, JJ sounds the best. In fact, I prefer JJ to the Westinghouse NOS 7591. I hope they will fix their ass. I kind of like their output tubes especially the E34L and KT77............
mhardy6647
08-15-2006, 09:50 AM
I don't think it's all of the JJ's. I have been using a quad of their EL84's for some time with no complaints, and I don't think I've seen anything on-line denigrating the EL84's in terms of QC. I think there were initial problems with the 7591's, which may be history now. I have a quad of these in a Scott LK-72 (brownface) but it has some preamp issues so I really cannot comment on them meself.
fredv
08-15-2006, 01:38 PM
The JJ 7591 went bad earlier this year. Since then, the remaining 3 and the replacement having been doing fine and providing nice tube melody in my bedroom. Quite frankly, I can't conclude it was the JJ's fault because the 5AR4 went bad at the same time, and this is the second bad Sovtek 5AR4 I experienced (died on a different ST-40). I just replaced my Svetlana EL34 (I believe they are very much like Sovtek from the New Sensor factory) with 2 new quad of E34L. There is absolutely no comparision to my ears!!! I hope the E34L will last ..........