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View Full Version : Tube Question--blue/purple huecoming from 6L6'S


TREV FLINT
05-29-2009, 03:41 PM
I read somewhere that when you see a blue-purple hue coming from your power tubes that it would be a good idea to change them. Is there any truth to this statement?

The reason I ask is because I have noticed that my 6L6's are looking blue/purple when ON but not when in STANDBY. This could be normal I don't know, but I have also noticed more "ice pick", "shrillness" coming from my amp and I can't seem to dial it out and still have clarity in the sound.

any suggestions?

-thanks

5992
05-29-2009, 03:45 PM
Check out this link:

http://www.netads.com/~meo/Guitar/Tubes/blue_glow.html



I read somewhere that when you see a blue-purple hue coming from your power tubes that it would be a good idea to change them. Is there any truth to this statement?

The reason I ask is because I have noticed that my 6L6's are looking blue/purple when ON but not when in STANDBY. This could be normal I don't know, but I have also noticed more "ice pick", "shrillness" coming from my amp and I can't seem to dial it out and still have clarity in the sound.

any suggestions?

-thanks

TREV FLINT
05-29-2009, 03:48 PM
Thanks for the link...very informative.

davemccarthy707
05-29-2009, 03:54 PM
Run!!! Its warp Plasma!!........ Nah its cool almost all new production tubes have it.

oldschoolguy
05-29-2009, 05:57 PM
I think it's cool. I didn't know about it either until I got a new amp and, sure enough, there it was.

stratman_el84
05-30-2009, 08:07 AM
The blue glow is simply some electrons hitting the glass. The higher the voltage & current flowing through the tube, the brighter the glow. This has always been the case with tubes, NOS or otherwise. It is perfectly normal and expected.

There will be somewhat more or less glow depending on the particular tube, the plate voltage, and how much current is flowing. You can see it getting brighter and dimmer as you adjust bias or play through them and the current & voltage changes.

The visual clues to problems inside the tube envelope are bright flashes while operating, which is arcing inside the tube, and the other is a milky-white color to the "getter", the silvery-black stuff inside the glass envelopes' surface. This indicates the tube is either "gassy" or has developed an air leak. Slightly-gassy tubes' getters will have a milky color around the edges of the getter, while totally-gassed tubes or ones that have lost vacuum to a serious extent will be totally milky-white.


Strat

TREV FLINT
05-30-2009, 09:22 AM
thanks for the info