Did I read on here that if you have blue rings on your tubes that's bad and need replacing? I have 1 doing that (closest to inputs, all the way to the left) oh and it a 79 single channel 100 watt marshall combo amp. It still sounds good to me but what do I know I used ss for the first 10 years before becoming enlighten
ring around the tubes
- Thread starter jasgav
- Start date
CoolCat
Well-known member
here's a bit from a great article,
i just changed some tubes of mine for the first time. frkn pricey, but apparently on EL84 1500 to 2000 hours. So we'll see how long they go, the originals were form 2005 so thats about right probably on the hours.
Blue is Bad....in general. Cherry Orangey Orange white Orange is good..
C. Blue Glow -- what causes it?
Glass tubes have visible glow inside them. Most audio types use oxide-coated cathodes, which glow a cheery warm orange color.
And thoriated-filament tubes, such as the SV811 and SV572 triodes, show both a white-hot glow from their filaments and (in some amplifiers) a slight orange glow from their plates. All of these are normal effects.
Some newcomers to the tube-audio world have also noticed that some of their tubes emit a bluish-colored glow. There are TWO causes for this glow in audio power tubes; one of them is normal and harmless, the other occurs only in a bad audio tube.
* 1) Most Svetlana glass power tubes show FLUORESCENCE GLOW. This is a very deep blue color. It can appear wherever the electrons from the cathode can strike a solid object. It is caused by minor impurities, such as cobalt, in the object. THIS GLOW IS HARMLESS.
* 2) Occasionally a tube will develop a small leak. A tube showing this glow should be replaced right away, since the gas can cause the plate current to run away and (possibly) damage the amplifier.
http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm
i just changed some tubes of mine for the first time. frkn pricey, but apparently on EL84 1500 to 2000 hours. So we'll see how long they go, the originals were form 2005 so thats about right probably on the hours.
Blue is Bad....in general. Cherry Orangey Orange white Orange is good..
C. Blue Glow -- what causes it?
Glass tubes have visible glow inside them. Most audio types use oxide-coated cathodes, which glow a cheery warm orange color.
And thoriated-filament tubes, such as the SV811 and SV572 triodes, show both a white-hot glow from their filaments and (in some amplifiers) a slight orange glow from their plates. All of these are normal effects.
Some newcomers to the tube-audio world have also noticed that some of their tubes emit a bluish-colored glow. There are TWO causes for this glow in audio power tubes; one of them is normal and harmless, the other occurs only in a bad audio tube.
* 1) Most Svetlana glass power tubes show FLUORESCENCE GLOW. This is a very deep blue color. It can appear wherever the electrons from the cathode can strike a solid object. It is caused by minor impurities, such as cobalt, in the object. THIS GLOW IS HARMLESS.
* 2) Occasionally a tube will develop a small leak. A tube showing this glow should be replaced right away, since the gas can cause the plate current to run away and (possibly) damage the amplifier.
http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm
