That is a nice photo too. I have a quad of EL34's that do/look like that also.
Haven't heard of that tube type either (not that surprising for me I guess -- check out my avatar 😉 ) but do they happen to sound as good as 807's too?
Haven't heard of that tube type either (not that surprising for me I guess -- check out my avatar 😉 ) but do they happen to sound as good as 807's too?
Stray electron hitting the glass enevelope causes a blue glow. No flouresents it's a sign of a gassy tube.
As tube's get older they diffuse gas through the envelope and around the seals.
Nick
As tube's get older they diffuse gas through the envelope and around the seals.
Nick
In Jimi's life, and in the life of half of the people present at the concert in the Orange Bowl (where the Hurricanes play) the words Purple Haze referred to one of the two types of LSD that were widely available at that show (Orange Sunshine was the other). How would I know this?
You have already seen my 211 with a serious case of purple haze. It was an extremely gassy tube, that would not pass audio.
The tubes seen here are new Electro Harmonix KT88's. They have blue spots on the glass that are quite bright. The spots vary in size and intensity according to the music.
You have already seen my 211 with a serious case of purple haze. It was an extremely gassy tube, that would not pass audio.
The tubes seen here are new Electro Harmonix KT88's. They have blue spots on the glass that are quite bright. The spots vary in size and intensity according to the music.
Attachments
nhuwar said:
No .....I've been using 807's for over 45 yrs and thev'e all behave sim from first electron onwards. One can check this by measuring g1 reverse leakage current. That should dispel the porous envelope to a myth. The recent Svetlana's have very thick glass compared to some early KT88's which had glass thin as a wafer crisp.
The idea that cobalt causes the glow is also speculation. My 807's use cobalt free glass and the blue glow persists quite strongly. On warm up the strong blue is within the electrode geometry then spreads around the whole tube- These JAN 1950's tubes were made at the height of nuclear prolification testing so the glass had to be free of known impurities.
I agree that leakage around the wire outs can muckup tubes but most are made quite sound and should last indefintely. Most of the failures are mechanical.
In the 1950's most of the UK imports of 807's were rebranded KenRads (US/CN).
Just to throw the towel in, I have several old 88's which don't have any blue fluoresence.......any explanations ??????? And electrically behave just as good as others.
richj
The reason all high power gird tube made with ceramic to metal seal is kovar was susceptible to corrosion causing corruption of the seals.
But in the beginig the ceramics were bad for other reasons they used beryllium oxide in the seal so if you accidently broken a tube it could have severe health consequences.
As for diffusion through the glass it can happen when the tube is stored for a lon g time and exposed to helium this can cause diffusion through the envelope.
But the catch is it has to be in exposed to helium!
But in the beginig the ceramics were bad for other reasons they used beryllium oxide in the seal so if you accidently broken a tube it could have severe health consequences.
As for diffusion through the glass it can happen when the tube is stored for a lon g time and exposed to helium this can cause diffusion through the envelope.
But the catch is it has to be in exposed to helium!
diegot said:
Sorry, this was my very lame attempt at a joke. I'm sure Jimi was referring to drug use, as Tubelab says, when he sang "Purple Haze", and not to the blue glow in his Marshalls.
OT: Ever notice how perfectly the words for the Green Acres theme work when singing Purple Haze?
- Status
- Not open for further replies.