|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
70.50.36.143
A while back (about a year ago) I purchased a quartet of new production 300B's for use in a pair of Manley Neo-Classic amps. A few months ago one of the tubes failed quite spectacularly upon being powered up. Since then, the remaining three have all slowly died. Upon death each corpse displays only traces of the getters that once were, and there is gunk of some sort at the bottom of the internals. I am no expert - my tubes usually work! - but does anybody have any idea about what the problem was here?
PS. My 1998 Westerns and 3 of the 4 stock EH tubes work just fine, after 15 (!) and 10 years, respectively.
Follow Ups:
as noted, as they leak the oxygen is taken up by the getter material and it flakes off or turn white. Would seem to me to be defective tubes if the circuit is at the correct parameters, which I assume since your other tubes work fine and even if not, the getter normally would not be something that would change very much.
iBasso DX100,DX50 DX90. Chord Hugo. HiFiman 901 balanced. RSA Intruder, The Lightning. Fostex TH900 balanced, Hifiman HE-6, 560, 500, JH13 Pro balanced. Lyr2, Audeze. All phones balanced mostly with Whiplash cables. Photo gallery: www.pbase.com/jamato8
nn
BTW;WE tubes were designed for longevity. When used as telephone repeater amps, they were on 24/7 for years. The tubes used in the transatlantic line laid down in WWII lasted for 22 years, after US military asked them to build an especially durable tube.
I would suspect a defect in the glass sealing, but hard to pinpoint
Slight gas leak. Getters did their job until they were used up, then the tube failed. Glad it didn't take out your output transformers.
got a photo?
Sorry for no photo, am technologically hapless. Not a pretty sight anyway. Although the first tube that failed did put on a lovely little internal fireworks display. The rest just faded away with their getters...
I'm no expert on 300Bs, but it could be some form of contamination resulting from the manufacturing process that is slowly released by the heat generated by use. Hypothetically as it is released the getter does its job and is slowly used up. When gone the tube gets gassy and fails.
"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: