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Am I living in a vacuum? Or has anyone noticed

Has anyone noticed the crap Svetelana is selling lately for 6550c output tubes. I purched two sets of 12 in the last 6 months, they've had a 25% failure rate within two months. My amp has been thouroughly inspected and tested.
The conclusion is that the tubes are crap. One tube lasted about twelve hours before the grid current began to cause that beautiful blue glow, followed by noise and a red hot tube, not to mention a red hot audiophile running across the living room to shut down the reactor. After pulling the suspect tube out of my amp, I noticed what looked to be like 'snow' inside of the glass. When are Svetlana going to address this current obvious lack of quality control? One tube even has minute bubbles in the glass and is 'out of round'. I'm sure this one is soon to go as well. I don't mean to rant on, but anyone out there using 6550 output tubes, or for that matter KT88 and EL34s are eventually going to require replacements, and will be at the mercy of one factory- Svetlana/Sovtec/Electro Harmonix- it's the same factory with different names on thier tubes.
Buying NOS GE6550s is not the solution, as the supply is limited and expensive. Playing with tubes like they are lightbulbs, 40$ a piece short lived lightbulbs, is not the solution either. Buying a Levinson/Krell/Rowland solid state amp will keep my tunes playing for now, and ironically seems far more economical than my current situation. However, this does seem ridiculous and should be unnecesary. Any suggestions? Anyone else noticing this trend? At what point do tube equipment manufactors light a fire under Svetlana's ass? Is anyone on the verge of ressurecting the GE tube facility, and is it even possible?
HELP!
skipweasel
elevick
2,439 posts
 
Shouldn't KT 90's be a little more durable than the 6550 & KT 88's? Maybe your amp runs a little hot?
rives
953 posts
 
Why does someone with the moniker "clueless" have all the insight?
jw94055
125 posts
 
Another tube source that seems to know what they are doing
is triode electronics. Their web page talks about the
svetlana, not svetlana, situation.
zargon's avatar
zargon
453 posts
 
I did have some problems with 6550Cs this year and described the situation in some detail in a thread that seems to have been deleted. Basically, I bought a new amp and had a tube go out in 9 minutes, got another new amp from the manufacturer and had 2 tubes go out simultaneously within 200 hours, and had another another go out while on the bench for warrantee work.

I wasn't sure if I was just extremely unlucky or if there might have been some problems with the production of these tubes. Of course, the amp manufacture suggested that there was something wrong in my setup, but I am convinced there is not. It is entirely possible that a bad run could get out without detection.
skipweasel OP
17 posts
 
Thanks for the feedback. The amp I'm using is a Defy 7 Mk 4. The bias has been set a few % on the conservative side, as it has plenty of power. So "running hot" is not the issue. I've also had an experienced tech. inspect, test, and inspect the amp some more before I put my problems with Svetlana, (not Svetlana?,) out in the open. I should also mention that I have access to test equipment with the ability to check for grid current and that the failures I'm experiencing are happening just hours after running test on said tubes. My previous tubes were also Svetlana 6550Cs, and they lasted 2 1/2 years. So there clearly is a difference between old and new production quality. I'm looking forward to following up on some of the advice offered, as well as inciting a response from the Svetlana importer. Also, do any of you have JJ KT-88s in your amps? Further opinions and observations appreciated.
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