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Vacuum tube ! And Warnings

To all out there who have Vacuum tube Amplifiers .
my friend just bought his first tube amp , it came with EL34 power tubes he wanted to get a bit more punch . He ordered on EBay  6550s I told him I would assist in fine tuning the bias.
he plugged them in we turned it on and a huge transient goes through one of the speakers and a surge through one tube . I shut it down waited 5 minutes then turn it on bias has a built in meter ,I checked they were over 90 +milliamperes maxed the meter. should be around 50. I removed them , he is sending back.the story here is many Ebay sellers don’t even test them they just get them from Russia and state as a match quad ,and runin for 24 hours . Never buy from anyone that doesnot  personally check them .
viva tubes, and upscale Audio are good , Jim mc Shane is good.
for vintage tubes, Brent Jesse recording, and Vintage tube services   I recommend. 
128x128audioman58

Showing 2 responses by oldhvymec

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oldhvymec
5,101 posts
 
I would never buy tubes off eBay. That was the first mistake.  

I've bought all kinds of Valves from eBay. A good visual, and a way to check is the only way a valve goes in my units, ANYWAY. I don't care who sold it... It has to get to you somehow, THAT alone is a reason to check it.. Normally, no problem, but there is that 20 foot slide across the the UPS, FEDX, USPS, trailer floor, into the brake lining being transported on the same trailer.. That's also had lawnmowers, condoms, and laddies brasseres (some men too) all on the same cargo run...SQUASH comes to mind....I've had a bad one or two, all signal valves though no power valves...just cheap, burn out before you could blink an eye stuff, with power valves.. 6L6 stuff usually.. Solvex is pretty good for the most part..
I like um...I just don't trust um....

Regards
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oldhvymec
5,101 posts
 
You know I though about what you did. That can't work their wired different, I don't think you can swap that valve. I'm not an EL34 guy.
Where's the bass?? But really, I don't think it's interchangeable.. Two different animals all together.. A guy told he could do it with VTL, from KT90, to EL34, with a flip of a switch, and of course a rebios (maybe he had some type of auto bios). My VTLs no switch, 6550, Kt88 or 90s no EL34 for sure..They are wired different...No plug and play....

Regards..
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