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
I was just making a point nothing more
i have been using tubes for over 40 years 
and owned a Audio store I know how to bias tubes. My point was a lot of eBay sellers don’t even check the tubes they just 
go by what the mfg state I later checked
with a textronics tester 2 tubes were at over 100 most ma meters go to under 90.
that is why you buy tubes that should be within range under 70 ma for sure
6550-kt88 50-60ma is the norm
I tend to disagree as there are some long term excellent dealers on eBay. The trick is finding them, that’s all. I bought a whole bunch of tubes on eBay about 6-8 years ago , everything from Chrome Domes to Badboys to WWII Tung Sols, always had great results. 
stereo5
"I would never buy tubes off eBay. That was the first mistake."


In the last 12 months, I've purchased around $1k worth of NOS tubes from sellers on Ebay. Zero problems. Years ago, when I had an amp that used 6C33 tubes, I purchased at least $500 worth from sellers in Russia and the Ukraine. Zero problems. I always purchased from sellers that had 100% positive feedback.