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. 
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Showing 3 responses by stereo5

I have had 2 bad experiences on eBay. Not for tubes, but for other audio equipment.  In one case, it was an Acrolink cable that never materialized after waiting 9 months.  The other was on an amp that arrived broken (not from shipping) and had a very hard time getting a refund.  Too many amateurs selling on eBay so now I avoid at all costs. 
I had problems with two NOS Mullard CV4003 tubes.  One went microphonic after a week and the other after six weeks.  I paid almost $100.00 each at the time.  Lucky for me Kevin Deal backs up his tubes and I got replacements that lasted a long time.  The ones I bought were Upscales highest grade.  I guess any 40+ year old tube can have problems.