2. amps-preamps
  3. 155281-435

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 1 response by millercarbon

millercarbon's avatar
millercarbon
12,531 posts
 
Just because the tube fits the socket, doesn't mean the amp runs the tube. 

Bias is set on the amp. Changing tubes doesn't change the bias. 50 to 90 is nothing in terms of harm, certainly nothing to cause such a show as this. 

Clearly you have other problems. The lack of relevant details and providing irrelevant info being a bit of a clue as to the biggest one.
More to discover