I've generally had good luck buying tubes on eBay. If they've tested the tubes and have a lot of old feedback you can read, I don't think it is any more risky than buying from a tube dealer.
Ebay Tube Blues
This might be a lesson of woes or perhaps just buyers remorse.
I bought 2 EL34 (EI Big Bottle) replacements and a set of 4 12at7ws (Phillips) tubes for a VTL ST-85. I bought them from sellers who had a resonable seller history, but as far as I could see, they weren't commerical sellers. Also, these tubes are common so I wasn't worried about conterfeits. Both of the sellers stated they were "new" tubes.
I installed boths sets of tubes according to VTL's instructions of muting the preamp and letting the tubes warm up for 10 minutes before I bias the EL34s.
Thats when I ran into the following problems. The 12at7s had two problems. One was so microphonic I had to replace it immediately. It had a nasty hum with the muted preamp. The other side had an intermident snap-crackle-pop. After that happened a few times out came the new 12at7s and back in went my old 5 year old ones.
As for the EL34s, I haven't been able to bias either of the new ones up to the factory suggested 300mA specification. I can get close (approx. 240 in one and 255 in the other), but thast's with the pox turned all the way up. The old EL34s bias just right in those sockets.
My question is: Are these issues just part of a breaking in sequence for the tubes or is there something wrong here. I thought I would ask here before going back to the sellers with these problems.
Right now, I think I have some bad 12at7s and it's time to return them. I not sure about the EL34s. Do you think they'll allow more current through once they have run for a while?
Any thoughts would be welcome,
Rick
I bought 2 EL34 (EI Big Bottle) replacements and a set of 4 12at7ws (Phillips) tubes for a VTL ST-85. I bought them from sellers who had a resonable seller history, but as far as I could see, they weren't commerical sellers. Also, these tubes are common so I wasn't worried about conterfeits. Both of the sellers stated they were "new" tubes.
I installed boths sets of tubes according to VTL's instructions of muting the preamp and letting the tubes warm up for 10 minutes before I bias the EL34s.
Thats when I ran into the following problems. The 12at7s had two problems. One was so microphonic I had to replace it immediately. It had a nasty hum with the muted preamp. The other side had an intermident snap-crackle-pop. After that happened a few times out came the new 12at7s and back in went my old 5 year old ones.
As for the EL34s, I haven't been able to bias either of the new ones up to the factory suggested 300mA specification. I can get close (approx. 240 in one and 255 in the other), but thast's with the pox turned all the way up. The old EL34s bias just right in those sockets.
My question is: Are these issues just part of a breaking in sequence for the tubes or is there something wrong here. I thought I would ask here before going back to the sellers with these problems.
Right now, I think I have some bad 12at7s and it's time to return them. I not sure about the EL34s. Do you think they'll allow more current through once they have run for a while?
Any thoughts would be welcome,
Rick