I've been running my new PCB SSE for about three months now. I'm dismayed to report that I've had what appears to be a tube failure - but I'm suspecting it is due to poor quality tubes. Long before my original PCB got the burn spot, I purchased a pricey set of PSVANE KT-88-T II tubes. I went back and forth with the seller at length after a failure until they *finally* honored the warranty and shipped replacement tubes, as one lost vacuum after maybe 6 months. I hoped this would be a fluke.
Having this new set, I installed them in the SSE rather than risk a potential problem with the prior set of tubes (I was never certain WHY the board had a burn spot). I am disgusted to say that after maybe 3 months, I lost output (popping noises then silence) in one channel but there were not any other visible issue with the tube in question. Filament still lights and the getter is intact. After peeking inside the bottom of the amp and seeing nothing strange, switching the output tubes between channels immediately revealed the problem.
I got lucky in that I kept the original PSVANE tube from the original set that had not failed (premature loss of vacuum was the cause of the first failure). So I put that into the amp and it runs properly now. But seriously, a 50% failure rate in under a year is awful.
But this all leaves me wondering if I should return to the Russian tubes that have served for years without incident. I would hate for all the work on the new PCB to be damaged by questionable tubes. I was rather happy running a fully matched set of new production Tung-Sol 6550 / 12AT7 / 5AR4. My original EH KT-88 also provided a nice sound.
Saving that, are there any other manufacturers/nameplates I should investigate? Do others feel that NOS preamp tubes give a better tonal signature (Telefunken, Amperex Bugle Boy, Mullard, etc.)? Most of those aren't super expensive. Should the preamp tubes last indefinitely or will they develop signs of failure
I see there are now new production Telefunken. I'm curious if those live up to even a shred of their old namesake.
The one lingering question, with a few hours or more of use per day, is how long a set of tubes will last and if there is any way to detect tubes that are getting weak with or without a tester. I've always been uncertain unless there is an obvious sign (red plate or audio distortion), which would be best to avoid completely as far as I am concerned.
Any and all commentary is appreciated!
Having this new set, I installed them in the SSE rather than risk a potential problem with the prior set of tubes (I was never certain WHY the board had a burn spot). I am disgusted to say that after maybe 3 months, I lost output (popping noises then silence) in one channel but there were not any other visible issue with the tube in question. Filament still lights and the getter is intact. After peeking inside the bottom of the amp and seeing nothing strange, switching the output tubes between channels immediately revealed the problem.
I got lucky in that I kept the original PSVANE tube from the original set that had not failed (premature loss of vacuum was the cause of the first failure). So I put that into the amp and it runs properly now. But seriously, a 50% failure rate in under a year is awful.
But this all leaves me wondering if I should return to the Russian tubes that have served for years without incident. I would hate for all the work on the new PCB to be damaged by questionable tubes. I was rather happy running a fully matched set of new production Tung-Sol 6550 / 12AT7 / 5AR4. My original EH KT-88 also provided a nice sound.
Saving that, are there any other manufacturers/nameplates I should investigate? Do others feel that NOS preamp tubes give a better tonal signature (Telefunken, Amperex Bugle Boy, Mullard, etc.)? Most of those aren't super expensive. Should the preamp tubes last indefinitely or will they develop signs of failure
I see there are now new production Telefunken. I'm curious if those live up to even a shred of their old namesake.
The one lingering question, with a few hours or more of use per day, is how long a set of tubes will last and if there is any way to detect tubes that are getting weak with or without a tester. I've always been uncertain unless there is an obvious sign (red plate or audio distortion), which would be best to avoid completely as far as I am concerned.
Any and all commentary is appreciated!
I’ve got all Edcor transformers, the outputs are 5k/25watt. My favorite 12AT7 is the triple mica GE blackplate. For the power tubes I really prerfer EL34s, I have had a pair of the old =C= that I thought sounded nice, JJ, EH, NOS GE 6CA7, but I just got pair of the “reissue” TungSol EL34 and they are my favorite so far. They have nice clarity and great base. I also have a of EH KT88s that sound ok and a pair of Valve Art 6550s that will do in a pinch also.
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I've been using Telefunken kt 88's for about a year now and really like them. They're the best I've listened to in my SSE. Other residents have been JJ KT88, EH KT88, Chinese kt66, and Russian EL34.
My 12at7 is an original Mullard. I've tried a lot and that is the best by a long shot. I was surprised at how much of an impact rolling this tube had.
No rectifier tube.
My pre amp is currently populated with NOS Tungsram, which I love. They're much like Telefunken.
I've been using Telefunken kt 88's for about a year now and really like them. They're the best I've listened to in my SSE. Other residents have been JJ KT88, EH KT88, Chinese kt66, and Russian EL34.
My 12at7 is an original Mullard. I've tried a lot and that is the best by a long shot. I was surprised at how much of an impact rolling this tube had.
No rectifier tube.
My pre amp is currently populated with NOS Tungsram, which I love. They're much like Telefunken.
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