2. amps-preamps
  3. 135054-109337

Flash from power tube

Brand new to tubes here. Just recently bought a Jolida 302BRC here on audiogon. Previous owner put in Winged C Sed el34 tubes. Been working great since feb, but today when I turned it on, one of the tubes flashed and the amp wouldn't turn on. Stupidly I tried again, and same result. I removed the tube but don't really know what visible evidence there would be since i don't know what to look for lol. Anyway, my question is can I just order a replacement tube? Or when replacing tubes am I supposed to replace all 4? I know they were purchased at the tubestore.com so I could easily order 1. 
jp888
roberjerman
4,319 posts
 
It is always good to have spare tubes on hand for quick replacement. Current production tubes DO NOT have the longevity of past production (pre 1970's)  Meaning that they (power tubes) cannot safely handle higher plate voltages. 
roberjerman
4,319 posts
 
Buy old production USA, UK, Holland, German, Japanese tubes whenever possible for longevity AND sound quality! Avoid the rest!
ddzstereo
84 posts
 
For my last retube I used Winged C Sed 6550C tubes and had 1 of 16 fail after a couple of hundred hours at most.  Subsequently I have learned/been advised exactly what roberjerman has said "Current production tubes DO NOT have the longevity of past production"
jp888 OP
1 posts
 
Thanks for the help guys. Ordered a replacement tube and i'm going to open the bottom cover and see if anything looks fried
wolf_garcia
6,696 posts
 
There is no guaranty of longevity unless there is one from wherever you buy tubes, and that applies to NOS and new tubes. The only tube I've had explode in recent years was a NOS Phillips 12AT7 in a previous amp (a Jolida actually) and luckily I was in the room with it (jumped up and turned the amp off) and "thetubestore" warranty was still in effect. The amp was fine (whew). I've used new KT120s, KT150s, Sovteks (which are no longer made I think), JJs, Mullards, etc., and Gold Lion pre and power tubes and liked them, and I've heard very little regarding a lack of reliability with any of those and none of mine have blown (I had a quad of 120s last a surprisingly long time). I currently use new and old stuff, but the old ones are always NOS (Mullard, Amperex, Sylvania), and I'm often surprised at how durable tubes are in general in my guitar amps and pre and power amps. Not sure if any tube gets punished like a tube in a combo guitar amp, poor things.
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