Flash from power tube

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"

Thanks for the help guys. Ordered a replacement tube and i'm going to open the bottom cover and see if anything looks fried

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.

I had some issues with Winged C EL-34 in my primaluna.

This is ruining my desire to obtain a set of "winged C" tubes, although there might be some fun in waiting for them to explode…move the furniture away from the amp and get the extinguisher ready.