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How does sound change when tubes start to fail?

Maybe a silly question, but I'm wondering how I can tell when the output tubes in my Fisher 400 reciever start to die? When I had it refurbished the techs told me the 7868 tubes were nearing the end of their usable life. I feel like the top end is less detailed and dynamic than it had been in the past , HOWEVER, I just moved and have a new listening room with less than optimal speaker placement. Thanks
dakajoba
philjolet's avatar
philjolet
2,306 posts
 
I think you have bad tubes if you even have to ask... Any signs of disinterest in the music is usually one of the signs of tubes on their last legs as they tend to sound flat. I think you can typically expect about 2 - 3 years from a set of tubes in normal listening conditions...
larryi
4,038 posts
 
If your system sounds a bit tired and lackluster, it's either you or the tubes have started to go bad. Sometimes older tubes develop noise problems as well (sputtering and whistles, etc.).
mezmo
516 posts
 
Think of it this way, one of these days you'll have to retube the thing. Might as well get a set of new tubes now and try them out. If you hear a difference, well, then it was time. If you hear no difference at all, then put the old ones back in and rest assured that your time will come.
larryi
4,038 posts
 
Mezmo,

Very good advice. However, I am always trying different tubes so its hard to say whether the difference is attributable to wear or to the inherent difference between the tubes.
dakajoba OP
12 posts
 
Thanks so much for your responses. I hope my system sounding a little lackluster is not me! I hope its the tubes or new listening environment. Mezmo, your advice makes sense to me. Does anyone happen to have any experience with the new EH 7868 which I just saw advertised on the TubeDepot web site? Would I be 'better off' with used or NOS or try the new EH? Thanks again.
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