It always seems that I find tube failure being preceded by increased noise, such as when a tube in my phono stage started kicking off big thumps through my speakers and subwoofer. It is often difficult to hear when tubes have aged because they slowly deteriorate over time, whereas when you change them you get all of the performance back at once. Often you will just get a dulled performance over time.
Listening for tube degradation
Hey, just wondering what specifically there is to listen for in regards to tube degradation. I don't have access to test equipment so I have to rely on my ear to determine if certain tubes are on their last legs. I've been able to notice a definite "scratching" or muddied sound whenever one or more of the tubes are in need of replacement. However, I find myself replacing ALL of the tubes since I can never pinpoint which exact tube or tubes needs replacing. Also, are there any visual cues to look for (ie.output tubes glowing brighter than others)? I have a 15W integrated tube amp that you can look at on my system page.