Michael Elliot of Counterpoint talked extensively about tubes in my owners manual and refered to them as fragile little devices. Here is part of what he had to say on the subject:
"A tubes insides are far more fragile than the insides of a light bulb. In a light bulb, all the mfg has to worry about is long life and good light output. It doesn't matter if the filament wire is leaning to one side or if the coating of the filament has some loose flackes, the bulb will work. But a tube has about 1,000 times the requirements to operate satisfactorily. Everybody knows that if you shake a light bulb briskly for about 10 minutes there is a good chance the filament might break, making the bulb useless. The same concept applies to a tube used for audio, but to a larger extent".
Further he explains that the shipping process of tubes due to vibration cannot guarantee a perfectly working noiseless tube upon receipt. So far I have been fortunate and have yet to receive tubes that are noisey or don't work at all but that could change!
"A tubes insides are far more fragile than the insides of a light bulb. In a light bulb, all the mfg has to worry about is long life and good light output. It doesn't matter if the filament wire is leaning to one side or if the coating of the filament has some loose flackes, the bulb will work. But a tube has about 1,000 times the requirements to operate satisfactorily. Everybody knows that if you shake a light bulb briskly for about 10 minutes there is a good chance the filament might break, making the bulb useless. The same concept applies to a tube used for audio, but to a larger extent".
Further he explains that the shipping process of tubes due to vibration cannot guarantee a perfectly working noiseless tube upon receipt. So far I have been fortunate and have yet to receive tubes that are noisey or don't work at all but that could change!