rectifier tube noise - is this normal?

[aKnyght]

there is a distinctly audible "hissing" type noise coming from the 5u4-gb rectifier tube on my new power amp. to be clear, the noise is coming from the tube itself, not the speakers. i thought this might go away after a few hours of break-in but after ~60 hours it is still there.

is this normal?

cannot imagine that it is; however, given this is my first experience with tube rectification i wanted to check with others here.

fwiw: at this point i am just using the stock electro-harmonix 5u4-gb rectifier ...a $15 new production tube.

thanks!!

 

[mep]

I have never heard a tube rectifier hiss.

 

[MPW]

Could be a nearby cap that is failing.

 

[aKnyght]

thanks for the replies! i went ahead and ordered a new rectifier tube so as to definitively rule that out before escalating.

 

[ArnoP]

Additionally check if the tube socket contacts are still clamping enough since a tiny gap or partial contact could cause some arcing/sparking that hiss. Retention is possible depending on the socket....but....make sure all the voltages are gone!

 

[stereogeek]

You can verify if it is the tube hissing and not a nearby cap by using a small, long skinny screw driver. This sounds stupid but it works. Hold the handle end tightly to your ear canal and press the tip against the tube, instant redneck stethoscope. Also, after shipping, sometimes tubes have to be reinstalled to make proper contact as ArnoP indicated.