Tube Amp Hiss: Do They Need to "Burn In"

[Junk Yard Dog]

I've had amps that have had more hiss when I first got them and then the hiss died down a bit. Has anyone noticed this before? Do new tubes that maybe were not 'burned in' have more hiss when you first install them?

Thanks!

 

[glpg80]

An amplifier that hums is certainly showing signs of capacitors which are faulty in the power supply, but white noise is indictive of how the ground plane is laid out by the designer and also tube related. I can't say I've ever had an amplifier that started out with a lot of white noise and then quieted down as it warmed up. Usually I have tubes that go microphonic or show signs of needing replaced when you hear that ocean effect in the white noise.

 

[scottosan]

I've had amps that have had more hiss when I first got them and then the hiss died down a bit. Has anyone noticed this before? Do new tubes that maybe were not 'burned in' have more hiss when you first install them?

Thanks!

In my audiophile days, I had an OTL headphone amp with 6SN7's and 6AS7's and of all of the NOS tubes bought most would his for several hours and there was a legit burn in and there were several hundred pages on the audiokarma forums specifically on burn in. That being said, I haven't quiet noticed this as much with guitars amps.