Quote:
Originally Posted by JimmyM  There are a lot of tube amp myths that get spread by people who never touched tube amps. This would be one of them. There is nothing about tube amps that's any noisier than any other kind of amp. My tube amps are extremely quiet. So are my SS amps. |
Well, yes and no. A well designed tube amp is very quiet, but remember that the noise floor in any signal chain is essentially set by the first preamp stage. All electronic parts, including resistors, produce noise called thermal (or shot) noise. This increases with temperature, and is why systems with
very low noise preamps (like radiotelescopes) are often cooled with liquid nitrogen or even liquid helium.
Tubes, because of how they work, have additional sources of noise unique to them, like flicker noise and partition noise. Triodes are quieter in preamps than pentodes or tetrodes because triodes do not have partition noise - it's a product of the geometry of the more complex tube types, specifically, having a screen grid.
The high gain triodes commonly used in preamps get noisier as they age, because of the additional source of flicker noise. I think that's where the old wives' tales are rooted.
Transistors also have this aging behavior for different physical reasons. If it gets too noisy, then it's bad, no matter whether tube or SS.
You'll hear some hiss from amps, even very good ones, if you boost the high end enough, and your speakers and ears will reproduce it.
Prolly (apologies to speling purists
) more than you wanted to know, but there ya go.
