Any way to reduce pre-amp noise floor?


I have had my CJ ET3-SE tubed pre-amp for about a year now. When my system (McCormack DNA 500 amp, Esoteric X-05 CD, Aerial 10T speakers) is on and the CJ is set to "0" volume there is dead silence. However once I move the volume to to any level above zero ( no music playing, of course!) I hear a very soft but audible white noise. When I return the volume to zero the noise vanishes. This concerns me because I suspect that once the music begins to play, this noise floor becomes part of the overall sound.

This is my first "separates" system so I'm not sure if this is just a standard preamp phenomanon or if it is perhaps a sonic signature of CJ or if there is some real issue that needs to be fixed or can be tweaked. Any comments/suggestions will be greatly appreciated.
shoff
Thanks to all of you who have responded. Here is some more information to address your questions and comments. (1) I am running a Balanced Power Technology (BPT) CPC power conditioner with H-20 filtering. (2) All of my power cords have been upgraded from stock (Transparent and Cullen Cable). (3) CD is the only source component. (4) My listening position is 12 ft. from each speaker at which point the noise is only somewhat audible. (5) The noise floor DOES NOT increase as the volume is raised. (6) The 6922 stock tube used by CJ has less than 500 hours on it and I can honestly say that I CAN NOT hear the noise with music playing although I intuitively suspect that it is contributing to overall sound degredation.

Keep the comments coming but I think my first plan of attack is seek a low noise 6922 tube. Any suggestions?
Use low noise resistors in that circuit. But you are always going to get some kind of thermal noise from a tube depending on the gain of the circuit.
I take it the noise is apparently equally loud in both channels? Did you yourself ever buy a new tube (stock or any other kind) for the CJ before the tube you have now, and do you recall running into this issue then (or any other time with your system, for that matter)?? How old is the preamp and how long have you had it? As it is, at this point I'm leaning toward either possibly some sort of bias problem (some preamps have or can develope them) or the tube itself may even be out of spec, but I'm not real certain how to diagnose it short of being able to compare it to another identical tube and I'm not that familiar with CJ's, but I don't recall running across this being cited as a natural trait of CJ's before. I'd try calling a known reputable repair shop, it can't hurt to just ask some questions. If it were me I'd call Wayne, my go-to man at In-House Stereo Repair in New Jersey. I tust him because time and again he's both discouraged me from unnecessary repairs and been upfront about not charging me anything for repairs he found he couldn't see through to the end. They're on the web. But, if you could try another indentical tube briefly and it gave you the same results you're getting now, then I'd say the problem may be in the preamp's bias setting, and if the new tube stayed quiet, then the problem would most likely be in the tube you have now.
My experience with a CJ ET3-SE was a soft white noise exactly as you described. Tubes do have a higher noise floor than SS, but the noise (I call it SHOT noise or thermal noise) seem perfectly normal with tubes. In my situation, the shot noise seemed to be "fixed" so as the volume went up, it falls farther and farther into the background. Turn your volume knob "up" and the noise should seem to stay about the same, in other words. This is why it isn't too bad with music playing. Eventually, the tube went bad, and made a scratching or sizziling sound in one channel...time for a new tube.

Go here for some tube basics on noise. I think your unit is just fine.

http://www.john-a-harper.com/tubes201/#Noise
Its normal to have a noise floor on any preamp. In this case from the last post by Shoff the noise is apparently not affected by the volume control.

So it can be the noise of the line stage and that of the amplifier. A lot depends on how quiet the environment is; if very quiet then the noise floor could be heard.

I would not worry about it unless it gets louder over time. Then I would look at replacing the 6922 in question. Until then, I suspect a new 6922 will be as quiet as the one in there now.