2. amps-preamps
  3. 1333080250

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

Showing 4 responses by shoff

shoff OP
133 posts
 
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?
shoff OP
133 posts
 
Thanks again to all who have responded. (Sonic Beauty, reostat is not the culprit!) Although I plan to give CJ a call to get their take on the noise, for now, I'm going on the assumption that the noise is of the "normal, naturally occurring" variety and not associtaed with any malfunctioning equipment (although I might do some tube rolling!). I will post again if I'm successful in reducing or eliminating it. It is comforting that so many of you took the time weigh in. Thanks again!
shoff OP
133 posts
 
I called CJ today. They said the issue was most likely caused by the noisy Electroharmonics 6922 (stock) tube. They recommended a Telefunken as a replacement. As long as I'm tube rolling, what else would make sense? I think I'll start another thread and ask the community.
shoff OP
133 posts
 
It has taken me some time but I finally got fed up with the noise issue and replaced the stock Electroharmonics 6922 with a NOS 1960 Amprex 7308 tube. PROBLEM SOLVED! Not only did the noise completely disappear, the whole soundstage opened up, a veil was lifted from the music and I'm hearing detail, nuances and note decay that I did not know even existed in the recordings (and this was right out of the box with no burn-in!). OMG, what a night and day difference!!! This was the best $150 I ever spent. I encourage all CJ ET3 owners to give this a try.
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