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  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  (Threads | Answers | This Thread)

  Responses (1-28 of 28)
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03-30-12   Exactly how loud is the noise? is it only audible when you ...   Onhwy61

03-30-12   My first thought was a tube issue as well. tubes are freque ...   Mechans

03-30-12   Look into improving the grounding on your system.   Elescher

03-30-12: Mulveling
If the noise increases with the volume control, then that at least rules out the preamp's buffer output stage, and your amp.

In a review of the ET3-SE, it's mentioned that this unit uses a single 6922 tube for voltage gain. They didn't mention whether that tube comes before or after the volume control. If before - then it would be a prime suspect as the noise contributor. You could buy a guaranteed "low noise" 6922 tube from a trusted tube vendor, and see if that helps. If your source is an MC phono stage, then that could also be the (likely) cause of noise.

If all gear is in spec and the tube in question is not a noisy specimen, then it may just be that you've got an exceptionally high sensitivity amp & speakers - which would imply that you'd have to listen with the volume control quite low (i.e. you're throwing away gobs of gain - a prime candidate for a passive, though I still love the sound a good tube preamp even with some excess gain and noise floor).

BTW, being a vinyl and tube 'phile - I don't find a modest noise floor of the white noise variety (i.e. NOT ground loop hum) to be of detriment to the music.

Mulveling  (System | Threads | Answers | This Thread)

03-31-12   If you believe your system otherwise checks out and there ar ...   Ivan_nosnibor

03-31-12   All that said, a noisy tube could very well be the culprit t ...   Ivan_nosnibor

03-31-12   Thanks to all of you who have responded. here is some more ...   Shoff

04-01-12   Use low noise resistors in that circuit. but you are always ...   Hifigeek1

04-01-12   I take it the noise is apparently equally loud in both chann ...   Ivan_nosnibor

04-01-12   My experience with a cj et3-se was a soft white noise exactl ...   Rower30

04-02-12   Its normal to have a noise floor on any preamp. in this case ...   Atmasphere

04-02-12   Do you have lights on with dimmers on the circuit? dimming t ...   Sonicbeauty

04-02-12   Thanks for clarifying the volume-control/noise behavior. cle ...   Mulveling

04-03-12   Thanks again to all who have responded. (sonic beauty, reos ...   Shoff

04-03-12   I called cj today. they said the issue was most likely caus ...   Shoff

04-03-12   Amperex 7308   Hifigeek1

09-08-12   It has taken me some time but i finally got fed up with the ...   Shoff

09-09-12   That's what i   Hifigeek1

09-15-12   Good call, hifigeek1 ;-) vbr, sam   C1ferrari

12-02-12   I also have a et3se and have the same problem with the hiss. ...   Sdp6716

12-04-12   Good luck finding them. they are somewhat rare and expensive ...   Hifigeek1

12-04-12   For nos the amperex are my favorite 6922 followed by the sie ...   Onemug

12-04-12   Sdp6716, any tube can hiss or, worse, become microphonic, w ...   Tomcy6

12-10-12   Thank you all for the info. i spoke with cj directly and bo ...   Sdp6716

12-10-12   I have a dbx 3bx dynamic range processor that i have used in ...   Mapman

12-10-12   The 6922 is part of the 6dj8 family along with the 7308. the ...   Tomcy6

12-10-12   Whether you go vintage or current production buy from a repu ...   Tomcy6

12-10-12   The good dealers will be willing to answer your questions an ...   Tomcy6

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