Exactly how loud is the noise? Is it only audible when you place your ear next to to the tweeter dome or is it clearly heard at the listening position? Does it get progressively worse as you raise the volume control setting or stays the same? Have you ever heard the noise when music is playing?
It could be the normal sound floor of your electronics. It could be the sound of a noisy tube. It could be noise coming in over the power line. Answering the above questions will help narrow the possibilities. |
Look into improving the grounding on your system. |
My first thought was a tube issue as well. Tubes are frequently noisier than SS. In a pre-amp, any tube in the signal path and especially in a gain stage, should be very carefully selected for low noise. Even then, as tubes age, they can develop noise problems.
I find the tube sonic so appealing, that I am willing to sacrifice a very, very low noise floor. If it isn't audible with music playing you might want to live with it. |
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. |
If you believe your system otherwise checks out and there are no identifiable connection problems, grounding issues or faulty components and all that, then you are very likely indeed looking at electronic noise. This can be thought of as noise from the power lines coming into your house, but is actually EMI/RFI in general which also comes into your system through in-wall wiring, from within your components themselves and even through the air. There's also the issue of power supply crosstalk that's too lengthy for me to go into here, but it looks like some form of power conditioning solution should be on your system to-do list. Your assumption that that the noise may be preventing you from hearing all the music is correct, but likely much more than you may feel you have reason to suppose. There is the noise you can hear itself, which as you rightly point out can have a masking effect. But, there's also the purely electronic component to the noise which is far more destructive to the sound than most 'philes realize because it obscures the sound signal before it ever reaches the speakers...and that sound you never hear no matter how loud you turn it up or how good the system is. This second, purely electronic, effect of noise typically has a far greater adverse impact on the sound than the above acoustic one, but when the acoustic problem is present enough to be problematic you can bet the acompanying electronic component of the noise is disproportionately large and would well benefit from some power conditioning. PC has been around for a good couple decades or more so there is a ton of it out there these days, but traditionally there have been problems with getting it to properly filter out the noise without also restricting the audio bandwidth as well. Any more, all-in-one-box-solution power conditioners in the big leagues START at around 5 grand, but none of that is what you'd need to be looking at...IMO no one does, really. The one-box designs necessarily can't take into account the EM/RF problems with in-wall wiring and through the air, anyway...let alone they're unnecessarily expensive. For my money, I'd try going to Alan Maher Designs' facebook page and at least see how inexpensively things can be tried and/or get done. His new Quantum solution is what I'm talking about. Yes, I've tried it and no, I don't work for him nor am I acting on his behalf as anything other than a satisfied customer. Consider other options as you will, it's just that I don't see how you'd be able to impact the problem more effectively for less money (we're talking 40 bucks here, for something called the Q-mini, to dip your toe in the water, and even that may do it for you). You need to become a facebook friend of Alan's before you order, but he'll help you with that and all the rest. But, the main thing is that you'll not just be pleasantly surprised by the effects of good power conditioning, but absolutely blown the f away by the difference it makes...I mean, if not, then I think you may be doin' something wrong if you know what I mean, but I think you easily stand to come away from the original problem with the sound of a whole new system. Hope this helps. |
All that said, a noisy tube could very well be the culprit though if there's no noise at zero volume. |
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. |
Do you have lights on with dimmers on the circuit? Dimming the lights can make your system buzz..it did with mine. All the way on or all the way off with dimmer-equipped lights! |
Thanks for clarifying the volume-control/noise behavior. Clearly the unit is muting the output at volume=0.
I just looked up its specs: 25 dB of gain - holy COW that's a lot of gain (average these days seems to run ~ 11dB-14dB)! You're going to hear some noise floor with a linestage of such high gain, unless your amp/speakers are very insensitive (and thus would need all of that gain). Since it seems like the volume control comes before the tube gain stage, you're effectively "throwing away" gobs of gain without reducing the noise floor generated by it (I'm assuming you're keeping the volume control relatively low for listening). That's why your noise floor is discernible. I've got the same situation in my own setup (tube linestage, > 20 dB gain, 93dB/Watt speakers and 250-Watts@2V amps) - it's not detrimental to the sound quality in any meaningful way.
If this continues to bother you, you may consider sourcing some fixed attenuators to insert between your preamp & amp (i.e. attenuate AFTER the excessive gain stage). You'll effectively increase your signal/noise ratio by the amount of attenuation (maybe try 10dB). Just don't go too far to where you're gain starved on certain recordings.
Perhaps the gain is high so the 54dB phono stage can be used with a low-MC cartridge, with the extra linestage gain to cover the deficit. And I guess some manufacturers also try to accommodate for users with super-inefficient speakers. |
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! |
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. |
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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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Good call, Hifigeek1 ;-)
Vbr,
Sam |
I also have a et3se and have the same problem with the hiss. It is loud enough to hear clearly from the listening position. Where do you get NOS 1960 Amprex 7308 tube? |
Good luck finding them. They are somewhat rare and expensive. The majority of ones available now are pulls from old tube scopes, and old military test equipment. Remember, noise is a function of not only the s/n ratio of your equipment, but also the sensitivity of your speakers and gain as well. |
For NOS the Amperex are my favorite 6922 followed by the Siemens. Supply can only go down and price most likely will keep rising so I'd say get em while you can.
I've been using current production Genalex Gold Lion 6922 in my CJ ART and have been very happy with them. Even though they are Russian, they sound more like the Amperex. The EH (sometimes Sovtek) is what CJ ships with. They are okay but I prefer the above for my tastes.
The JJ's have a nice tone and they are cheap but I'd have one or two get weak on me in short time. I did like them though so I would just buy a few extras with each batch of 10.
But so far the Genalex's are the ones that are doing it for me it tone and longevity. I buy them from Jim McShane at www.mcshanedesign.net. |
Sdp6716,
Any tube can hiss or, worse, become microphonic, which sends a high pitched noise through your speakers.
I like vintage tubes myself and believe the expense and chance of getting a bum tube or tubes is worth it.
You can take your chances on Ebay. You will have good and bad experiences there. I see a lot of vintage tubes for sale on Audiogon, sometimes at good prices. Just hit the Tubes link under Accessories on the home page.
You can buy vintage tubes from tube dealers like Jim McShane, Upscale Audio, Tubemonger, Brent Jessee and more. Just google them. That is what I would recommend. You can discuss what kind of sound you are looking for and get recommendations from them and you can also request that the tubes be quiet. They don't need to be phono stage quiet though.
If you are happy with the sound of your current tubes minus the hiss, you can get new current production tubes that are quiet a lot cheaper. Talk to Jim McShane for those. |
Thank you all for the info. I spoke with CJ directly and bought a new EH6922.
At the same time I asked about tube rolling with a 7308. They advised against. They said ok to swap but stick with 6922. I thought the 7308 was the same tube. Is this not the case? I definitely don't want to risk damaging my new - in warranty pre-amp.
I also am wondering about how quickly the last tube developed the hiss. It's only 200 hrs old. I've read about the high gain in the ET3. Is it going to go through an expensive vintage tube that quickly?? |
I have a dbx 3BX dynamic range processor that I have used in the past that can help lower noise floor during quiet passages if needed.
I find its not needed with most good modern gear that is inherently very quiet when working right. Tube pre-amps are more of a challenge in this regard. Good quality tubes in a good pre-amp to start with is needed to keep noise levels low comparable to most SS gear I have found. |
The 6922 is part of the 6DJ8 family along with the 7308. The 6DJ8 is at the low end, the 6922 is in the middle and the 7308 is the big brother. These tubes vary in their electrical characteristics but that stuff is over my head.
Most people consider them interchangeable and opinions vary on which sounds best in a given preamp, as usual. I would stick with what c-j told you. They probably have a reason for it.
That's the problem with tubes. They can make noise, die prematurely, etc. That's why the engineers came up with transistors. Any tube can cause trouble at any point in its life, but if you buy good tubes it shouldn't be a common problem. It's the price you pay for that nice tube sound.
There are plenty of 6922s to try though. If you want to try vintage tubes, the Amperex, made in Holland or the USA, is a popular choice. If you want current production, check with Jim McShane. Tell him what kind of change you would like to make to the sound of your preamp and see if he can recommend something that would work for you. |
Whether you go vintage or current production buy from a reputable dealer. It will save you a lot of time and money. The good dealers are more expensive but their knowledge of tubes is worth the extra they charge. You have to learn quite a bit about tubes before you start buying them off Ebay or you'll end up wasting a lot of money.
There are good sellers here on Audiogon too. I can't vouch for anyone in particular, maybe someone else can. |
The good dealers will be willing to answer your questions and make recommendations. Don't be afraid to tell them you're not knowledgeable about tubes. If you're not sure after talking to someone, just tell them you need to think it over. They are used to talking to people who know nothing about tubes. It's in their interest to turn you into a tubeaholic and repeat customer. |
