I've spent the last three days chasing a ground loop/hiss issue. I have unplugged and replugged every combination possible, have tried different type of grounds to phono stage, tried different phono stages, different lines into the amp, different turntables and still when I crank the volume with nothing playing, have this hiss. At lower volumes I don't hear it, but if I turn it up, it's there. I probably would never listen that loud, but still worry that at base levels the sound is compromised. I've had this system connected for a month and don't know if the hiss was always there, or if, when I had to rearrange and reconnect due to Christmas and the wife factor, something changed.
My system is a Line Magnetic LM216IA tube amp, a Heed phono stage, a Rega Planar 3 TT (which doesn't have a ground wire) which plays to Audio Physic bookshelves and a JL Audio e110 sub. One of my biggest concerns has been the lack of ground with the Planar 3.
My system is plugged into a Torus Power Conditioner, so I thing I have that base covered into a dedicated line. With all these electrical precautions am I expecting too much asking for a black speaker background?
Will be interested to hear similar ground loop stories or thoughts on whether there are other issues that I haven't considered.
First question do you have a ground loop which is a low level humming sound or do you have a hiss?
A hiss is found in components sometimes with noisy tubes or high gain, and more efficient loudspeakers.
If you have a ground hum you may want to try cheater plugs one at a time first on a power conditioner, then on the amp and preamp one at a time on each component.
Also check your interconnects sometimes the connector looks good but you have a fine crack on the wire and you are not getting a good ground.
First thing to do is to unplug all components just plug in the amp do you have any noise?
Then plug in each component one at a time till you find the culprit.
Sounds to me like you’re just hearing the natural inherent noise floor of your system. When you "crank it" to hear the hiss, you’re almost certainly ratcheting up the volume control beyond unity gain and, thus, the noise becomes more pronounced. Possibly, noisy tubes are contributing.
Yes, first of all is it a hum or a hiss? A low mmmmmm sound or a slightly higher shshshshshsh sound?
Try disconnecting (completely) first your turntable, then the phono stage. Does the amp+speakers still hum/hiss. Also disconnect the sub. One at a time. Try all the other things suggested too. It’s a slow process of elimination. Hopefully, you’ll find the problem. OR, one or more tubes may be noisy and as also suggested, it may be inherent to the system as it stands.
Hiss is the noise floor of the electronic components. U cannot get rid of it unless u have tone controls are you are ok with turning the treble down. And that will help only so much.
Thanks for all the comments and help. With your assistance and more experimentation, it is pretty clear that what I have is hiss and not a hum. I guess it is an amp related problem caused by tubes. Not sure where to go from here or whether it is something I have had and never noticed or if it can be rectified.
Line magnetic makes a god product. What is the condition of the tubes? NOS replacement tubes may be in your future.... try some of the cv 4004 version of the 12ax7 or any of the U.S. made 12ax7's. JJ makes a good kt88 and I enjoyed the new tungsols too.
My questions would be: how loud is the hiss? How far do you have to turn up the volume control before you start hearing it? Is it audible in the range that you use to listen to music? In my experience a phono stage will almost always generate significant hiss if you turn your system's volume control all the way up.
I read about people who can only hear a faint hiss if they put their ear up to the tweeter when the volume pot is wide open. I can’t even imagine how that happens. With every combo of gear I’ve had in my system (tubes, SS, pre/power, integrated, power conditioner, no power conditioner), turning the volume all the way up generates 60-85db of hiss (measured at the tweeter), easily audible from the next room. In most cases with gear I’ve tried, the hiss doesn’t become audible until the volume control is at about 50% (varies by component, of course), which is much louder than I would ever listen.
As long as the hiss is below the level at which you listen, I don’t think you have anything to worry about. You’ll drive yourself crazy (and spend a lot of money) trying to stamp out that last bit of hiss.
Does the tube configuration of your amp share a tube between channels, or are they separate/symmetrical? Can you try swopping some over from one side to the other?
How old are the tubes? Did they come with the amp?
I feel for you! I hope you get this figured out. I would not like or tolerate substantial levels of hiss. I had a problem with a ground hum before, but never audible hiss. Can you try someone else's amp?
You'll feel for me more after you hear this one. So, I'm trying to get my tube amp out of the rack to check out the tubes, disconnected the speakers (or so I thought) and dragged the amp to another rack when my audio physic bookshelves toppled and I got the second ding in a month. This one to the still pristine speaker which I've had for a month and a half. Aaaaagh! I'm beside myself for the second time in a month. $3000 speakers all banged up. Will deal with the ****ing tubes tomorrow. I do think the tubes may be the culprit. To answer some of the other posts, at low levels I don't hear the hiss, but I know it's there and don't know exactly when it creeps in. I'm trying to demo a Symposium isolation platform and my heart isn't into it if I don't have a good base level from which to compare. Aaaagh!
Udog, it sounds like it's a noise floor issue. Your DC likely isn't quiet enough so you are hearing some noise that it isn't filtering out. You have a few options, you can, if you know how to work on audio equipment without killing yourself, add smaller filter caps to bypass your current capacitors. .1 and .01uf may help. One common problem is the heater voltage, it's usually AC. If your amp is push-pull, than only the driver tubes on the input would need to be converted to DC, but AC uses less current as it's only putting out full voltage/current at the peaks of the sine waves, so while you can buy AC to DC converters on eBay, your transformer almost certainly can not sustain the higher current DC supplies, so you would have to buy another transformer just to run the DC which I believe uses 1.8 times the current AC uses, but just double it to be safe. I think 6SN7s use about 1.3 to 1.5 amps AC, so you would want a transformer that can supply about 3 amps per tube. Often that will cure your problem. Otherwise if it's really driving you crazy, a completely new power supply may be needed. Another option might be a new amp. Don Sachs makes an amp that puts out DC that is so quiet that the AC noise is in the micro volts, you can't hear that even with the most efficient speakers there are.
The small filter caps won't help. The heater voltage hypothesis is not relevant in this case. The user is hearing quiescent current flowing through the electronics. This is normal.
I was way off on the 6SN7 heater current, it's 600ma AC, so if you have 2 you would want a 2.4 amp DC capability but I am a big believer in potential, so I would want 3 amps DC available.
What’s the s/n ratings on your components. If they are not close that could cause your issue. Also have you biased the amp? If not you might want to start there
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