Dover, You wrote, directed at me, "There is 230 volts floating around - you should be more careful if you are going to give advice on this forum." Your advice directed at me is good advice for all of us. However, I don't see where I advised any action on the part of the OP; I was merely trying to make sense of the written and pictured information, and I wrote here what I thought was true based on that information only.
Filip, I just read a few reviews of your new phono stage. It is interesting to me that it claims to be balanced but offers only SE inputs (the claim is you can feed the RCA jacks in balanced mode or in SE mode), although it does have both SE and balanced outputs. Before consulting us usual suspects, why not ask your dealer or better yet the maker of the product? One question: Are you feeding the stage in balanced mode using SE cables?
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Indeed, if the 33 ohm resistor was in series between the IEC and the ground lug, on the one hand, and the PCB ground, leaving everything but the PCB containing the audio circuit at earth ground, that would be OK. But I still don't think we've hit upon the primary cause of the noise that the OP recorded and included in his initial post. (I realize Dover said all this before me.)
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Ok. My idea that floating the ground lug above ground along with the audio circuit is unconventional at best, based on what Atma wrote and my own measurements of two phono stages at my house. So I expect the ground lug on the EAR is in contact with the chassis. The ground lug is at chassis potential. Therefore I assume the IEC ground must not be directly connected to the chassis. (If it is, the 33 ohm resistor does nothing.) So, the 33 ohm resistor floats the whole device, chassis included, with respect to the IEC. That IS strange.
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So that 33 ohm resistor we see in the photo, which is in series between the threaded screw and the 3rd pin of the IEC, according to the OP, is either doing nothing or the chassis is floated by the 33 ohm resistor which I certainly agree is not the best idea. The OP has dropped out so we may never know. I am going to get my meter to see what’s up with the ground lug on my Steelhead. It looks to be isolated from the chassis.
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It’s possible that we are arguing because our two countries have different codes re grounding. Everything I have written is based on how things are done here in the US. The 3rd prong of the IEC is earth or AC ground. Correct? We see here that there is a 33 ohm resistance between the 3rd prong or earth ground and a screw that we agree is a ground lug. I take it to be the back side of a typical grounding scheme to be found on many phono stages which is to be used to ground the turntable or tonearm. There is no significant current or voltage on the ground wire coming from a turntable chassis or a tonearm, so there is no danger of blowing that 33 ohm resistor and making the chassis dangerously "hot". This is why EAR could get away with what appears to be a 1/4 Watt resistor or 1/2 Watt at most. By my way of thinking, that 33 ohm resistor is to float the AUDIO ground with respect to earth ground. We also see that the screw is directly connected to the PCB, and I assume it is soldered to the ground plane. This is not dangerous and is a ploy to reduce noise. For me to be correct, I would need to know that (1) the screw we see is NOT touching the chassis, and conversely (2) the 3rd prong on the IEC connector is directly connected to the chassis. (That would mitigate your legitimate fear that the chassis is floated.) So, the lug and the audio circuit are both floated by 33 ohms over the AC or earth ground and the chassis. That is OK in the US, where the AC receptacle is connected to a solid earth ground in every home that is up to code, by the 3rd wire.
I am not an EE, so I would welcome correction if I am off base. I don’t want to be giving advice that may lead to a dangerous situation.
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I see now that there is a difference between your thinking and mine. I perceive the ground lug, which is meant to be used to ground the turntable or tonearm or both to the phono stage, ought to be or can be floated along with the audio circuit with respect to earth ground. By my way of thinking, that actually makes the most sense if you are going to float the audio grounds; you want the upstream gear to be grounded at the same potential as that of the on board audio circuit. It seems that you want the ground lug to be at AC or earth ground, which is certainly not "wrong" either. In my way of thinking (float the ground lug), the photo shows exactly what you’d want; the ground lug for external upstream equipment is floated above earth or AC ground by the 33 ohm resistor shown in the photo and which we are told is attached to the 3rd prong on the IEC. Likewise, the ground lug is therefore at the same potential as the on board audio circuit by virtue of the other green/yellow wire which attaches the ground lug presumably to the ground plane on the PCB of the audio circuit. I see nothing wrong there. For all of the above to hold water, we also need to know that (1) the ground lug is not in electrical contact with the chassis, where it passes through the chassis wall, and (2) the 3rd prong of the IEC is directly in contact with the chassis, keeping the chassis at AC or earth ground. The OP can easily verify those two points by his ohmmeter; there is no need to de-solder anything, if the meter verifies that the IEC is in contact with the chassis and the ground lug is 33 ohms away from the chassis.
From what I have been able to read, this practice of floating the audio ground is "new", in the sense of the past 20-30 years and is not required but only makes for quieter audio. I checked two of the many phono stages I have lying around here or in use. My original Quicksilver has a ground lug that is not floated. It’s about 25-30 years old and sounds excellent when I use it. My Steelhead has two ground lugs, both appear to be isolated from the chassis.
I have a Beveridge system in my basement. Its direct drive amplifiers are about 40 years old, like the speakers. In the original design, everything in the audio circuit was grounded to the chassis, and the chassis was not at all grounded to the AC, because the amplifiers were originally supplied with a hard-wired 2-prong cord. I assume grounding was originally supposed to be handled at the Beveridge preamplifier, designed by Roger Modjeski for Harold Beveridge. This is a bit scary since the amplifiers develop 3200V in the output stage. When I got the speakers up and running, there was a low level buzz that I found very annoying. After some consultation and reading, I cured it by (1) installing a 3-prong IEC connector for AC and (2) connecting its 3rd prong to a pair of back to back high current SS diodes that in turn connect to the chassis. This "yin/yang" topology *(not my term but coined by others who thought of the idea) isolates the AC ground from the chassis and from the audio circuit in a safe way and seems to work to completely eliminate the buzz.
Finally, this EAR unit works fine in other locations. And Tim de Paravicini, the designer of the EAR products was no dummy. For those two reasons, I tend to think this whole brouhaha over the ground scheme is a red herring. The OP has some external source for RFI entering his apartment, IMO.
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Believe me, I got it. I have a lot of DIY experience, as Atma-sphere will attest.
I just am not sure that all the reported information, by verbal communication and by photo, is internally consistent. That’s what I wrote. I was not contradicting you, but your approach seems to be dependent upon the verbal description only. What I see in the photo is that IF the 3rd prong on the IEC is directly connected to the chassis, somewhere not visible in the photo, and if the ground lug shown in the photo is isolated from the chassis where it perforates the chassis wall, then there may be no problem at all with the ground scheme. You and I are not in disagreement. I am only questioning the information we’ve received.
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I think I am losing my mind here. The photo showing the two green/yellow wires both soldered to what is said to be a ground lug may not be consistent with your earlier verbal description of what you measured, namely a 33 ohm resistance between "ground and chassis". First, and most important, that ground lug you show in the photo I take to be part of a screw clamp lug on the outside of the chassis, which is meant for connecting the turntable and/or tonearm ground to the EAR. If that is so, then that lug MUST be isolated from the chassis, i.e., your meter should show an "OL" or very high resistance between that lug and chassis if you were to disconnect both of the green/yellow wires from it. In the current state, it should show a 33 ohm resistance between that (audio ground) lug and the third prong on the IEC where you plug a 3-conductor AC cord, because we see the 33 ohm resistor in series with that pathway. There should be very low or near zero resistance between the ground lug (that threaded screw) and audio ground because we see that one of the two yellow/green wires is soldered to the PCB directly, presumably to its ground plane. There needs to be another wire or contact connection between the third (ground prong) on the IEC and the chassis. If so, then this is is all good. Not the problem. Without de-soldering anything, just put one probe on the 3rd prong of the IEC, which is earth ground or AC ground, and the other anywhere on the chassis where there is bare metal. You ought to see continuity.
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No, the 33 ohm resistor in the filament supply filter should not be causing your problem. I was just wondering whether you had inadvertently measured resistance across it in your earlier report.
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If you examine the schematic that someone else posted above, you can see there is a 33 ohm resistor shown in the schematic as a series element in a CRC filter for the filament supplies. I don’t know how you could have been measuring the resistance across that resistor, given your description of where you placed your probes, but if your probe was touching something that you could not see that was on one side of that resistor and the other probe was on the other side of that resistor, then you could have measured it inadvertently. Maybe you should retest that resistance between the two probes that you’ve earlier reported and which atmosphere remarked upon. That’s the only 33 ohm resistance that I cansee in the schematic, but of course you might be measuring the parallel sum of two or more other resistances.
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That photo showing a 33 ohm resistor partially encased in yellow shrink wrap looks like very amateurish work. Could be the ill advised work of a previous owner. Also, is that resistor connected at its other end? If not, it’s not doing a blessed thing.
You never mentioned whether tightening the transformer laminations, etc, had a beneficial effect on noise emanating from the chassis (not the noise that we started out talking about which contaminates your audio signal).
At this point you’re receiving a lot of advice of questionable merit, apart from posts by Atma-sphere. If you don’t have or can’t access local expert help, I suggest you pay attention to Atma.
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If the transformer itself is humming, try tightening down on the screws that hold it to the chassis, and on the screws that hold the laminations together. Sometimes the case of the transformer can be a little bit loose and this can allow the laminations to vibrate and produce a hum. Transformers by their nature do not transmit DC, but DC can cause the transformer to be noisy. Make sure the transformer laminations are tight and that the transformer itself is firmly affixed to the chassis, and then report back whether that did any good as regards this latest problem. Of course I do not expect this to cure your problem with RFI.
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Assuming the OP lives in the US, I think it's a bit too simple to blame his issue purely on bad grounding, if you listen to the recorded noise up above. First of all, there is an intermittent burst of 50Hz noise. In the US, we use 60Hz AC, and it's pretty well regulated at that frequency. Typical noise due to grounding issues is at 60Hz or 120Hz. Moreover, it's not intermittent; it's constant. This noise seems due to RFI or EMI from some outside source, though it's true that the susceptibility to the Interference could be related to a poor ground circuit somewhere. There are already a myriad of reasonable ideas for the source and what to do about it in this thread. I hope something works. I am now wondering about bad diodes inside the EAR or the ARC. I am also wondering what did happen or will happen when all the tubes are replaced, though that will not rule out a cold solder joint inside one or the other device.
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Although I don’t recommend tube rolling in order to improve sound quality, in this case it might be worthwhile to change all the tubes in the unit. It could be that one or more tubes is defective, thereby enhancing susceptibility to the noise. Even if that did not help, there is also the possibility that there is a cold solder joint somewhere in the chassis, possibly in a connection to a tube socket. So I would try the inexpensive and simple things first like shorting the unused inputs, and shielding the unit, and shielding the cables, but if that does not work you might want to take it to a knowledgeable technician who can measure the voltages.
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This is not an inherent fault of the 834P. Shorting the unused inputs is a good idea.
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Aluminum foil is fine for identifying the source of radiation but if it works you’ll need a more practical long term solution, like possibly tube shields or other.
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When you squeeze them, you create a ground via your body. I have a table radio in my kitchen. It reacts to the lighting over our sink, which is on the same circuit, and also to a Canary detector plugged into the same outlet. If I hold the radio antenna in my hand, the RFI noise over the radio gets much quieter. The EAR is not balanced, is it? Looks like you have an ARC linestage sitting on the floor; is that unit internally balanced? I presume the 834P is inside the green thing.
Incidentally, maybe you wrote in haste, but I would not encase individual tubes in foil. Bad for cooling. That's the beauty of well designed high quality tube shields; they draw heat away from the tube and actually extend tube life, besides blocking interference. If you’re going to use foil, I would suggest just wrapping the whole chassis in foil; of course, you will eventually have to figure out how to allow for the whole device to stay cool, unless you install shields.
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There is no need to buy tube shields from eBay. There are several reputable vendors in the US who sell them, and will probably help you out with installation. One business is tubes and more. Another business is antique electronics in Arizona. Sure, you could wrap your entire unit in heavy duty foil. See if that helps. Probably you want to ground the foil in some way..
The foil must completely envelop the unit, top and bottom, sides and rear.
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Tube shields might help but only vs airborne RFI or EMI.
I doubt tube rolling is going to help.
SS devices are as susceptible to this problem as tube devices, possibly more so because of wider bandwidth.
Can your phono really be powered by a 12V battery? I’d be surprised.
Tube shields or Faraday cage plus ferrite beads on ICs and AC cord ought to have at least an audible benefit used together.
very late at night or very early morning, do you still have this noise? If not, then I’d suspect someone in your building is the culprit.
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I wouldn’t waste money on new tubes. However if the 834 does not already have tube shields I would look into purchasing some aftermarket cylindrical shields designed to block EMI and RFI. Place one over each tube. Well designed ones also improve cooling and dampen microphonics .
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Probably you're wrong on both counts, but we shall see, if the OP keeps us posted.
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Whoa! It is way premature to ditch the preamp, which is a well respected product from an established company. And this problem is not typical of the unit.
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Can be through the air, through the AC line, or through some component. Do any of your components have a switching power supply? Is this phono stage electrically isolated from the turntable motor? TT motors put shmutz back on the AC line, and it's wise to isolate the TT from everything else. Are you saying that the AC supply to your audio is isolated even from the other apartments in your building?
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One more thing: dimmers. Are there any dimmers on the same circuit with your phono stage? And by burglar alarm, I meant the modern type that work through a wifi connection.
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Have you tried different electrical outlets in your home? What else shares the circuit that serves your audio system? Any fluorescents or LED lights in the vicinity? Any burglar alarms?
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