Just to be sure - sometimes "stopper" will not have a signal pin (like the AudiioQuest stopper is just an RCA cover with no center pin), but for this test you want shorting plugs with the center pin. You want the signal shorted to the ground so there is no signal on the input (which is also why I said don't put them on the outputs - they will blow the amp on the outputs).
I no longer have the luxman, and not sure if my current preamp is susceptible -(solid state Sutherland PH3D). I will see if I can try something.
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@filipm if you are going to open up a wall socket to check things out, might as well check for DC voltage on your AC power too - just put your DMM to DC volts and the probes on hot and neutral - I don't think it would cause this issue as it typically causes mechanical transformer hum and vibration and not noise in the signal path. However, I suppose the tubes could be picking up that vibration if present via microphonics - and it is another thing that might not be present in another location.
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I believe I have heard something similar to this before - twice - but both were some time ago - the first time it was definitely a router. Turned off the router, problem went away. Someone near you may have a powerful router. That would explain why you do not hear it when you take the preamp elsewhere. Try putting the EAR next to your own router and see if the sound gets worse.
The second time, if I recall correctly, I believe it was a combination of my iPhone 6 and a Grado Sonata 1 cartridge (an unshielded cart) going into a Croft Micro 25 (12AX7's) - but it was intermittent. I was trying to record and occasionally a similar noise would cut in intermittently. I put my phone in airplane mode and the problem went away. It may not manifest in another location with because your cell may be working on a different cell frequency elsewhere or your phones's GPS was turned off, or your bluetooth was not connected to anything..etc..; I do not seem to have the problem any longer with my latest iPhone.
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From all the tests you have done, and the results, I believe that your noise is RF interference entering through your inputs and being amplified by the Ear as though it were an audio signal. I suggest getting some shorting plugs (cheap on Amazon) to verify this - just get two of those and connect them at the inputs (not the outputs!). Then listen to the amp. I suspect you will then have no noise at all (which is as it should be). If you have no noise, then that is how the sound is coming to the amp - not through the tubes, or the power, etc. The fact that you do not hear this noise when not in your apartment, and the fact that the noise reduces when you grab the cables makes me think this.
Some equipment used to come with shorting plugs way back when (my old Luxman R1050 had two phono inputs which came with these as they (shock!) amplified noise from my wifi router when not in use.
If this experiment has no noise, then not sure what you can do - either get rid of the source generating the RF (hard to do if it is not in your apartment), or perhaps the Ear has an RF filter (ceramic capacitor or an RF choke) on the input and it has failed. I seem to recall my old NAD preamps had these soldered inside on the inputs for this very purpose. The Ear may not have this at all, but it would be good to pop the lid and check - your Ear may have some kind of input filter and they have failed or their solder joints have failed and they are longer connected to ground?
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@filipm
"Is there a way to short the inputs without the input shorting plugs? (I have ordered them but it’s gonna take a while)."
Just take a cheap RCA cable, cut off one end and twist the signal cable and the ground/shield wires together. Make two of them, one for left and one for right, then plug the other still good RCA jack ends into the INs left and right. Viola, shorting plugs.
Paul at PS audio has a pretty good talk about it here if you want to get more detail on shorting plugs; Shorting plugs
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Ah - that is very telling. Of what, I am not certain, but it may suggest that your input RCAs are not connected (broken solder joint) to ground in their shields, or there is some other failure internally. If the shorting plugs are correct, it should be silent if the only problem here is RF interference. Is the sound coming from both channels? Try connecting only one output at a time (left or right) to see if one side is better than the other.
To make sure you have the shorting plugs correct, check the connection by using your digital multi-meter and touching the DMM probes to the signal pin and the shield on the plugs - make sure you have a positive connection (most DMMs have a connection test feature that emits a sound or beep when there is a connection.).
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@filipm (Perhaps) an easy test; take your DMM and with the Ear turned off, verify connectivity between the input RCA jack shields and the ground lug (not the case necessarily) or the output RCA jack shields. On my phono stages they are all connected together.
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@filipm
Hmm - perhaps I am missing something but the statement:
"It still acts as a regular cable though, basically an antenna. " - I am not sure is correct once you connect signal to ground. I believe all the energy on the input should be draining to ground at that point.
I just ran this same test (turns out I also created shorting plugs this way once way back when) with an admittedly quiet solid state phono preamp, and with an wifi router right next to the cut wire ends. When the signal wire was not connected to ground wire, I was picking up all kinds of noise from the router through the phono stage - move the wire further away from the router, the noise got quieter.
When I twisted the wires together - absolute silence - nothing, with the wires resting on the router, not even the usual phono stage ocean noise at max volume on the amp.
I wonder if your ground connection on your input RCAs (internally) are not connected (in which case, the shorting plugs would definitely act like an antenna). I suspect the EAR connects all grounds to a single point from the PCB to the case. Is that connection still good?
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I think your shorting plugs are doing their job, and you have verified that your input shields are properly connected to ground and that the problem lies elsewhere.
Have you verified your power outlets (in the wall) have good ground? You can get a tester cheap at a hardware store. That is another difference between your place and where the EAR worked just fine.
FYI, I just found this link and this guy details a lot of the steps you have done so far, including the shorting plugs. Worth a read -
Trouble shooting phono amplifier and SUT noise
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@filipm I am not convinced you have a broken or poorly designed phono stage.
Recap of the evidence so far:
1. You have a predominant 50hz hum in the noise as was analyzed previously.
2. Both the EAR and the ARC LS16 exhibit this noise in your apartment
3. Both the EAR and the ARC have three prong power inlets
4. The EAR routs its ground through the third pin of the power inlet as confirmed by your connectivity test. Presumably the ARC does as well. My Herron tube based preamp, and my Bottlehead tube headphone amp do this as well.
5. The EAR does not exhibit the noise when used in another location (when plugged into a power outlet not in your apartment)
6. The shorting plugs did not reduce the noise
7. Grabbing/touching the cables affected the noise
8. The troubleshooting guide I linked, Bottlehead's trouble shooting guide, and @hagtech 's guide all suggest a 50/60 hz hum/noise is a lifted ground
This evidence suggests you have a lifted ground, possibly either in your power strip, or in your apartment outlets. Assuming the LS16 is not broken or poorly designed, and exhibits the noise too suggests that the EAR may not be broken. That would not make your EAR broken or poorly designed, just not being used as specified (with a good connection to ground).
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@lewm - an excellent point - I was assuming the OP was on 50Hz AC power, based on one of his previous statements in this thread, and the circular plugs in the powerstrip in one of the pics he posted.
@filipm - are you on 50Hz AC or 60Hz AC power? (should have asked this question earlier.)
I plotted the noise spectrum in Audacity, and the 50hz buzz/hum is constant throughout the entire recording at around -17db though it does have very short spikes to -13db intermittently (I think this is the intermittent bursts lewm is talking about). And then there is another spike of a range of frequencies every four seconds.
From the Bottlehead trouble shooting guide:
"Buzzy hum, like a bee - This usually means a lifted ground connection. "
if a lifted ground, then where it is lifted is the question, but a cold solder joint is certainly possible, though I would have thought if so it would have shown itself when the EAR was used at an alternate location.
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@filipm You could get an outlet tester from Amazon or a hardware store - one that would show open ground/earth would be important. Search Amazon for "outlet tester Prague" (or UK) - You can also use your DMM to test (google how to do it, lots of hits) - just be careful - and use just your right hand to place the probes - do not use both hands - if the outlet is not connected to ground, you don't want to become the ground. If you can, I would get an outlet tester. They are cheap and a great thing to have in this hobby. You likely want to test your power cords too for ground correctness.
I've been in and tested many homes and apartments. Not all were wired correctly, even the newer ones. Check all outlets.
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@filipm - my calculations might be incorrect, but the EAR amplifies a those low frequency signals (the mechanical transformer hum is a pretty low frequency I believe) something like 2500 times depending on how low the frequency. First an equalization of 20db for the bass region of RIAA, then another 48 dB for its phono amplification according to the EARs specs. I wonder if lightly touching the tubes with a pencil eraser (thus absorbing some of that mechanical energy) affects it.
This may be caused by the DC voltage on the AC power that I mentioned earlier - easy to check, and you can filter it with device that goes in serial with the power, like the Van Alstine Humdinger or I think iFi has one too. Good test to take it elsewhere to see if you still hear the mechanical hum. Supposedly toroidal transformers are more susceptible.
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@filipm - I understand you are probably super frustrated by now - yes, you could go solid state, but the fact that the tubed units work fine elsewhere suggests the problem is not with your gear.
I suggest that if testing the power for DC shows that it is present, getting a Humdinger from Audio by Van Alstine. You can return it if it does not help. Just realize that atmasphere, who I am reasonably sure knows a lot more than me about this (I am just a hobbyist), is correct - transformer hum should not show itself in the audio signal, though he does say "extremely rare". Perhaps your situation is one of the more rare ones. As for damage, not sure - I think I read somewhere that the power company will fix it if very bad "for safety reasons".
I would also do what atmasphere suggested right away with your DMM - It would be a good idea to check the REF150 grounds as well, and like he said check for impedance between the ground and the chassis to ensure you do not have a grounding issue in the units. I would have thought that would present itself in all locations, but maybe it's worse at your place.
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@filipm the EARs transformer is pretty noisy mechanically at your place; suggesting a power issue. The battery test was interesting and you would think would rule out dirty power, but that may have also just demonstrated the same power issue - have you tried the battery test elsewhere (like at the friends place where the EAR sounds fine)? I suspect the same results.
I listened to the noise again - the noise is a pulsing sound over what looks and sounds like a ground buzz. This may be a stretch, but perhaps your EAR's power supply is near end of life and when combined with the transformer issues at your place, is sagging and recovering rapidly, like a motorboat noise. It may not occur elsewhere because the wall power is just better enough there to allow the EAR's power supply to keep up. This would cause the tube circuit to generate the noise in the output regardless of input (search tube motorboating on youtube).
Are the filter capacitors in the EAR's power supply original? They are probably over 20 years old at this point if so. I'd take those out and test them or just replace 'em.
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@filipm R16 could have been sacrificed due to a bad tube - which can happen in any tube gear - if that was the case be happy that was the only thing that died.
But - dpop and audiophile1 are correct - this is more of a puzzle than searching for that best sound. The EAR has quite the reputation, but if you just want fantastic sound and not this hassle, you might want to consider an alternate route.
For me, it’s both as I love a good puzzle and great sound. I will add that is seems to be similar for a lot of the folks over at audiokarma dot org - they have quite a few posts on building EAR clones over there, and so far us audiogoner’s here have not been able to solve this. They helped me through a number of puzzles in the past.
Back to your problem. It’s possible you have a combination of a power issue in your place and the EAR is not dealing well with it, potentially due to near failing components. If power is the issue the power company must fix it. But if they cannot, I’ve no personal experience on what you need to do. I would research double-conversion power units - (AC to DC to AC) with a complete separation from the AC power; I believe there some out there are running their audio completely on these things, but I think it has to be complete - no component can be plugged into the wall or your risk a ground loop issue again - so big and expensive. Make sure you can return it if it does not work for you.
On the EAR, given that you had to replace some parts already, best to replace all those electrolytic capacitors as well. I think the EAR came out in the late 90’s, and if this is an original unit, those electrolytic’s in the power supply especially may be near end of life. They are cheap and easy to replace. Just make sure to find units with the same capacitance with same voltage rating or higher and similar dimensions. Nichicon, United Chemicon 105+C caps would be good for the power supply. I would also while you are there reflow all the solder joints on the boards. Takes less time than you think, and that way you are assured there are no bad joints.
When you replaced those film capacitors, did you use new ones of the same capacitance and voltage? The voltage could be higher, but I believe the capacitance value needs to be exact or near exact or it could negatively affect the circuit. For R16, - same - did you use the exact same resistance and wattage value? I think higher wattage would be ok though, especially if the old one burned out for an unknown reason.
One other thing - I noticed the step-up transformers in your EAR - does pressing the MC/MM switch have any effect on the noise with the shorting plugs on? If so that may be your ground issue there - reflow the solder!
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@filipm I didn't see that R16 was in the power supply before between the filter caps - should have looked more closely. Not sure what would cause that to fail, but I wouldn't be surprised if it was dirty power (in truth I don't know). In any event, I think that even more supports the thought that you should replace all the electrolytic capacitors in the power supply section and reflow all the solder there as who knows what else would have been affected before the resistor failed.
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@filipm ok - sounds like a plan. Good luck to you!
FYI - one last thing - that 33 ohm value you found between the phono shields and the chassis on the EAR does not sound right - all the phono stages I have have negligible values (0.1 ohms) like your REF150 between shields and chassis and ground. I looked up the schematic of the EAR and suspiciously R16 is a 33 ohm resistor, and more suspiciously R16 was recently replaced. I am not an expert, but in the schematic it doesn't look like it supposed to be attached to ground. I'd recheck that one.
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@filipm wow - now we are getting somewhere - I think @atmasphere is right on track and @dpop has some great suggestions too. Why it sounded good elsewhere is still a mystery...I would have thought if this is the issue you would always hear this noise. Did you use the MC switch at your friends place and just not notice the what would be then lowered noise?
Also, one thing to get out the way, an easy one - are the leads from the R16 replacement touching the chassis under the board (or any of the other leads under the circuit board)?
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@filipm thanks for posting those pics. Very interesting..yes, if you want to put it back together the way it was you may need a new 33 ohm resistor, but those are cheap enough. That one looks like a Vishay-Dale metal film, which are often found in audio because of how quiet they are.
I searched the web for images of the EAR 834p to see if I could find some that did not have the resistor, but of the ones that I found were a good enough pic to see the wiring in this spot of the EAR - all had the resistor there. So it seems intentional.
This one appears to have the same resistor as yours..(you may have to click the plus sign cursor once to increase its size)
This one does as well.
This one is a great pic, with what appears to be a "standard" (cheaper) metal film resistor between the ground post inlet and the IEC ground, and appears to be connected to the PCB ground plane directly (which would then match your EAR if I read things correctly).
Look at the first one again though at the RCA input jacks - there is some component they have bypassing signal to ground - a capacitor perhaps for noise filtering? Showing my inexperience here, I have not seen a capacitor that looks like that, perhaps one of the more expert folks on the thread can tell us what it is. Likely a custom mod (especially considering the Hovland MusiCap capacitors in there that I am reasonably sure are not stock given their cost).
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@filipm - I think lewm is referring to R16 in the CRC filter in the schematic, which you said had to be replaced (he circled it in one of the images).
The linked images I posted and dpop sent show the additional resistor you found connected to the IEC inlet. Given that it appears in the other EAR pics we have found out there, with the same yellow heat shrink suggests that EAR built them this way. Might be a good question to ask EAR.
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@lewm - I have followed and appreciated your investigation and effort to make sense of the evidence, and I agree this is strange. The EAR has rave reviews, and it just seems improbable that Tim de Paravicini with his reputation would make this kind of mistake. Perhaps in the repairs to this EAR the OP talked about something wasn't put back together correctly - or it is a manufacturing defect and they got it backwards in production and put the resistor in the wrong place.
My Creek Integrated is wired up like atmasphere and dover were saying is the correct way, and my other phono stages are either battery powered or do not have an IEC third prong (powered by wall wart) - so I have own nothing personally to verify with - but you mentioned the Manley Steelhead - which in its current iteration has three ground connectors, and they do make a distinction between circuit and chassis ground, with separate ground lugs, and allow the user to make their own choice about the grounding scheme; though I strongly suspect they would not leave the chassis floating in any of them. So I think there is definitely something to what you were talking about at least for some phono stages.
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