Tube PHONO preamp interference - RFI, EMI, bad grounding?

@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.

@ejb14 

These had to be replaced. R16 died, the others were replaced along with it. 

It stopped working for a while as I was experimenting with it. 

I'm thinking of sending it to the factory, at least I will write them again with a suggestion.

@dpop I have also tried RCA only interconnects with two of these chains. For example Bryston B60 doesn't have XLR inputs. Now I'm only using XLR between a preamp and a power amp. 

33 ohms were measured on the EAR's phono ground pin or any screw (chassis) and the ground pin on the inlet. All the other solid state phono stages worked fine. Maybe except a Primare R15, there was a pretty loud surface noise, kind of like white noise. 

I always thought it was a subjective point of view, my girlfriend keeps telling me I only keep analyzing the system (of course when I'm not happy with the sound). Nevertheless I always had a feeling there's not enough juice in it, specially with the Bryston B60, it wasn't stable, sounded weak or lean sometimes. I was always surprised when I took the amp elsewhere. 

What else can we measure on the AC line when an electrician comes over? 

There's a simple voltmeter on the power conditioner I'm using for the sources. It shows some drops time to time, it's usually around 228-229V but it goes down to 225. If we find out the AC line is horribly dirty and unstable, is a power plant good idea? Something like PS Audio PP12 (I'm just a bit confused now, I have seen some measurement that suggest it's an overpriced piece of crap and I'm being told to stay away from power conditioning)

So to be 100% sure Filip, while in your apartment, using a SS phono stage (for example, the CP60), and the turntable connected *to the* CP60, the noise goes completely away? Is that correct?  

if so, I kind of agree with audphile1: At this point, the cure is worse than the disease. Dump this phono pre-amp and get one that’s properly designed to not be susceptible to this type of interference, at least within your setup (or simply use the CP60's TT preamp, if that is quiet). Seriously. You’re going to drive yourself nucking futs.

It's almost guaranteed that spending lots of money on parts (different RCA cables, ferrite cores, heavily shielded AC cables, new tubes, tube shields, etc.) is not going to fix this EAR issue. It's either a grounding problem (which I can't seem to diagnose via this thread), or it's an EAR design issue (the EAR can't filter and repel the high amount of interference in your apartment). You also mention that some components have already been replaced in the EAR. I'm wondering why they failed in the first place? That's not typical of (and very rare IMO), of audio gear, and in a way, sends up an immediate red flag for me.  

@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!

@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.