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

Can I ask what you are using the Chord Qutest for? 
I had an issue like this caused by a streamer.

@filipm 

From your experiment, the cables might be more an issue than the EAR.

Try some Gotham Audio Double Reussen shielded interconnects - TT to phono and phono to ARC. - fairly cheap, but good quality and very good shielding, much better than many audiophile cables.

+1 on the Gotham interconnects. They are very good and can be bought directly from the manufacturer on line at a very reasonable price.

The best tube shield by far IMO is the IERC. They have ”fingers” inside that connect to the tube, reducing microphonics and leading away heat. 

@lewm That’s for sure - I’d only wrap the tubes or the unit into the foil for about a minute. It takes a while, about ten minutes before the tubes are warmed up. Sonically even longer, the real listening with the EAR starts after half an hour and then it’s just getting better.

Yes, that’s an ARC LS16 mk1. It’s balanced, I’m using Nordost Red dawn XLR cables. There are different cables on the picture, balanced as well, about 20 feet long - I was trying to move it on the other side of the room to see if the noise changes.

EAR 834p isn’t balanced.

I have tested the EAR with several components, Bryston B60 for example - same results.

@dover Thanks for the tip but is the issue is shielding, I’d rather just add shielding to any cable than testing different brands. That could get quite expensive. If it proves to be the shielding then I’d gladly buy one of these cables.

A simple shielding test could be again the aluminum foil. I have tried this before and it kind of worked but the noise didn’t disappear completely. The shield should be grounded, right? Maybe a piece of wire between the shield and the ARC preamp?

It would be the best to share the recording of the noise on some radiophonics forum. The sound is very specific so eventually I could find the source.. or am I being naive? I have tried googling things like "wifi noise" etc.

If there’s about 4 to 6 wifi networks, they may be overlaping.

A sound sample at 1:00"

@plumptonvinyl The Chord Qutest is connected to a streamer right now. I’m using a Allo Shanti linear power supply with it and it sounds very good. My streamer is a Raspberry Pi plugged into the router with an ethernet cable. I haven’t got the soundcard for it yet but I will upgrade it soon. It’s also powered from the Allo Shanti. I have had this problem before I bought the streamer

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?