Sounds like a router or wi-fi extender/repeater.
I too would go with the elimination process described above. It has to be something in the house (unless you live next to a broadcast transmitter or a ham radio enthusiast). Good luck.
First of all, I live in an apartment. The building is pretty spaceous so I only have direct neighbors above and below me. The livingroom has a dedicated circuit (I can turn everything off on the main switch and leave the livingroom on).
I have tried the wifi of course. I only have one led light and it was one of the first things I tried. Nevertheless, it could be another banality..
I’m not sure how strong the wifi signal of my neighbors is, it’s just if I take the preamp and move it closer to my wifi router, it doesn’t get any worse. If I open the wifi menu on my cellphone the signal looks pretty strong tho. Four of them with a full signal.
Rather than looking for the source I’d try to make the phono section more resistant to the interference. Sounds like it’s high frequency, right? The bass driver is moving as well sometimes, like it was trying to push 20Hz.
Do you think there’s a chance it’s coming from the electrical circuit? I called an electrician and he will bring a dedicated 12V battery that can power the preamp. But does it even count when the other components are powered from the wall?
And yes of course, I have tried all the sockets in the room, even sockets from another circuit.
So far it looks like a matter of position of the preamp.
I brought 6 meters xlr cables so I’ll move the whole linestage on the other side of the room, leading the cables under the carpet to the power amp.
Just to try it.
If it helps, I was actually thinking of leaving it that way even tho the cables between the preamp and power amp are gonna be 6 meters. (Paul from PS audio is using long xlr cables in their n1 listening room as well ;)
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?