Stillpoints ERS cloth for EMI/RFI

I can't say that I've gone as far as trying ERS cloth inside components. I got as far as trying it around cables and on top of various components in large, medium and small sizes of the material. I experimented with ERS cloth in two highly resolving system over the course of two days. The results were consistent - while the ERS cloth affected the sound, even in small amounts, the sound lost its sparkle and sounded rather compressed and wooly. I found out that even having a sheet of ERS material sitting on the coffee table hurt the sound.

I suspect one might be better off wrapping the transformer with mu metal, you know, something that absorbs the magnetic field the transformer produces.

Mu metal is not expensive, I'm guessing the same price per square foot as the Stillpoints stuff and can be wrapped around the transformer since it comes in thin malleable sheets that can be easily cut and also placed below and over the transformer. The issue of course is the powerful and toxic magnetic field produced by the transformer as a consequence of you know the current traveling through the wire, not to be confused with an electromagnetic field, that affects everything within proximity. One layer of mu metal absorbs about 75 % of the magnetic field, while two layers absorb about 96% of the magnetic field, which you recall from high school is orthogonal to the direction of the current flow.

Take care handling sheets of mu metal as edges are very sharp. I trim using those special shears that crimp the edges when you cut the sheets to help prevent cuts.

Ptss wrote,

"Are you saying the magnetic field from the transformer contributes as much noise as EMI/RFI?"

I'm saying it contributes more.

"Does wrapping with mu-metal cause any problems?"

Mu metal is conductive so one needs to be soemwhat careful. Usually the transformer is easily wrapped

"I also have a ~ 75 pound Equitech 2Q transformer. They don't appear to have it enclosed in mu-metal Any idea why?

My guess is either they don't know or don't care. I can't think of any manufacturers who enclose the transformer in mu metal. Go figure. Of course they don't do a lot of things, E.g., better fuses in, better power cords.

Never had luck with ERS, oh! well. Too phasey for me. But I did have good results with the 3M AB5100S on the AC cord coming into the player, on ribbon cables inside the player, those weird short 12 wire connectors, also on chips. Two layers of mu metal all around the transformer is noticeably better than one layer, but leave a space of say 1/4 between layers. I also strongly recommend pure natural cork 1/8" thick under any transformer and remove the bolt or at least loosen it. The bolt is a good idea only for shipping. It couples the 60 Hz hum to the chassis. Hel-loo! Finally, 1/8" cork spacers should be placed below all circuit boards. You know, to isolate them from the stupid transformer.