Shielding components from EMI/RFI... Help please

I've been putting the finishing touches on reducing the effects of EMI/RFI by putting ferrites on things.

I've put some ferrites on power cords in the system (only on components whose performance is not affected by current draw).

I've also been wandering around the house, putting ferrites on things that dump RFI onto the power lines.

Question: Would it be effective, and is it safe, to put a ferrite on the GROUND WIRE of the system's dedicated AC line?

Bryon

Would it be effective, and is it safe, to put a ferrite on the GROUND WIRE of the system's dedicated AC line?

Hi Bryon,

I don't see any problem with that, although I have no idea as to whether or not it will provide a benefit. As you no doubt realize, what it will do is to raise the degree to which the the flow of currents that are at and above some frequency in the RF region is resisted. That should be no problem either under normal circumstances or under fault conditions that would require the breaker to trip.

Best,
-- Al

Update. Three things...

1. After further experiments with additional ERS cloth, placing it in every location I could think of, I have come to the conclusion that, in my system, to my ears, it is harmful more than helpful about 90% of the time. Some folks predicted I would say that. You were right. It has a tendency to make things sound strangely "muffled." I find that just as puzzling as my initial impression that, in my dac, it resulted in a slight improvement in sound quality. I have not yet removed it from the dac to see if my impression might have changed. That is certainly possible, especially in light of the extensive tweaks I've made to reduce RFI/EMI in the system since I initially installed the ERS.

2. I am happy to report that, with the loving support of my wife and timely medical intervention, I have overcome a three week addiction to ferrites. :-) There are now approximately 50 ferrites all over the house. I attached them to things that pollute the power lines, as well as to some of the cables in the system, including the ethernet cables. I did NOT attach them to the system's interconnects, speaker cables, or power cables. I must say, they really work, provided you don't put them in the wrong place.

3. Among my final experiments with ferrites was to create two RFI pigtails. They look like this. I attached one pigtail to the chassis ground of the Meridian G68 and a second pigtail to the signal ground of the amp (which was made easy because Pass includes a signal ground binding post on the rear of the amp, for reasons that are unclear to me). I have no idea whether the RFI pigtails make a difference. I probably should have posted this part in the thread on Magic. Perhaps someone can comment on whether the whole idea of an RFI pigtail is preposterous.

Bryon

Hi Bryon,

Re your three updates:

1)One possible explanation would be that where the cloth produced a negative result it might have been deflecting radiated rfi into sensitive circuit points which the rfi would not otherwise reach.

Another possibility is that at some locations the cloth reduced jitter that may have been euphonic. In Steve N.'s paper that I linked to in my post dated 2-8-12, he describes how jitter can sometimes be euphonic in character.

2)Good!

3)The signal ground post on the amp would be needed if a powered sub having speaker-level inputs were connected to the amp's outputs. Since the amp's outputs are balanced, its negative output terminals have a signal on them, rather than being ground, and so the negative speaker-level input terminals of a powered sub should not be connected to those terminals. A chassis screw can be used as a ground connection point on some amps, but not on your Pass because signal ground and chassis are not common. They are connected together through a power thermistor (thermal resistor).

RFI pigtails can IMO be placed somewhere close to the border separating the remotely plausible from the totally preposterous. Which is to say that I wouldn't completely rule out the possibility that under some circumstances they might have at least a miniscule effect. I would bet against it, though. You may find the comments by me and others in this thread to be of interest.

The pigtail shown in your photo differs from the kind that is addressed in that thread, in part because yours appears to wrap the wire around a ferrite. The ferrite would raise the impedance of the wire at very high frequencies, which would alter the frequencies at which any antenna effects might occur. Whether that would be for the better, for the worse, or would make no difference, relative to having no ferrite on the pigtail, is anyone's guess. My guess is that it would make no difference.

IMO.

Best,
-- Al