Hi Adamlau, I'm an audiophile not an ee, but there are lots of those products out there now - some pricey, some not - but I'm not so sure many are based on solid reasoning...most seemed to be based on what passes these days for conventional wisdom and most manufacturers themselves don't seem to be in any hurry to correct any false assumptions among their client base IME, assuming they even understand them. If you want MY 2 cents, first you need to choose your material carefully: Any ferrous metal creates inductance, a choke point at the point of install, the worst. Then there's plastic which allows too much static build-up, possibly better but still not good (btw, all of these ideas hold true for the recepticle box as well as the cover). Carbon fiber creates excess inductance at certain frequency ranges. This can be useful in certain applications (like in certain types of low-level digital circuits), but is detrimental in AC power applications, this is not much better. To make things worse, they can be agregiously expensive (as certain metal types can be as well). About the only commonly available material left is wood. Wood does not retain excessive amounts of static, doesn't ring like metal and maybe most importantly also doesn't exhibit any electrical anomalies since it is an insulator. The only problem with wood is that it vibrates. But, some species vibrate less than others and if you make a good selection there you're halfway home. There's Ebony, but it's both hard to find and pricey. Among the most commonly available ones in the US, maple may be the most sensible choice (provided it is the yellow, softwood variety found mainly in the homeland as opposed to the, harder, white varieties found in both the US and Canada). However, that said, the BEST-performing choice for Hi-Fi applications may be the ones sold by Waipuna Sound. These are made of Oregon-grown myrtlewood and are known to sound better in this application than maple. Cost - about $35(if I remember right) per cover. As I understand it, the vibration will "flavor" the sound (mainly through the midrange) - this flavoring will tend to be either large in amplitude or amusical, or both, if the species of choice is unflattering, or, either smaller in amplitude or more musical in character, or both, if the choice is a good one. But, there's just one last step, regardless of wood choice. The vibration will necessarily be influenced by the duplex-cover screw itself. This screw should never be over-tightened in this application as it will tend to close down the sound in the upper mids and highs. Instead, just arrive at a medium (finger-tight) setting and you will be much closer to the mark. You'll notice in some situations you'll be able to dial the sound in by ear to your preference, but in any case it will result in a noticeable improvement to the sound. But, I say stay far away from the majority of the "designer" options as these strike me as groups of folks who've figured out that customers in doubt tend to spend more money on Hi-Fi than is necessary to achieve good and solid performance. Hope this helps. If you still have any more questions for me and I haven't checked back for some reason, you can always email me.
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Not audiophile faceplates in my case, but non-magnetic receptacle cover plates over wire nutted hot/neutral serving as RF/EMI blockers. Regarding ISOCLEAN alternatives, found very little, decided to just go with Safety 1st plastic plugs regardless of static electricity buildup potential. I'll replace them with ISOCLEAN caps sometime down the line...
I must say that Joe Cohen once did a demonstration of a very substantial aircraft aluminum wall plate and similar surround over the wall plug of the pc that was shockingly better. I never bought it, however.
I did buy the IsoClean wall outlet. I also found that a single Acoustic Revive QR-8 in the center face greatly improved it. I now merely put a QR-8 in the center of the existing plastic wall plate and find it improves the sound somewhat.
(they are all off pigtails)
What wiring method was used for making up the pigtailed joint/s?
Wires twisted together then soldered and taped?
Cheap plastic wire connectors? Wires twisted together or wires just group butted under the wire connector?
Spring wire electrical connector, such as Scotchlok* brand?
Wires first twisted together then connector installed?
Wires grouped together, not twisted, and connector installed?
All can make a difference in wire contact line resistance.
What wiring method was used to make up the equipment grounding conductor?
Worst is the crimp only ground wire connector.
I have five unused receptacles in a dedicated 20A room circuit (I built the house and am a GC). Was considering removing them (they are all off pigtails) in an effort to reduce overall resistance through the circuit and placing brass cover plate over the openings.Not sure you will gain any benefit by removing the unused receptacles.
As for using a brass blank plate instead of plastic or nylon, again I see no benefit.
If you were connecting your audio equipment to one of the unused receptacles then yes the receptacle cover plate can make a difference.
As for using a brass blank cover plate to control RFI/EMI, that might control air borne RFI IF the electrical branch circuit wiring is installed in metallic conduit and a metal box.
If the wiring in the walls is NM-B sheathed cable,(example Romex*), I see no benefit what so ever. And if the wall electrical box is made of plastic the conductive brass plate could do more harm than good.
If the electrical box is plastic by NEC code the brass plate would have to be connected to the equipment grounding conductor.
The new faceplates sold at Cruze First Audio is by far the best I have ever tried...period ! I have some of these on all my Maestro ac outlets and these these two products together let you hear.. "recorded music like it was meant to be heard" !!..
These Brushed Aluminum Cover Plates are treated with the same RFI/EMI rejecting compuend used in the Maestro ac outlets !