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Based on what I've read so far, a good sounding outlet should have all metal parts made of brass. That includes the metal strap which attached the grounding screw. I've found that all-brass outlets are hard to find. Most of them have straps and clamping plates made of steel. But I've already bought a few of them by mistake.My question is, does the steel strap have any degrading affect on the audio signal if I don't connect the grounding screw?
Follow Ups:
It depends on whether the outlet is mounted in a steel, nonferrous, or plastic box.For any type of box, the strap (very cheap outlets do not have one) is a steel or brass rod in the middle of the hot and neutral wires. Steel has a nonlinear magnetic response and acts like the core of a one-turn inductor. This inductor is in series with the AC voltage and causes distortion in the current from the nonlinear magnetic behavior of the steel. The magnet trick bartc mentioned helps by biasing the steel into a more linear region of its magnetic response curve, so that it produces less distortion. A better solution is to use an all-brass outlet.
For conductive boxes (steel or cast nonferrous alloy), the strap forms a conductive loop with the box that again is coupled to the hot and neutral wires because they pass on either side of the strap. This is a one-turn, shorted transformer, and a steel strap outlet in a steel box will have similar nonlinear response issues. A brass strap in a nonferrous alloy box will still have some effect. The simplest thing to do is to break the loop at one end of the outlet by using a Nylon screw and washer to prevent electrical contact and create a magnetic gap. The other end of the outlet should be fastened with a metal screw to properly ground the box, or you can wire a separate ground pigtail to the box.
The steel screws used on the outlet are also problems and should be replaced with brass or nonmagnetic stainless steel.
Thanx for providing such detailed information. I guess it won't matter whether I use ground connections or not. More dumb questions, is it necessary to use nylon screws for on-wall installation? Is the washer also made of nylon? Will an IG outlet make a difference?I also have one DIY'd Bell 5324 single gang box made of aluminum with a Marinco/Leviton outlet installed inside. How about the screw which tightens the outlet cover? Does it need to be nylon or brass?
And there's a debate with outlet covers, too. Should I replace my steel ones with brass or nylon? Some salesman told me steel covers would sound better than nylon, brass would sound better than steel, and aluminum is better than brass. Go figure. I hope I'm not alone in this outlet material madness.
The Nylon screw/washer trick is used for any installation where the box is metal, whether in the wall or in a power strip or box. The idea is to use one Nylon screw and washer and one metal screw, to preserve the ground connection to the box, but to break the loop formed by the box and outlet ground strap. The strap is electrically connected to the box through the metal screw, but there should not be electrical contact at the other end with the Nylon screw. The washer is to make sure of this and to provide a little air gap for the magnetic field. You can find #6-32 Nylon screws and washers at Home Depot or similar stores, in the massive Wall-O-Hardware bin section.Your aluminum box device should have a metal screw to ground the cover plate if it is metal. Just be sure the cover plate does not complete the circuit between the outlet ground strap and the end of the outlet that is insulated with the Nylon screw: a little tape on the underside of the cover plate at this end may be all you need.
There has been a lot of debate and experimentation on cover plates. Using no cover plate sounds better than almost any existing cover plate. IME, Nylon cover plates are almost as good. The best is a home-made carbon fiber slab with holes painstakingly machined to accommodate the outlets and cemeted to a plastic cover plate with epoxy. This is similar to the Oyaide design, and the carbon fiber material serves to damp standing waves on the power cords.
Metal cover plates reflect RF on the power cords and help sustain standing waves. Nylon plates allow RF to pass through and be reflected by the internal metal of the outlet and box. Carbon fiber is resistive, so it absorbs energy and damps standing waves.
Be very careful about putting anything inside an outlet box, as the corners on a ceramic magnet may cut the insulation on the wires. If you wish to proceed, get some rectangular ceramic magnets from Radio Shack that fit on the outlet strap. Secure them with polyurethane construction adhesive, and this will damp the strap against acoustic vibration as well as bias the steel's magnetic response.
An isolated ground outlet is only useful where you have armored cable or metal conduit with an insulated ground wire inside feeding a metal box. The armor or conduit will serve to ground the metal box, and the insulated ground wire will ground the outlet. The two grounds are connected at the circuit breaker box, but not at the junction box. This provides a method of shielding the power wires and equipment AC ground. It is still a good tweak to use one Nylon screw on such an outlet, as the metal loop comprising the outlet strap and metal box still exists.
You'll be famous if you have a website like Jon Risch's. As for the cover, I guess I'll leave it as it is. I'm a lazy tweaker and probably will dump all my steely damned outlets for those brassy babes.
I have seen some say it makes a difference, but I have been unable to hear any difference in my setup.
What you said worries me, too. But hell, it's a cheap tweak. The worst it could do is to prove that I'm just deaf afterall. This does not mean the same result will apply to you. Cheers.
Keep in mind, the backstrap is tied directly to ground. Hysteresis is only critical in the hot and neutral legs IMO.
Because of the basic construction of all USA outlets (except the 39-cent variety, without any backstraps), the backstrap is the core of a one-turn inductor formed by the hot and neutral wires. If it is steel and has hysteresis, it will induce a nonlinear reactive voltage that appears in series with the AC source.
Hogwash. What you have is the power coming in at a right angle to the back strap on the hot leg, and very little on the neutral leg. Your scenario would require significant current flow on the neutral leg to create a inductor of any consequence IMO
opposite in direction.The ground current is zero (unless there is a ground fault). There is nowhere else for the current to go.
IME steel backstraps are far worse than a couple of steel clamp down screws, but I have no scientific theory for this other than what's in the electrical/dielectric field.If you have the steel (or if your magnet shows that the yellow metal is really ferrous plated with something( here's a trick Al Sekela taught me: attach some ceramic magnets (ordinary Radio Shack stuff and cheap) to the backstrap, cover with electrician's tape or anything that will thoroughly prevent shorting if it touches wiring. This does something for "eddy currents" in the steel and you'll be able to hear the difference.
Thanx for the advice. I thought steel clamping plates and screws are in actual contact with the wire. Therefore they should have more direct influence into the audio signal.It's too bad that outlets are so difficult to disassemble. I almost dismantled one just trying to remove the screws.
BTW, does the magnet trick apply to IG outlets as well? Does the size of magnet make much difference?
Al's answered your questions, and you can take his advice to the bank!As to the cover plate thing, I've experimented and would concur with Al. We did some common experiments. But I do like some ceramic plates and the cast aluminum outdoor plates for mechanical damping with carbon fiber over them on the outside and UL rated foam type products for mech damping on the inside.
Thanx again Bart. Not sure where I can find those plates you've mentioned. Too bad there aren't pictures to look at. I guess I'll concentrate my efforts on outlet tweaks for now.
I found the carbon fiber blanks on ebay. Can't seem to find them now, but they're an odd item. If you look up carbon fiber you get a gazillion hits so that doesn't work well. It's a hunt or you can just buy carbon fiber cloth and resin it into whatever shape or as a cover to the cover of your choice.As to the cast aluminum, they're at every hardware store as the outdoor type box cover. And ceramic covers are considered a decorative cover, but widely available too.
Bart, I've located some local sources that do stock carbon fiber cloth sheets. They are not cheap, though. The lowest are around $15 per 25cm X 25cm. Not sure about the thickness, ranging from .05mm to whatever. I'm thinking about using a nylon cover with a precut outlet-shaped piece of carbon fiber cloth fitting underneath.BTW, I saw some plastic covers that look like nylon covers. Are they equally good or I must make sure they're made of nylon?
CF is expensive! No doubt. I bought a batch at auction on ebay, or otherwise it would have been considerably costlier and TAP wasn't able to get it in stock at that time due to the worldwide shortage.I got the 1/2" thick aircraft blanks on ebay as well, but don't see the seller there anymore and he hasn't answered further queries. Not at all sure you need this, it's probably overkill.
I used the CF cloth in two overlapping layers (Moray James suggested this for better coverage) behind a nylon plate. Didn't use the plastic cover plates (they're about the same $1.50 apiece) because of advice here, but cannot vouch for any scientifically demonstrable difference. They are probably different as dielectrics, one being PVC and the other nylon.
For quick duty (and I've never changed it out of laziness) I just enveloped the CF layers in 3M clear packaging tape and taped that securely to the back of the plate.
CF in my case didn't cut very easily or neatly. Hope that you find a way to solve this. I suspect that if you use the proper resin to cure the CF cloth to your plate, then Dremel out the holes you need, it might work better, but I haven't actually tried that approach.
You can attach the CF to the front or the back of the cover, but it MUST be between the last metal source (box, plate cover, outlet metal) and your plugs in any case.
You will want to make sure that the CF is not exposed to potential shorting, as I"m told it can carry electricity. So if it ends up being exposed, then you'd better cover that part with electrician's tape. I did and this works, though it isn't neat looking.
than I thought. No wonder Oyaide charged $200 for their CF/Aluminum plate. Makes me curious what CF really does for outlets to sound good. Maybe it minimizes the RF interference better than any other materials? Since it works for the outlet covers, I would assume it might do as well for the metal covers on audio equipments such as amps and digital sources.
CF cloth is made to be embedded in resin, so that's what it's designed for. If you try to use it "dry", you have to have good scissors to cut it well. If you use it embedded in resin, then you need tools that will cut that kind of plastic PLUS the rather cut resistant fibers as well. The CF blanks were maybe 10+ layers at least and embedded in hard resin, so they were a real bitch to work with and needed extra hardened tools to do it.But you can do the project you want reasonably easily IF you just use good scissors and work with the material before resination, I suppose. Don't worry, it's not a project you will screw up unalterably in any case.
I don't doubt that Oyaide deserves what it can get for their R&D and special machining of low volume pieces. However, I don't have that kind of money to spend, and I can DIY, so I get double the enjoyment for 10% or less of the price. But that's my story, not necessarily yours...
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