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About a year ago I put in two 20 amp dedicated circuits, a cheap and easy upgrade that really did live up to the advertised improvments in my system. I have a question for the electical engineer types that may be lurking on the forum. The last three feet of romex that feeds my amp is coiled like a phone cord before it connects to the outlet. I don't remember where this suggestion came from, but it's ment to soften spikes and act as a surge protector of sorts. Lately, I've been questioning the efficacy of this arrangement. My main concern is that this may present a fire hazzard and to a lesser extent that it may reduce current flow. I've been thinking about this lately and figured I'd throw it out to this forum for any thoughts. I'm very happy with my current system and my house hasn't burned down yet, but you know how it is when you start thinking and the "what ifs" start swirling around in your head. If no one is concerned about the potential hazzard of this arrangement I'd love to hear of any possible improvements one might make to my coil. Maybe it should be wrapped around a core? What would you use for the core? Longer? Shorter? I have no idea, I'll try things that make sense to me, some work, some don't. All thoughts welcome. Herb
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Herb -
3 feet of romex coiled like an inductor is not good, IMO. And don't add a core!!! Personally I would unwind the coil if possible. A coil develops high voltages when the current through stops instantaneously, like turning off a power amp or you whole system. It could cause voltage spikes.
A dedicated line is fine, but a quality power line conditioner is more important. I use the PS Audio power conditioners, which do a good job of noise filtering. They can be expensive though. They make some smaller less expensive ones that work well. I'm sure others on the forum can name some quality less expensive ones if you don't have that already.John
unk:
"Why can't we all just, get along?" ~ Jack Nicholson (Mars Attacks)
My Website (hyperacusis, tinnitus, my story) -
I'm an electronics engineer, but not an electrician. To me it just sounds like a silly thing to do (no offense intended), but that's because I wouldn't expect it to actually do anything. I don't think it would hurt anything either, because the inductance is probably negligible.Comment
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Hmmm... air core long solenoid, maybe 1" in diameter and 3" long?
Yep Mark.... I agree...
Might have 20-50 uH there!!! Notice I said micro, not milli! Which might have a little effect on RF, but nothing to speak of at audio, and most surges are comparitivly slow enough for that to do much. The extra resistance is probably smaller than your existing power cord, also too small for noticeble effects.
It is a long amount of wire that dosen't have to be there... that much more area for an insulation breakdown someday, 20 years from now. If you want more RFI and surge suppression, get a filter or good power strip. I'd take out the slack and use it for in box interconnect wire on the next project... :BComment
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Well, I've always been an alarmist.
Okay, I thought he meant the coil was 3 feet long! But, I guess he only meant the actual wire length.
Actually, the coiled romex should have no affect since it contains both Hot and Neutral wires in the same cable. So the opposite currents should cancel out the magnetic field, I think.Johnunk:
"Why can't we all just, get along?" ~ Jack Nicholson (Mars Attacks)
My Website (hyperacusis, tinnitus, my story)Comment
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Yeah, I just don't see there being enough inductance there to really matter. And as JohmLoudb points out, relative to current flow, the return wire is wound in the opposite direction effectively canceling out inductance in the hot line.
Just to make sure, when you say 'coiled like a phone cord' you don't really mean a coil of wire, like wire wrapped in overlapping loops, but wire wound in a long spiral. So is this three feet of wire in a spiral, or is it a longer length wound into a three foot spiral?
Keep in mind that as coils go, this would be a very loose coil of wire.
I really don't think it matters.
Steve/bluewizardComment
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SILLY ! :rofl: :rofl: :rofl: Absolutely no offense taken, actually, the reason I asked the question was my own consideration that this arrangement was meaningless as far as positive effects while maintaining the possibility of introducing negative ones. As it is, it doesn't seem to do anything, but I guess I'll only know for sure after I remove it, as the loop has been it place since installation. The coil is about 3 feet of wire in one inch spirals. Because My amp has always been plugged directly into the outlet, my only hope was that this would offer some form of surge protection. I think this idea came from a conversation with an electrical engineer at a cocktail party regarding high end surge / line conditioners. He claimed that a surge would not be able to make it through the coil. Thanks again HerbHerbComment
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What are your thoughts on this product from PS Audio?
I was thinking about buying a PS Audio Power Plant premier, but really question how much of an improvement, if any, it will make. My system seems to be dead quiet and the power from the dedicated lines seems to be very stable. Yesterday, I hooked up and watched a multimeter for about an hour, and my voltage never varied more than volt. It bounced between 120.5 and 121.3 and never more than a 10th of a point at a time. The only thing in my house that seemed to effect it was my furnace cycling on when it took a momentary dip to 117.HerbComment
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Hmmmm....My house seems to run 125 ACV regardless of load. Good or bad?Lee
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Doesn't seem like you need anything except .......Originally posted by Herbonbay
Balanced power.......
Chasw98, myself and others use these....
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-BressonComment
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Mine too. I have a transformer with multiple taps that can lower the voltage to 120. Not sure it actually provides an audible improvement, but I sleep better at night....Originally posted by Alaric
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-BressonComment
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That would be good. I've used various PS Audio products like that, even with high power amps.Originally posted by Herbonbay
This might also be of interest to you, it has 2 "zones", like one zone for power amp and one for other components. Or, one for digital, one for analog.
PS Audio Duet
I had bad experience with power line noise. A high quality amp I bought was sensitive to the noise in our power line. And this noise would hurt our ears even at low volumes. After a lot of experimenting we found that it was some noise from the power line, and a power line filter solved the problem. I still use this amp and am very happy with it. It had great noise specs too, but it definitely needed a power line filter, at least with our power. Maybe it was ground noise.
A balanced line like Thomas suggested is good at canceling noise. I tried to build a balanced line using a shielded 1.5KVA transformer, but unfortunately the transformer I used had a loud hum. So I never finished that project. I've got an extra transformer, so I'm going to finish it when I get a chance. I'd also use a power line conditioner with the transformer.Last edited by Johnloudb; 26 January 2009, 19:18 Monday.Johnunk:
"Why can't we all just, get along?" ~ Jack Nicholson (Mars Attacks)
My Website (hyperacusis, tinnitus, my story)Comment
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If you really want to protect electronics, the best thing to do is have a whole-house surge arrestor installed. I would do that before any other protection measure.Comment
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