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Post by drumace on Oct 12, 2022 17:19:23 GMT -5
Hey folks, I’ve found a pure copper tape (double side conductivity) on Amazon that claims to help eliminating EMI noise (e.g. for guitar pickups). Has anyone tried using such product on cables (e.g. power cables) and had positive results?
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Post by 405x5 on Oct 12, 2022 19:05:12 GMT -5
Hey folks, I’ve found a pure copper tape (double side conductivity) on Amazon that claims to help eliminating EMI noise (e.g. for guitar pickups). Has anyone tried using such product on cables (e.g. power cables) and had positive results? Noise such as you describe is par for the course with electric guitar pickups, mikes on live drums and such. God forbid you would have to resort to such in home audio gear. None of today’s modern home gear should fall victim to such a thing.
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Post by Boomzilla on Oct 13, 2022 3:52:11 GMT -5
Magnetic noise, so far as I understand it, is usually 60 Hz. hum that is picked up form adjacent wiring and equipment. This is more common in stage applications due to the great number and close proximity of signal and power cables (and the proximity of transformers). The easiest way to protect against such hum (in order of preference for home audio systems) is to:
1. Dress signal and power cables away from each other to the extent possible 2. If distance between wires can't be increased, then try to cross the signal and power cables at right angles to each other (minimizing their interaction) 3. If neither of the above work, buy shielded signal cables to minimize hum pickup
Radio frequency (RF) noise happens at much higher frequencies, and can (rarely) have unpredictable effects on amplifiers. Again, this is more common in stage amplification due to the large number of lighting devices, many of which can emit RF. In home audio, it is usually caused by close proximity to a strong RF emitter such as a cell phone tower, radio station antenna, wireless modem, or CB antenna. Use of shielded cables is the usual solution. Some also recommend the use of "cable risers" that are non-conductive devices that prevent the speaker cables (usually) from touching the floor. The theory behind the use of cable risers is akin to the experience those of us who are old enough had with "rabbit ear" television antannas. When you'd touch the antenna, the reception would improve because your body was essentially becoming part of the antenna, and the greater surface area was more effective at catching radio waves.
The "cable lifter" theory is that if your speaker cables are in contact with the floor, the added antenna surface area (the floor) catches more radio waves. Cable lifters need not be expensive. I use 0.68 cent "rebar chairs" from my local Lowes store. Made of non-conductive polypropylene, a few of these will keep your speaker wires away from the floor.
Cheers - Boomzilla
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Post by 405x5 on Oct 13, 2022 7:59:15 GMT -5
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Post by Boomzilla on Oct 13, 2022 8:23:37 GMT -5
I don't ENDORSE cable risers - I just have been asked to use them by the company whose speaker wires I'm reviewing. I haven't tried them yet, but will comment once I have.
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Post by 405x5 on Oct 13, 2022 9:25:05 GMT -5
“The "cable lifter" theory is that “ As long as the “theory” is hanging around, this guy WILL be waiting….
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Post by audiosyndrome on Oct 13, 2022 9:54:15 GMT -5
Yes. Snake oil and Boom, as usual, doesn’t even have the right oil. 😜.
Russ
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KeithL
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Post by KeithL on Oct 13, 2022 10:08:59 GMT -5
Do you actually HAVE EMI noise that you can hear? If not, then "it ain't broke so don't try to fix it"... Old-style guitar pickups were not only very sensitive, but also handled very low-level signals, and operated at very high impedance. As a result they were about as sensitive to noise as the most sensitive high-impedance microphones. This made them very fussy about cables and very subject to both hum and pretty much all other sorts of electrical interference. They were also remarkably sensitive to cable capacitance... and tended to be very subject to high frequency response changes with different cables. Guitars were also often expected to work in stage environments, with lots of noise from light dimmers and other electronic gear, and long cable runs. And people would often "grab a cable out of the box" without ensuring that the cable they chose was RATED "for microphones". Unlike "plain old balanced interconnects" "microphone cables" have especially good shielding, tight twist ratios, and other features designed to minimize noise pickup. People also tended to be very sloppy about details like being careful not to run microphone cables parallel to power cables. Power cables are the exact opposite. They carry a low frequency waveform, at a very low impedance, and the gear they're connected to is usually quite immune to noise anyway. With power cables, if anyone bothers to shield them at all, it's mostly to prevent noise generated by the power supply from radiating FROM the cable, where it can be picked up by something else. The only exception is that some unusual gear is rather sensitive to high noise levels at certain frequencies that leaks into the equipment past its line filters. (Like when you can hear your neighbor's CD radio, or the buzz from your light dimmer, on your cranky old tube amplifier's outputs.) And, if so, regardless of any sort of power line filter you have, noise can get into the power cable between the line filter and the device. And, if that happens, you can spend an extra five bucks and get a shielded power cable. (Some of our power cables actually are shielded but offhand I don't even know which ones.) IF YOU HAVE A PROBLEM WITH NOISE ON YOUR POWER CABLES then using shielded power cables might not be a bad idea. But it makes no sense whatsoever to wrap a power cable in copper foil rather than simply to use a shielded power cable to begin with. Also note that, in addition to being silly, wrapping a cable in conductive copper is actually dangerous. (It's too easy for that copper to touch something, or for a loose edge to touch something, and short something out.) Interconnects are ALREADY shielded... either with braid, or foil, or both. And, if you have crappy interconnects, with poor shielding, then the solution is to buy good interconnects with better shielding. There are situations where foil shielding can be useful... But they are few and far between... And it absolutely is silly to wrap things in foil "as a preventative measure"... Hey folks, I’ve found a pure copper tape (double side conductivity) on Amazon that claims to help eliminating EMI noise (e.g. for guitar pickups). Has anyone tried using such product on cables (e.g. power cables) and had positive results?
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KeithL
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Post by KeithL on Oct 13, 2022 10:16:22 GMT -5
Cable risers on speaker cables and power cables are pretty much the ne plus ultra of snake oil... Although, to be fair, in most cases, they probably won't hurt anything. However, if you want to see if lifting the cables off the floor makes any difference... try toilet paper rolls... or pieces of paper-towel roll. (You cut little notches in the top end for the cable to sit in.) The cost nothing and absolutely positively will make as much difference as anything else - regardless of price. Or, if you want to get fancy, you can make them out of nice grey PVC water pipe, with notches at the top, and cute little pipe flange bases on the bottom. I don't ENDORSE cable risers - I just have been asked to use them by the company whose speaker wires I'm reviewing. I haven't tried them yet, but will comment once I have.
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KeithL
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Post by KeithL on Oct 13, 2022 10:26:35 GMT -5
Unless your floor is metal it isn't going to act as much of an antenna or a reflector. The usual claim I've heard is that what you're worried about is the capacitance between the speaker wire and the floor. (Especially with things like nylon carpet - which, for all I know, may actually be a relatively non-linear dielectric.) Of course it is all absurd... Magnetic noise, so far as I understand it, is usually 60 Hz. hum that is picked up form adjacent wiring and equipment. This is more common in stage applications due to the great number and close proximity of signal and power cables (and the proximity of transformers). The easiest way to protect against such hum (in order of preference for home audio systems) is to: 1. Dress signal and power cables away from each other to the extent possible 2. If distance between wires can't be increased, then try to cross the signal and power cables at right angles to each other (minimizing their interaction) 3. If neither of the above work, buy shielded signal cables to minimize hum pickup Radio frequency (RF) noise happens at much higher frequencies, and can (rarely) have unpredictable effects on amplifiers. Again, this is more common in stage amplification due to the large number of lighting devices, many of which can emit RF. In home audio, it is usually caused by close proximity to a strong RF emitter such as a cell phone tower, radio station antenna, wireless modem, or CB antenna. Use of shielded cables is the usual solution. Some also recommend the use of "cable risers" that are non-conductive devices that prevent the speaker cables (usually) from touching the floor. The theory behind the use of cable risers is akin to the experience those of us who are old enough had with "rabbit ear" television antannas. When you'd touch the antenna, the reception would improve because your body was essentially becoming part of the antenna, and the greater surface area was more effective at catching radio waves. The "cable lifter" theory is that if your speaker cables are in contact with the floor, the added antenna surface area (the floor) catches more radio waves. Cable lifters need not be expensive. I use 0.68 cent "rebar chairs" from my local Lowes store. Made of non-conductive polypropylene, a few of these will keep your speaker wires away from the floor. Cheers - Boomzilla
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Post by 405x5 on Oct 13, 2022 10:30:05 GMT -5
It’s been 51 years since I’ve had to contend with any sound coming from the loudspeakers other than music. Modern equipment has made short work of that by default.
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Post by Boomzilla on Oct 14, 2022 4:23:44 GMT -5
Unless your floor is metal it isn't going to act as much of an antenna or a reflector. Well, when I touched those rabbit ears, reception DID improve - and I'm definitely not now nor was then "made of metal." I'm sure you've plausible explanations of why the rabbit ears and speaker cables aren't the same, but every once in a while I must question your expertise... After all, there IS a lot of metal rebar in a concrete floor, and the inverse square law works all the way from audio frequencies up to gamma radiation. ...Of course it is all absurd... Maybe it is, maybe it isn't. Have you ever actually tried it? If you believe nothing but measurements, Amir at the Audio Science Research website can easily "prove" for you that a $110 Topping D-10S DAC sounds better than the Audio-GD DAC ("One of the worst DACs ever tested"), yet nobody who has actually listened to the two would conclude that. I"m becoming less willing to rely on others' measurements or claims (particularly for those who haven't actually HEARD what they're dismissing) as to how a thing sounds. I do, however, trust my own ears. Are cable risers "snake oil?" I'll say once I've tried it. You don't have to believe what I hear. But I do my best to honestly say what I do and don't hear. And I won't call any claim "absurd" based on what I THINK I know about it. Boomzilla - aka Glenn Young
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Post by ttocs on Oct 14, 2022 8:39:34 GMT -5
Regarding copper shield foil tape for a guitar, consider that the foil is to shield the pickups and controls from extraneous signals "entering" the guitar. It's not for shielding the wires connecting the pickups and controls.
Cable risers? Now when we talk about cable risers, this is one of those things that may help some, but not all. When I first learned that these existed I laughed, but when I considered what effect carpet can have on things it seemed to make some sense. I have wood flooring so I'm not concerned about any static charge buildup as such.
Also consider how a building might be constructed and what that construction is hiding. Where I live, all electrical is in metal conduit and boxes, so that's one level of shielding which helps greatly, so while I do avoid running speaker wiring and interconnect cables close to conduits, it's not like trying to avoid Romex.
Then consider dielectric. This is an interesting concept. There are speaker cables which try to use nothing but air as a dielectric, so this means that these cables really need to be kept away from all surfaces, because everything has a dielectric quality of some sort. So when using different speaker cable designs, the LCR values change. When I measure LCR of a cable, some values change depending on if the cable is hanging in air, or laying on the floor or granite countertop. This is when a cable riser can be used, but might not always be of value to the user. It's another tuning device.
I bought two kinds of 3-wire cable from the home store to use as power cables, one was by mistake. The only difference is the dielectric thickness. The thicker one is rated at 600V, while the other is rated at 300V. I want the thicker one because it limits the interaction of a wire carrying 120VAC from a signal wire, not because it is safer to use when passing 600V through it. But it makes a difference. The proof is written right on the cable as a UL certification that the dielectric does something, all by itself.
And like Keith pointed out, a cable riser can be made with just about anything, but, some materials may have an unwanted effect.
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Post by mgbpuff on Oct 14, 2022 14:13:02 GMT -5
IF your speakers are significantly out away from the walls, cable risers just make the installation look nicer. That's the only reason I would use them. As for copper tape DIY shielding - that's just plain dangerous; don't do it!
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KeithL
Administrator
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Post by KeithL on Oct 14, 2022 14:18:15 GMT -5
At the frequency and characteristic impedance of TV broadcast signals your body has significant inductance, capacitance, and inductance. So, by touching those rabbit ears, and even by moving exactly where you touch them, you are tuning the resonant properties of the antenna. And, yes, at those frequencies and impedances, you are also a conductor, and so an antenna. And, yes, wrapping copper foil around a length of twin-lead TV antenna cable, used for TV reception, will make a HUGE difference. (And, in that situation, coiling up a few turns of spare wire, or even a single sharp bend at a corner , may well cut your signal strength significantly.) However that is all quite different than the frequencies and impedances that apply to AUDIO signals. The whole point is that, while the inverse square law also works for gamma radiation, we also know that gamma radiation is inaudible to humans. (As well as for any other sort of organic life form I know of.) Amir CANNOT prove that one DAC sounds better than another. He has never done any studies to determine which specifications result in audible differences - or to what degree. What he CAN prove is that one DAC has one or two specific measurements in which it compares favorably to another. He then chooses to assume that those are the only specifications that affect "sound quality". And that is a rather different matter. The other problem is that we are limited in our range of options.... To be quite blunt there are dozens of things that could be wrapped around a cable to potentially shield or protect it from various external influences. Likewise, you could space it away from the floor, at various distances, using various materials, and from different floor materials. But, being of limited time and resources, we are limited in how many of them we can take the time or effort to test. Therefore it makes sense to only bother to test those that have a reasonable likelihood of doing something useful - based on what we know. To pick an absurd example.... Based on the available information, lifting a speaker off the floor is as likely to make it sound different as wrapping it in wet dog fur... (Before you make a face I will remind you that there are companies who sell very expensive cables "insulated with hand woven organic cotton".) At the very least you should try spacers of different lengths, made of different materials, and of different shapes. After all if a spacer makes a difference, then perhaps there is a difference between a Teflon spacer and one made of ABS plastic or ceramic. I could also list a dozen other things you could do that would be equally likely to make a difference... So are you planning to try all of them? Personally I'm going to go with the science... which suggests that none of them is likely to make a significant and positive difference. (And, to be very blunt, life is far too short to waste time on the ones that are especially unlikely to make any difference.) Unless your floor is metal it isn't going to act as much of an antenna or a reflector. Well, when I touched those rabbit ears, reception DID improve - and I'm definitely not now nor was then "made of metal." I'm sure you've plausible explanations of why the rabbit ears and speaker cables aren't the same, but every once in a while I must question your expertise... After all, there IS a lot of metal rebar in a concrete floor, and the inverse square law works all the way from audio frequencies up to gamma radiation. ...Of course it is all absurd... Maybe it is, maybe it isn't. Have you ever actually tried it? If you believe nothing but measurements, Amir at the Audio Science Research website can easily "prove" for you that a $110 Topping D-10S DAC sounds better than the Audio-GD DAC ("One of the worst DACs ever tested"), yet nobody who has actually listened to the two would conclude that. I"m becoming less willing to rely on others' measurements or claims (particularly for those who haven't actually HEARD what they're dismissing) as to how a thing sounds. I do, however, trust my own ears. Are cable risers "snake oil?" I'll say once I've tried it. You don't have to believe what I hear. But I do my best to honestly say what I do and don't hear. And I won't call any claim "absurd" based on what I THINK I know about it. Boomzilla - aka Glenn Young
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Post by 405x5 on Oct 14, 2022 15:12:42 GMT -5
The ONLY cable riser that REALLY works
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Post by audiosyndrome on Oct 14, 2022 17:01:03 GMT -5
Unless your floor is metal it isn't going to act as much of an antenna or a reflector. Well, when I touched those rabbit ears, reception DID improve - and I'm definitely not now nor was then "made of metal." I'm sure you've plausible explanations of why the rabbit ears and speaker cables aren't the same, but every once in a while I must question your expertise... After all, there IS a lot of metal rebar in a concrete floor, and the inverse square law works all the way from audio frequencies up to gamma radiation. ...Of course it is all absurd... Maybe it is, maybe it isn't. Have you ever actually tried it? If you believe nothing but measurements, Amir at the Audio Science Research website can easily "prove" for you that a $110 Topping D-10S DAC sounds better than the Audio-GD DAC ("One of the worst DACs ever tested"), yet nobody who has actually listened to the two would conclude that. I"m becoming less willing to rely on others' measurements or claims (particularly for those who haven't actually HEARD what they're dismissing) as to how a thing sounds. I do, however, trust my own ears. Are cable risers "snake oil?" I'll say once I've tried it. You don't have to believe what I hear. But I do my best to honestly say what I do and don't hear. And I won't call any claim "absurd" based on what I THINK I know about it. Boomzilla - aka Glenn Young Boom - you’re questioning Keith’s expertise? Now you really look foolish. Please leave the tech talk to people who know what they’re talking about. Russ PS Amir never said a Topping DAC sounds better than an GD Audio DAC. He may have said “it measures better”. You don’t even comprehend that. 😜
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Post by Boomzilla on Oct 15, 2022 11:01:25 GMT -5
OK - Let's cut to the chase: I agree that KeithL is an expert on all things audio and does know far more than I on every audio topic. HOWEVER, I am also in the middle of a cable review for a major cable manufacturer and am in direct contact with the gentleman who designs the cables. The company is one of the largest in the audio field, and offers speaker wires in every price category. The designer says about cable risers: "Cable risers reduce the amount of RF noise that capacitively couples into the speaker cables through all solid flooring materials. Successfully designed and properly used, cable risers will preserve valuable low-level detail for more natural, dynamic, involving performance." Yes, it IS "advertising speak," but there is no ambiguity. He recommends cable risers - KeithL doesn't. Now neither KeithL NOR the cable designer sells cable risers, so neither has any financial motivation to lie or exaggerate. So I now have two experts telling me diametrically opposing things. Which "expert" is to be believed? The easiest solution is to listen for myself and then report what I hear. And in spite of the fact that not even experts agree on this topic, I still have to contend with ignorant yahoos trying to tell me how foolish I look and how I know nothing... Go figure. Glenn Young (aka Boomzilla)
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Post by JKCashin on Oct 15, 2022 11:24:13 GMT -5
Wouldn't RF noise be outside the frequency range that we care about?
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Post by Boomzilla on Oct 15, 2022 11:32:38 GMT -5
Wouldn't RF noise be outside the frequency range that we care about? I'll let KeithL answer that one. The simple answer is "yes, RF noise is outside the limits of human hearing." But... Some amplifiers may be sensitive to having RF at their outputs. If the amplifier is affected, the audio band may suffer.
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