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In Reply to: How is it that power cords can make a sonic difference??? posted by KeithA on September 15, 2003 at 18:32:31:
How AC cords can affect the sound:
http://www.AudioAsylum.com/audio/cables/messages/13538.html
(This is essentially the same as what I have at the web site, at:
http://www.geocities.com/jonrisch/ac-cords.htm)
http://www.AudioAsylum.com/audio/general/messages/188129.html
Tests of a power cord on a digital recording system:
http://www.thuneau.com/MPC/
AC Power artifacts getting past a DVD power supply:
http://www.hometheaterhifi.com/volume_7_3/dvd-benchmark-part-2-audio-9-2000.htmlNow aside from all that I have posted/written already, I will address the other part of the issues with power cords, the "miles and miles" fallacy. Some folks contend that due to the miles and miles of power lines from the electrical utility generators to your home, tha the last few feet can not possibly amke any difference.
The very reason for the use of AC power, instead of DC power, lies in what is known as the "Eye-Squared-Are" (I2R) losses.
Using a very simplified analysis, for any given run of power cable, the power losses in the line due to the resistance of the power line, will be proportional to the current squared. Voltage drop will equal the resistance times the current.
With DC, these losses just continue to go up the longer the power line run is, there is no way to string power to a whole line of houses, the guy at the end of a long parallel power line run would not get the full voltage, not by a long shot.
With AC, the voltage can be stepped up with transformers, and then stepped back down locally. For long distance transmission, the voltage is stepped up to thousands of volts, and then at sub-stations, stepped down to hundreds of volts, and then just outside your house, it is stepped down to a 240 V center tap, and you use one or the other of the sides of the 240 V center tap for your 120V wall power.
The (electric) water heater or furnace and/or dryer use the full 240 V, hence the special plugs and dedicated runs from the panel.
Stepping the voltage up reduces the current, and this is what keeps the power losses down, and is why electrical power is transmitted using a high voltage AC system.
So what matters from a local perspective, that is, what is relevant AT YOUR HOUSE, is that there is a step-down transformer outside your house that is the local low impedance source for the AC power, and it is this low impedance step-down transformer source that is actually the 'beginning' of the AC power chain AS FAR AS YOU IN YOUR HOUSE ARE CONCERNED.
The wires run from the house panel to the transformer on the pole are typically much larger than the house wiring, and are of a reasonably low inductance geometry considering that they have not been optimized for this.
So the limiting factor for power delivery to your audio system tends to begin right at the breaker panel and is primarily concerned with the length of romex that exists, and with how many wall outlet push-in connectors it has passed through on the way to your audio system wall outlet, with some slight extension of the limitations out to the local step-down transformer.
This of course, should illustrate why the myth of "miles and miles" of power lines is just that, a myth born out of ignorance of the actual situation, and the oft repeated mistatements of some who have a hard time actually thinking about AC power issues, and what is going on.
This latter info rounds out some of the many reasons that AC power cords can make an audible difference.
Follow Ups:
You say:"So what matters from a local perspective, that is, what is relevant AT YOUR HOUSE, is that there is a step-down transformer outside your house that is the local low impedance source for the AC power, and it is this low impedance step-down transformer source that is actually the 'beginning' of the AC power chain AS FAR AS YOU IN YOUR HOUSE ARE CONCERNED"
This would indicate that the arguement for only concerning oneself about the last few feet of cable is valid only in US. In UK we have the full 240 volts from a substation several miles away where it is lowered from high voltage to 240. So, following you arguement, we have to upgrade the entire cabling from the substation to improve our supply. Sorry - wrong.
Your arguement against DC appears to be flawed also. No one is suggesting the DC should be used in place of AC for household supply - your point about the guy at the end of the street getting a lower voltage is correct, but irrelevent. DC can, and really should be used as a stand-alone source of power for hi-fi. Why use AC and convert it to DC inside the box if you could use DC to start with? It's the "convenience" of not having to deal with batteries that keeps AC king of the power supply.
If AC really was as bad as cable vendors claim, then equipment makers would simply use DC. Truth is that AC is not the devil you make it out to be. One of the best sounding rooms at the Heathrow Hi-Fi Show last weekend used no mains conditioners and OEM cables throughout. Now, cable vendors would have a field day in pointing out that the supply in an airport hotel full of hunderds of audio systems is poluted to the extent that results would be unlistenable to. Not so!
Peter
Your comments are helter skelter all over the place, but I will respond to this:
it is known that a 240 Volt system is less afected by the mains run AND the power cords.The US 120V mains system in most locations is fraught with dirty corrupted interference ridden power, and as such, responds to efforts to clean it up abnd tighten it up.
Jon
You now argue that US mains is far worse than UK's. I wonder why this should be? We use similar power stations, use a similar high voltage grid and transform down to domestic voltage for use in homes in a similar way. The UK has a similar cross section of consumers - industrial, domestic, commercial, etc. What's the logic in your assertion? If it were true, then why do we have as many "tweekers" here in UK, and why are there so many "experts" wanting us to part with our cash to improve our AC supply? I think you may be making excuses for the arguement of yours that I challenged!Here is the reply I sent to some other poor chap who found his outlay on mains improvement was not money well spent! Why don't we put more faith in the integrity and experience of Hi-Fi manufacturers. I don't know any who decry the state of the AC supply being fed to their equipment. Furthermore, as argued previously, if mains was considered such a problem by manufacturers, they (at least high-end ones) would surely stop using their present method of generating DC from AC and would use batteries with a re-charge circuit engaging when off or in standby?
Peter
- http://db.audioasylum.com/cgi/m.pl?forum=general&n=292125&highlight=cawson&r=&session= (Open in New Window)
Well Jon, you're at it again. Blinding us with Science, or is it Mumbo Jumbo? As my maths teacher at school used to remark to those who answered a simple question with a clever answer "True, but irrelevant". Your discussion of the virtues of AC over DC for supplying power to our houses is just wool over the eyes. You have a vested interest and make a good living from power cables. You have an answer for everyone who dares to suggest that mains is mains. As I said in an earlier posting in this thread, if high end manufacturers really thought AC was a problem, they simply wouldn't use it.Sorry about my views, and glad to hear you're back in harness after your accident.
Peter
HowdyWhere do people get the idea that Jon profits from making cables?
He doesn't sell cables. He does tell people how to make cables for themselves and charges nothing for the info.
He has a job unrelated to cables but still manages to spend a great deal of time trying to be helpful here. And posts like yours are the thanks he gets?
He tries to explain things to a mixed audience where some have very little background and others PhD's in the subject at hand.
Anyway, we all digress a little from the subject at hand at times, but often at least some people will learn something.
Some equipment uses battery power, but that has lots of obvious problems too, especially for those of us that keep our amps making sound 24/7 :)
Hi TedOK, I take on board what you say about Jon's "proper" job, but he has set himself up as a cable guru and, as I see it, tends to blind his readers with probably true but irrelevant information about the virtues of the crazy sport of spending daft amounts of hard earned cash on the last few feet of our mains supply cabling. If he is such an expert, I wonder why he doesn't make a living from this expertise. I notice that you have $300-500 cables! I wonder what cable there is between the back of your IEC sockets and the transformers ie the last few inches of AC. Most equipment will use wire no better than what's in the derided OEM cable.
Batteries can, of course be recharged without turning off your 24/7 equipment. You are surely not listening 24/7, so recharge them when you're at work, maybe? My point is that if AC is the monstrous evil we are led to believe it is by the likes of Jon, don't use it - use pure and simple DC and no cable at all, neither OEM nor $1000.
Only my thoughts, of course. It's what we listen to that really counts.
Peter
HowdyWhy do people spread such rumors about Jon (or others). I consider it irresponsible.
Jon doesn't sell cables, work for a company that sells cables or recommend expensive cables, read his posts and his site more carefully, he just recommends that people consider cables better than stock, gives some motivational arguments and makes some suggestions about how to build some.
I don't agree with all of his recommendations, but I don't agree with all of what any particular person says. I don't see him as setting himself up as a cable guru; I see him as sharing the experience he's gained in his life with others. Take it or leave it.
The cable that is inside the equipment is in a different environment that the cable that's outside. In so far as shielding is important in power cables this matters.
As to my cables, I know what cable is in my equipment do you? I also know what people think when they hear my system and I know that I enjoy it too. What do you care about how I spend my money? I don't tell you how to spend yours and neither does Jon.
Besides the links at the top of Jon's original post he was just pointing out that the 'miles and miles of wire vs. the last 6 ft.' is a fallacy. You are the one trying to read something else into it.
I was just pointing out that some of us (probably not most) don't have time for charging batteries. We could of course charge enough different sets of batteries while we are playing that when the ones we are using run low we have others to swap in, but I know that I'd pay more for than I pay for power cords to not have this inconvenience. I am home most all of the time and what work I do I do to music at home. I'm just pointing out that there isn't any down time in some people's system. I never claimed to be normal :) Yes there are some systems that are DC powered, but so far their prices are out of sight or have other inconveniences, etc.
Anyway your AC/DC arguments are red herrings, we all have equipment that requires good AC and whether it matters to you or not, it matters to some of us what power cords we use.
I would not presume to tell people what to spend their money on, but many seem to be carried away with the idea that mains is far worse than it is and that a "quick fix" of the last few feet will make a significant improvement.If it was just screening that makes the difference then screened AC cable is a couple of dollars a meter. My point about what's inside the case is more than simply the screening aspect. The wire itself is nothing special, beacuase manufacturers know it's really not that critical.
Battery powered equipment (except hungry power amps) can be easily built without the need for spare batteries or effort in recharging. When not listening, they can be switched to "recharge" whether or not you turn off the supply to the equipment. Simple as a regular On/Off switch, but reading Charge/Run or something. The reason most equipment is AC powered is simply that AC is in fact, a perfectly acceptable form of power and manufactures are quite content for its use in their equipment.
Let's agree to differ on this - I would prefer spend the thousands that some spend on conditioning AC on better equipment where there is a genuine payback.
PS I'm not suggesting that better cables make NO difference, but that a carefully designed screened cable of the type Chris Venhaus promotes (and Jon for that matter) will do all that's necessary. Spending more than the $50 or so (and that includes vast mark ups) is money not necessarily wisely spent. Those who believe the AC is so bad that several '000 are needed, should be looking to DC instead.
HowdyYou are still presuming that some of us didn't do as you suggested and then found that even better cords made more difference.
I first got dedicated lines that made a heck of a difference. Then I tried more and more expensive power cords and stopped when I got to an optimum. In fact many of the cords that were even more expensive than the ones I have sounded worse. I even used single blind tests on my daughter at each upgrade.
You also didn't read my messages very well. I never have any down time for recharge.
Oh, well. As you suggest our time is better spent listening to music than arguing.
Putting on my Moderator hat: don't spread more rumors here.
Hi TedWhat you say genuinely astonishes me. I can understand that unshielded AC cables in the usual tangle of wires at the back of ones rack is likely to upset signal cables, so I'm fully in favour of changing to screened cable. However, when you objectively consider what happens with the AC once inside the equipment, all this talk of megabucks cables makes no logical sense to me. Firstly as suggested before, the wiring between the socket and transformer is unlikely to be much better than what's in OEM cables. Then what happens? The AC goes into a transformer - hundreds of coils of copper wire doubled back on itself - the supply going in and out of the primary winding. This causes a fresh AC supply to be generated in the secondary coil, which has no physical or electrical contact with the primary. One wonders how imperfections in the AC cable can possibly adversely affect this new supply, now in the independent secondary winding. The rest of the equipment's power circuit rectifies, smooths and stores this secondary supply for use by transistors, valves, etc. In other words it tries to mimic a battery. Surely a well designed circuit can cope with an incoming supply deprived of a $1000 cable for the last few feet? As I say, it is astonishing to me that this should be the case and I would dearly like a logical explanation of physics I have may have missed.
I am happy though to believe that a decently designed amplifier is not adversely affected by a standard AC cable in the same way my washing machine washes just as well with an OEM cable as a $1000 one (OK I'm jesting, but you get the point!). Otherwise, as I have suggested earlier, manufacturers would not put up with grotty AC.
Incidentally even Maggie Thatcher, bless her heart (if she actually hadf one), admitted to spending 3 hours a night in bed. Plenty of time to recharge batteries!
I'm off to listen to music via my sub $50 AC cables - doesn't Eva Cassidy have an astonishing voice?
Peter
What you say about the internal transformer is only partial correct.
If it was a "perfect transformer" like those tault at college then you are correct. BUT in the REAL world with real components nothing is that simple. firstly there will be a coupling between the primary and seconday windings caused by the phyical spacing between them. ie they are capacitivly coupled, this will let through noise.
secondly the transformer core dependant on its material constuction, will also allow non 50/60Hz frequency coupling.
thirdly any RF on the line will travel on the outer surface of any metal, it can jump across the transformer and capactivly couple itself to the equipments DC line without too much problem.Since most equipment manufacurer dont "design their" equipment to any great degree of noise immunity or rejection (those that do produce broadcast quality suff at a large price multiplier), we are left with a far less than perfect ("it will do @ that price") level of equipment.
Hence we are left to the snake oil saleman, and the genuine engineer/designer, and ferrite rings, JR & CVH and others to try and solve the problems. This is one of the reason that so much discussion goes on about mains, and cables in general. The others are lack of indepth knowledge, arrogance, ignorance, pride, prejudice, stupiity or any of the other deadly sins.
Incidently the platting of any wire is known to reduce the noise level of a signal on it. Kimber and others have made a lot of money out of this known fact. and not a serpent in sight.
HowdyWell, not everyone is like you. I need sound to sleep. Otherwise other distractions keep me awake.
I, Jon and others have answered, or at least tried to answer your other questions. I'm an EE and fully understand where you are coming from and used to be just as sure of myself and just as wrong. Listen for yourself, things make a difference and everyone has different systems, preferences and pocketbooks. You don't seem to understand that the components we use don't exactly match their mathematical models. A good engineer understands the limits of their models and keeps an open mind when things don't work like the math says it should. Better engineers figure out what's wrong with the models, refine them and build better products.
Is adding a $1000 power cord the most cost effective thing to do? It depends on your budget, how much your time is worth, how much custom engineering you are willing to do or pay for, etc. I never claimed it was the best for you. You also may note, that I don't use $1000 cords myself, but I have friends who do and I sure as heck can tell the difference in their systems when cheaper cords are used.
Once again, the environment inside a unit isn't the same as outside, shielding is the most obvious difference. Also some of us have replaced internal point to point wiring with better quality wiring, others of us have bought components with high quality wiring already built in.
Ralph Vaughn Williams spinning here.
"This of course, should illustrate why the myth of "miles and miles" of power lines is just that, a myth born out of ignorance of the actual situation, and the oft repeated mistatements of some who have a hard time actually thinking about AC power issues, and what is going on."Respectfully, it does not illustrate why one should spend hundreds orf dollars (or ebven over a thousand) on a power cable when one can simply install a good line (ie. 10 gauge) from the mains to a dedicated outlet --make it isolated ground. Total cost about $100 plus electrician. And it can feed your whole system
The lossses attributable to the last 3 feet are negligible anyway.
HowdyEven with four #10 gauge dedicated circuits for my system, power cords make non-trivial differences. Unfortunately each device likes different cords. The good news for me is that the most expensive (> $1000) cords that I have tried sound worse to me than the more moderate priced cords (say $300 - $600) in my current system.
Your response completely ignores the aspect of the power cord either radiating, or picking signals from other power cords or any of the other cables, including video or digigtal feeds.This was touched upon in the referenced URL's. It might help to actually read them.
I am not ignoring that. You did yourself in your post. Read it again. You are arguing that the typical argument about long lines of cable before your expensive power cable is absurd, and then at no point do you say that the reason the expensive cable sounds better is because of RFI. Rather, you explain that there are losses between the mains and your outlet.Perhaps a fair point if you have a poor installation. But an expensive power cable is an asburd solution.
OK, now you raise the issue of RFI. Frankly, I have yet to read a single white paper describing how a particular power cable filters RFI that makes sense to me (sorry, I had read yours, as well as Caelin's, etc.). My experience is that with an adequate installation all well designed (not too hard) power cables sound the same. Please respect that.
My previously posted and referenced URLs commented on a great deal, of which radiated noise, RFi, EMI, etc were covered. Only in the test of the last post, this one:
http://www.audioasylum.com/audio/cables/messages/82423.html
do I only talk about the line losses ONLY.If the supplied post URLs do not make sense to you, then either I have failed at my laymen's explanations, or you are not geting it despite the layman's explanations.
I can respect someone's experiences, but that would have to include on your part having tried numerous power cords under varied conditions, etc., and having experienced a dedicated run on the same system, vs. the additional use of high perforance power cords, as well as having heard numerous power cords on other ssytems under diferent conditions.
Perhaps your mains are relatively clean, and you have really nice cable layout in back of your equipment. Regardless, your conclusions probably only hold for your system, and not necessarily for others.I have done the above with all types of audio cables and with power cords. Each system reacts differently, and some equipment seems relatively immune to power cord/mains issues, and each component reacts differently to different cords.
As for an "adequate installation" of the mains, this is the exception rather than the rule, and basing your statements on some utopian ideal is not very realistic.
You're absolutely right. There's a load of garbage spoken about mains. See my reply to Jon a few inches up the screen!
I know I learned more about power transmission from your post than I ever knew before.Thank you very much for taking the time to explain and, again, thanks to all who shed some light here. You guys are the best.
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