Nordost Valhalla AC Power Cables, I've been reading a lot about them... Options

[Funkstar De Luxe]

It seems these AC cables are being praised in just about every HI-Fi magazine I pick up. Aparently they provide better timing (no, I don't know what that meant either), better dynamics and deeper bass. At $2500 a piece they better had.

I'll get to the point now. I don't understand why the cable to the power supply in the component (amp, CD player etc) would have any effect on the sound. The electricity runs though all different kinds of crap cables to get to your house and somehow placing 2 meters of very expensive cable at the end of that chain make a different? I don't think so. Sure, good quality cable to hook everything up is vital - after all it's your actual audio that's runiing though them. But an audiophile mains lead?

Can some one please tell me a logical/scientific explanation of how this works? Is there one? Anyone actually heard the difference a good power cord caqn make to their system? It seems like a load of shit to me but there is just too many reviews and publicity for it to be completely false.

Tony

[jaustin]

Can some one please tell me a logical/scientific explanation of how this works?  Is there one?  Anyone actually heard the difference a good power cord caqn make to their system?  It seems like a load of shit to me but there is just too many reviews and publicity for it to be completely false.

I think it's impossible to answer part of your question without violating TOS #8. But I'll try to answer the part I can answer by quoting the available reasonable arguments, none of which I have verified. IMO, in audio there's very little you can rule out on the basis of simplistic technical arguments. A/C power cords are a case in point. Still, $2500 power cords are absurd and completely unjustifiable.

Do they make a difference in the sound? Sorry, can't anwer that (TOS#8). Is it possible that they do? Absolutely. Expensive power cords can, in principle, act as filters for high frequency nasties on the power lines. These nasties are often generated by digital equipment, sometimes in your stereo system. CRT computer monitors are also very bad. The worst source in my house is a cheap range with a digital control panel. A cord with a ferrite-impregnated jacket can act as a filter for high frequencies. I'm not claiming that the cord you mentioned actually does this, but it's possible. Also, heavy shielding can reduce the nasties that could get into the supply via radiation, via the cord acting as an antenna. It's well documented (see, for example, the classic book by H. Ott) that such nasties can adversely affect the operation of various types of electronic equipment.

Another factor is that by modeling an typical amplifier circuit you can see that the peak current in the power cord far exceeds the RMS value. That's because the power supply only "recharges" at the top of the A/C cycle. You can get some rather intense current peaks, exceeding the RMS value by a factor of 10 or 15. The result can be a very significant reduction in voltage as a result of resistive losses in a typical 18 gauge power cord and its associated imperfections (poor crimps, etc.). These very fast current pulses can also create high-frequency nasties, which can feed back into the A/C in the absence of shielding and filtering.

Those are (some of) the arguments, and I find them reasonable, though they certainly don't justify paying $2500 for a power cord. I don't know electronics that well, but I have a physics Ph.D.

Jim Austin

This post has been edited by jaustin: Aug 3 2004, 19:25

[WmAx]

Those are (some of) the arguments, and I find them reasonable, though they certainly don't justify paying $2500 for a power cord. I don't know electronics that well, but I have a physics Ph.D.

This all comes down to basic electrical/rf laws, though. The hi-end proponents specifically make their claims on supposodely 'mysterious' or 'unknown' variables. But any properly designed audio applanec should have an effective filter in the power supply. Personally I would question the value and engineering of audio equipment that required a special pwer cord that had special filtering properties in order to function properly.

-Chris

[jaustin]

This all comes down to basic electrical/rf laws, though. The hi-end proponents specifically make their claims on supposodely 'mysterious' or 'unknown' variables. But any properly designed audio applanec should have an effective filter in the power supply. Personally I would question the value and engineering of audio equipment that required a special pwer cord that had special filtering properties in order to function properly.
-Chris

True, it all comes down to electrical/rf laws, but I don't know about "basic". Finding the answers to some of these questions would require careful experimentation and possibly modeling. As for questioning the value and engineering of audio equipment that requires a special power cord to function properly, I agree with you up to a point. There's some very expensive, very poorly engineered equipment out there. But I'm less inclined towards the polarized view this implies: good engineering wouldn't benefit at all, lousy engineering might. There's a lot of middle ground here between great and lousy, and many widely available products may fall in the middle...and consequently may benefit the extra filtration/reduced losses an aftermarket power cord might provide. There are some easy tests you can do, though visual ones are often easier than audible ones. Try using a good A/C filter on your television while watching a DVD. If your power is clean you may not notice a difference. But if the power isn't clean ... If A/C nasties can interfere with a DVD player's electronics, why not with a CD player or an amplifer?

Jim

[WmAx]

Finding the answers to some of these questions would require careful experimentation and possibly modeling

WIth issues such as this, I tend to follow a logical methodology for consideration: IN this case, like many others: a claim is made, no substantiation is has been produced to confirm the claim/suspicion. I just can't take it seriously, especially with claims that have been around a while with no substantiation. If tht substatiation appears; I'll glady review it and accept if valid. I can not possibly assume or test/analyse for every possibility, since this would open up one huge can of worms you can't possibly count.

Try using a good A/C filter on your television while watching a DVD. If your power is clean you may not notice a difference. But if the power isn't clean ... If A/C nasties can interfere with a DVD player's electronics, why not with a CD player or an amplifer?

1st, I'm not comfortable discussing video implications. I have not researched, nor am I interested in video. However, since video and digital video devices operate at much higher frequencies then most audio equipment(SACD obviously being an exception), then it would seem to be rational that they would be more sensitive to high frequency interference from RF, etc as opposed to audio equipment that usually operates a much lower frequencies. Again, I have no knowledge of specific implicatinos on video.

-Chris

This post has been edited by WmAx: Aug 3 2004, 20:01

[Pio2001]

WIth issues such as this, I tend to follow a logical methodology for consideration: IN this case, like many others: a claim is made, no substantiation is has been produced to confirm the claim/suspicion. I just can't take it seriously, especially with claims that have been around a while with no substantiation. If tht substatiation appears; I'll glady review it and accept if valid. I can not possibly assume or test/analyse for every possibility, since this would open up one huge can of worms you can't possibly count.

I recall that this is not only WmAx' point of view. This is the very foundation of this discussion board. Claims about sound quality are not taken into account unless proven (see the Terms of Service, article 8, for explanations).

[jaustin]

I recall that this is not only WmAx' point of view. This is the very foundation of this discussion board. Claims about sound quality are not taken into account unless proven (see the Terms of Service, article 8, for explanations).

Not sure if this is directed at me, but for the record, I've made no such claims.

Jim

[Pio2001]

I believe that's where most available consumer electronics lie--in the middle, with adequate but imperfect power supplies, and adequate but not impervious circuit layout.  Why should we assume that they're either perfect or defective? Where's your evidence? 

If it is defective, it must be proven. If it is perfect, it can't be proven. That's why we look for proofs of defective devices.
So far we don't have any proof, with listening tests, nor distortion measurments, that power cables can change the sound of a device. And, following the theory, it is unlikely that they can. We have such proof for speaker cables under special conditions, but nothing yet for modulation cables, power supply orientation, digital cables and a lot of other doubtful audiophile tricks.
That's why we apply the skeptical approach : first find a fact, then explain it. Trying to explain a fact before proving its existence is, in average, a loss of time, because sometimes the fact is true, and sometimes it is false.

Not sure if this is directed at me

No, I just found that WmAx could have formulated it in a more definitive way, instead of presenting it just like his own casual point of view.

[jaustin]

If it is defective, it must be proven. If it is perfect, it can't be proven. That's why we look for proofs of defective devices.

With respect--and I mean that--both for you and for the rigorous standards applied on this board, I'm really not sure this makes sense. "Defective" is an intellectual construction. By extension, so is "perfection." If it is the absence of perfection, then (not meaning to get religious here) everything is defective, by definition. No proof is necessary: Everything is defective, to a greater or lesser extent. The key question is, can you reliably distinguish a difference, whether of character or of absolute quality? But I digress. Your definition of "defective" is inherently subjective: it depends on your hearing and jugement. Doesn't it make more sense, then, merely to speak of differences in quality, or even in character, rather than to embrace this perfect/defective binary?

A second question, of great significance to this board, but of far less fundamental significance, is: can you prove that you can hear it? Because to know something, and to be able to prove it, are quite different, as I think we all know from our everyday, nonscientific, nonaudio existence. Perhaps we COULD prove them, but we know them no less well in the abence of proof.

Jim

[Pio2001]

Your definition of "defective" is inherently subjective: it depends on your hearing and jugement.

Yes. For some people, Musepack -q5 is transparent. For other people (well, to make it short, for Guruboolez and Xerophase), it is not.

Doesn't it make more sense, then, merely to speak of differences in quality, or even in character, rather than to embrace this perfect/defective binary?

This is the next step. For example, discussing a problem sample with MP3, first, the ABX test is run. If it is successful, it shows that the difference is audible. Then, we can discuss what difference : noise, drop out, ringing, annoying or not, where in the file...

can you prove that you can hear it? Because to know something, and to be able to prove it, are quite different, as I think we all know from our everyday, nonscientific, nonaudio existence. 

We try to help people to prove it. It is sometimes difficult, but it is very interesting.

Perhaps we COULD prove them, but we know them no less well in the abence of proof.

I disagree. Many things that I knew without proof turned out to be false. Just a product of my imagination. I thought that I knew them, but I was wrong. Some other things that I knew were true.
It is always possible to prove something that we know and that is true, if we spend enough time and effort in the process. Sometimes the proof is not worth the effort. I think that it is what you call "something we know but can't prove".