The great power cable debate

48Sadly, a significant part of the home entertainment industry sells stuff for which bold quality claims are made, but which do absolutely nothing, at horribly high prices. Consider, writes Stephen Dawson, ‘audiophile’ power cables.

Four years ago, I saw an advertisement on the web for a used 10m power cable, called the ‘Coconut-Audio Rattlesnake Grim Reaper’. Cost $US80,000. Yes, you read right: the cost of a luxury car.

That’s, I guess, rather extreme. More, ahem, reasonably, there’s a site right now selling ‘award winning’ hand-made power cables, fitted for Australia, for prices between $US250 and a bit short of $US1,000. Elsewhere, there are plenty of power cables in the thousands of dollars.

Let me avoid any misunderstanding here: every single one of them is a complete and utter waste of money if you wish to improve the sound of the system. They not only do no good at all for the quality of sound in your system, they are completely unable to do any good at all. People claim to be able to hear improvements and they are completely fooling themselves. If a proper blinded test were conducted, they would not be able to tell any difference in sound between a system using one of those cables and the same system using a $10 cable picked up from a computer shop.

But it’s all about the sound!

So what claims are made for expensive cables? One very big audiophile cable maker has 10 models of power cables on its website. I was unable to find an actual online price, but they are far from cheap. On its website it says:

“No matter how perfect an AC power source, distortion is added within any AC cable, especially within a stranded cable. Even the most sophisticated filters and power supplies cannot eliminate this cable-induced distortion.”

The amount of distortion, whether you’re talking about some form of harmonic distortion or some kind of noise, added by a few metres of power cable is immeasurably tiny. Even if you generated a pure 50Hz or 60Hz supply with which to test the cable, you’re unlikely to be able to measure it, so low is the level.

Furthermore, you aren’t even listening to it! There is merely the power for the device. And to the extent that it exists, it is indeed eliminated by the power supply. Indeed, the power supply has to deal with much, much worse.

Let us consider what mains power actually is and we’ll see that the idea that a bit of wire might add significant distortion to it is utterly ridiculous.

Your wall outlet does not deliver a pure sine wave. Mine (and yours will be similar) delivers power from a cable that connects my office to the house’s switchbox, from where it runs through a circuit breaker, which in turn is fed (via a supply fuse) from a wire hanging in the air to a power pole, which is in turn bolted to an exposed cable made of anything other than oxygen free copper.

And this cable is attached to thousands of electrical devices in other houses.

Let’s stop there for a second. The outlet in my house is directly connected, with only the impedance of the cabling along the way providing any isolation, to the fridges of my neighbours as they switch on and off, their TVs and the switch-mode power supplies of their computers and phone chargers, and who knows what else. They are shifting phase and pushing little spikes into the mains, and dropping and increasing the effective impedance of the line.

And we’re worrying about the ‘distortion’ that a passive, inoffensive bit of power cable might add on top of this? Seriously?

But there’s more! After a few kilometres the local power supply runs into an 11,000V to 240V stepdown transformer (which, incidentally, is wired in delta configuration on the high tension side and star configuration on the 240V side).

That 11,000V line runs, after a few more kilometres of exposed wires, to a largish electrical distribution plant, where it is fed from another transformer which steps the supply down from 330,000V. That is fed, in turn, by more than a hundred kilometres of cables hanging from large metal pylons to a hydroelectric dam which provides the bulk of the power. But at various points the grid to which all this is attached and with which it is synchronised is attached to other power sources: coal fired generators, gas fired generators and an increasing number of windmill and solar farms out there somewhere, the various sources switching in and out, ramping up and down as needed.

And that’s only the ‘active’ cable. The ‘neutral’ cable is directly shared with three times as many homes as the active cable because by using three-phase power, all the ‘neutral’ signals tend to more-or-less cancel out. Approximately.

Somehow our ‘sophisticated power supplies and filters’ manage to cope with all this crap feeding into the power line, yet some claim that reducing the immeasurably small amount of distortion that may or may not be created by a metre of cable between the wall socket and an amplifier will make some kind of audible difference. Yeah, sure.

But I can hear the difference!

The same place that was selling the $80,000 power cables was also selling rocks. You put these special rocks on your hi-fi equipment and they make them sound better. Just rest them there. If the $US199 rock (‘designed to liquify your music to give a smooth and addicting listening experience’) does not sate you quite enough, you can upgrade to the $US299 model or, even better, the $US1,295 model. That special rock (hey, they do have ‘silver cloth’ glued to them) offers ‘quicker and tighter sound … more microdetail and higher resolution … bigger bass with more texture’ and on and on.

That’s the same kind of language one encounters when reading reviews of expensive power cables written by true believers. Impossible-to-verify subjective listening impressions. You can find them all over for all kinds of ludicrous ‘tweaks’ which can have no effect. Such as the adherent of Beltism who swears that the sound of MP3 files can be improved by putting a series of 1s and 0s into the ‘Lyrics’ (no, no, not the ‘Comments’!) ID3 tag.

Beltism is a set of very peculiar tweaks for audio systems developed – invented, perhaps? Or pulled out of his you-know-where? – by a British guy called Peter Belt. This particular weirdness has been around since at least the 1980s. It involves doing things like freezing your CDs and defrosting them to improve the sound, putting a piece of paper under one leg of your couch to improve the system, putting pieces of tin foil in certain books in your listening room to improve the sound.


In the May 1989 edition of Hi-Fi Answers there was a little booklet called: A Decade of Tuning Tips (Part Two). I’d love to see Part One, but I didn’t happen to purchase that edition. This booklet was by the highly respected hi-fi author and reviewer Jimmy Hughes, and the booklet offered an opportunity for him to proselytise for Beltism. As he writes: “I have experienced every one of these techniques in practice, and can vouch for the effects produced.”

And not only does he hear the improvements in the sound, so do unfortunate visitors:

“[P]ut a small piece of plain paper or card (that is, a piece with no writing or printing on it) under one of the feet of any piece of equipment with an even number of support points. You can use this technique very successfully on audio and video equipment, as well as on larger objects like refrigerators. I achieved marvellous results by putting a piece of plain white card under one foot of my sofa and chairs – visitors have often been amazed when I’ve demonstrated the effect on the sound produced by removing the card from under my sofa, and they could not see what I was doing.”

Imagine those poor visitors. Mr Hughes has some friends or acquaintances or relatives in his living room. He does something out of their sight and enthusiastically proclaims that — surely — they can sense the muddiness and sheer lack of tunefulness that his music system now produces, compared to moments before. In the face of his certainty, and his child-like delight, who but a churlish individual such as me could disagree?

I, myself, have managed to imagine differences in sound quality caused by things like changing cables and so on, but being such a churlish individual, I tend to double check. And when I start switching between the states I thought were different, I find that it was all in my imagination.

Thinking that you hear a difference in the sound of your system when powered via cable A versus cable B falls into a similar category. I, for one, having paid a couple of hundred dollars for a power cable to replace a $10 one, would be highly motivated to hear a difference.

Even if it wasn’t there.

Which it isn’t.

There are thousands of people who have convinced themselves that a non-existent effect is there simply through a little subjective listening. Which is why science invented A/B and double-blind tests.


I apologise. You come to Connected to read good sense about the best systems available for the home and find me discussing weirdly mystical claims about power cables. But as we’ve seen, there are weirdly mystical claims about a whole lot of stuff. Claims that are expressed with utter conviction, and often with the authority of some position within the hi-fi reviewing fraternity.

But I think it’s worth it to look at these things. And agree, it’s a good idea to stick with science and good engineering practice, rather than indulge impressionistic claims.

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