Saturday, 1 February 2020

MEASUREMENTS: Do power cables make a difference with audio amplifiers?


Alright guys, as you probably know, here at the Musings, I'm not in general a "cable believer". This doesn't mean I'm a "cable denier", after all, I need them in order to hear something from the system :-). Over the years I have written about silly cable claims, and here's the summary post looking at all the cable varieties I've measured (I will of course include this article in there as well).

With measurements dating back to 2013, I have neither heard nor seen any evidence to compel me to recant my opinions on this matter. Furthermore, I have not seen any new articles exploring the topic with any kind of depth in the audiophile press. No audio cable company has produced material demonstrating a believable, sonic benefits for their $$$$ products. Despite countless ads in magazines, I see a lack of accountability from the mainstream press to investigate; it's really just about maintaining the status quo and promoting sales of high-margin luxury products as far as I can tell. No magazine wants to purposely publish stuff that results in loss of advertising revenue from a whole segment of products, right?

Up to now, the power cable measurements I've published have been with low-power devices (ie. measuring DAC output quality with different power cables), but what happens with higher current demands, when the device needs >100W from the wall socket? In the last few months, since I've been working on amplifier measurements, I have had the opportunity to try measuring power amplifier output using different power cables.

As you can see in the image above, I have what can be constituted as an "audiophile power cable" on the right - a nice looking, thick, "HiFi Audiophile Power Cord" with advertised 4N oxygen-free copper (99.997%, OFC), 10AWG conductors, of typical 6.5'/2.0m length. The connectors are rather robust Hubbell HBL8215C, "hospital grade" plugs.

Here's a better look at the cable - rather pretty, I think, in a manly kind of way that might impress friends and family:


In contrast, behold on the left "The Nastiest Audio Power Cable In The World". I found this yellow 50' extension cable in the garage as I was getting ready to put up some Christmas lights in December. The 3-prong male end is tarnished after being outside over the years. On the other end, I used the thinnest IEC cable I have - a standard, generic 18AWG, 2m wire I got from an old AV receiver.

Yuck... Tarnished, dirty 50' garden extension cable in the garage.
I ran this test as I was wrapping up my Emotiva XPA-1L measurements because this Class AB monoblock is the most power-hungry of my amps here at home. When idle, this amplifier sucks up 100W of power based on my Kill-A-Watt meter and when asked to play a 100W sine wave into 4Ω, this amplifier will easily approach 250W power consumption! Surely, if power cables make a clearly audible difference, these two wires should be literally worlds apart in terms of quality and should also easily show differences.

Here's what the "test bench" looked like with the "Nasty Cable" plugged into the Emotiva amplifier:


Notice that this testing took place in my basement right beside that fridge. I temporarily unplugged the fridge during this testing to remove a potential variable.

As you can see to the right, my Autoranger and RME ADI-2 Pro FS are being powered off lithium batteries to keep noise low on the measurement side.

Before posting test results, consider these questions. What do you think I'll find in terms of differences when I ask the amplifier to reproduce test signals at various power levels? Do you think there will be extra noise detected from the amplifier output between the "Nasty" 50+' and "Audiophile" 6' power cables? Should there be distortions like more harmonics or intermodulation tones? Would using the "Nasty" cable reduced power output? All quite reasonable possibilities to wonder and ask about.

Let's answer some questions one by one...

1. I have heard some people claim that cables will change frequency response... For example, an "audiophile" cable can make bass notes even better, typically "more powerful". The high end might sound "sweeter" and "more extended".



Well, as you can see, at a typical 1W output which is not an unusual, normal playback level for home systems, there's no difference between the two cables. Notice how precise the overlay is out to 40kHz! at 1.002kHz where I put the cursor, it looks like the Audiophile Cable must be below 72.75dB and got rounded down to 72.7dB whereas the Nasty cable rounded up to 72.8dB.

2. The Nasty Cable, being >50-feet must result in higher resistance and impede the amount of current to the amplifier. This would reduce the amplifier output when all else is the same.



Well this one seems to have some objective support. Remember that I'm measuring output voltage across the 4Ω load through the Autoranger so the dB scale on the left is relative to how much attenuation the device applied; what's important is to look at the difference between the two cables with the Autoranger applying exactly the same attenuation.

Indeed, we see that the amp output with the Audiophile Cable is visibly higher. That's an interesting finding, but remember, we're still looking at just 0.1dB-level difference at 1kHz! So, despite the amplifier drawing >200W from the wall socket, I'm simply not impressed that this small change could result in the type of audible differences some people claim can be heard with power cables.

3. I believe that I hear a difference in distortion - an Audiophile Cable "of course" results in lower noise and distortion, right?


Click on the image above to examine closer. See any difference at a typical 1W output level with amount of harmonic distortion across the spectrum? I don't.

Fine, how about looking at the FFT at 1W and also pushing this to 100W:


The graphs above are the FFTs at 1kHz with the amplifier playing at 1W and 100W into 4Ω using either the Audiophile or Nasty cable. First, notice that there was no difference in the amount of 60Hz hum. Even with a 50+' cable, it's not picking up anything unusual (I have some compact florescent pot lights in the room turned on). In fact, even if I plugged in the fridge, nothing changed (not shown). This amplifier appears quite resilient to electrical hum.

If anything, with the Audiophile Cable and the amp playing the 100W signal, there's some very low level "needles" around the 2nd harmonic not seen with the Nasty Cable!

If you look at the dBFS levels on the top right of each FFT, we see that the Nasty Cable has a slightly lower output level - this is consistent with the 100W frequency response graph in section (2). Now if we drill down to the highlighted THD+N results on the top left, we see that indeed, the Nasty Cable achieves slightly worse distortion numbers. Notice though that the THD+N amount is only something like 0.2dB difference between the two cables! While there is some inter-test variability, when I captured a few of these results, there is a general tendency towards mildly superior THD+N with the Audiophile Cable.

0.2dB difference in THD+N? That's all, folks...

4. But Archimago... It's all in the transients!

Okay. Let's see then if out TIM test tone that especially looks for distortion at the edges of square waves with >90kHz bandwidth (signal samplerate at 192kHz) shows a difference:


Nope... Nothing all that exciting. Remember what this test represents. It is asking the amplifier to continuously reproduce a 1kHz square wave where the edges are transitioning suddenly from about +6V to -6V (and vice versa) - >12V transients, 2000 time/s - into my 4Ω resistor while having a 12kHz sine wave overlapping. If this is reproduced poorly, we'll see noise and "sidebands" develop. While there are some sidebands with this amplifier on either side of 12kHz, notice that they are low (below -90dB from the 1kHz peak), and it made no difference whether I'm using the Nasty or Audiophile cable. 

5. Fine. I bet you'll see an abnormality with the more complex multitone and intermodulation tests!

Let's go straight into the triple-tone signal and look at total distortion & noise:


With 3 tones, there are ample opportunities for us to look for intermodulation sidebands as well as other distortions (including Class AB crossover distortion components) and of course worsening of the noise floor. Again, I'm measuring this at 6.32V into 4Ω, approximately 10W continuously which is louder than one typically would be asking the amplifier to output when listening at normal music playback levels at home.

Notice that I am able to show slightly worse TD+N with the Nasty Cable. What is key is the magnitude difference - again, only a 0.2dB difference. This is consistent with the worsening in THD+N above. I did this test switching back and forth three times using the two cables and can say that I found this difference to be real and replicable.

Conclusions...

It's good to see that my measurement system was sensitive enough to show a very slight (~0.1dB) amplitude reduction when the amplifier was pushed to 100W playback with the Nasty Cable. Likewise, there is a 0.2dB worsening of THD+N and TD+N when I used the poor cable. This gives us a good idea of the magnitude of differences one might find between power cables even though this test used an extremely poor outdoor garden cable for comparison :-).

As you can see, I didn't spend much money on that "HiFi Audiophile Power Cord" - ~US$20 ;-). Whether I used this 6' cable with claimed 10AWG 4N OFC conductors or an atrocious 50' utility garden extension cable with tarnished connectors plus 6' 18AWG IEC cable to the amplifier, it simply does not make a difference to any significant degree.

Some audiophile friends I'm sure will be impressed by the girth of the Audiophile Cable and how good it looks connected to my Hypex NC252MP amplifier these days. Nothing wrong with having nice looking window dressing (one of the "non-utilitarian benefits" we can spend money on)! However, there are probably a few thousand other things I'd put higher up on the list of purchases before I'd spend >$100 (never mind $1000+) on a single power cable in the belief that it affects "sound quality".

Over the years, audiophiles have been exposed to many articles and discussion threads about this topic. Just recently, I saw this thread on the Steve Hoffman Forum, and in there, we have a link to this Q&A "Why Power Cables Make a Difference" by Caelin Gabriel of Shunyata Research. Notice how we've always been treated to words. Words that allege significant differences or tries to make the topic complicated by dragging up variables like inductance, capacitance, impedance, EMI, etc. without useful context to the point where the reader is either numbed to death or falls prey to fear, uncertainty, and doubt thinking that this guy is right and there's some magical, remarkable quality to these cables that will enhance sound magnificently!

If a cable company (come on Shunyata, AudioQuest, Synergistic, Kimber, Furutech, Crystal Cable, Audience, and others) seriously wants to promote honest discussion, just show us some results from DACs or amplifiers that demonstrate the differences they speak of using their cables. Show us the magnitude and under which conditions they find a difference whether due to special cable geometries, OCC copper, silver conductors, monocrystals/filaments, specialty connectors, tuning "bullets", fancy dielectrics, super shielding, etc. Likewise, companies that sell expensive power conditioners claiming audible improvements - consider this breathless sales pitch video with drama and back story, check out ~10:00-14:00 for manufacturer claims - need to consider the same.

Remember what Carl Sagan said about "extraordinary claims..." The claims being made about power cables have poor face validity even without objective data. Unless there is evidence beyond testimony, we're truly just wasting our breaths and keystrokes incessantly discussing or disputing claims. Keystrokes are cheap and anyone can claim that they heard anything online. Most of the time, at best, I believe folks are just expressing a subjective opinion in good faith, at worst I wouldn't be surprised if there are occasions where testimonies have been written falsely to advertise products.

I think most reasonable audiophiles at this time in history recognize that the "high end audio cable" industry is really nothing more than about selling "impressive" looking luxury products (plenty of inexpensive good looking ones out there these days). On the odd occasion, perhaps a more expensive cable might be less susceptible to noise and if one is using extremely thin cables, a thicker one might reduce a bottleneck with power-hungry devices. I believe audiophiles and music lovers should just be reasonable and follow straight forward electrical principles (here's a 10' 14AWG Monoprice for example, or a 6' 14AWG Pangea Audio for a few bucks more), turn up the BS detector when you see the ads of 4-figure power cables claiming apparent sonic improvements.

As I've also said before, remember that there's nothing wrong with buying expensive products if it looks good to you; just be clear about what you're buying it for and be able to show humor regarding one's neurotic beliefs if this be the case.

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Okay guys and gals, remember, get me your impressions for the "Can you hear high harmonic distortion?" blind test started last week!

I had a quick peek at a handful of submissions and can say that at least 1 person got the order from least to most amount of distortion correct :-). It's clearly doable and like I said before, should be much easier to hear a difference than a "hi-res" vs. "standard res" listening test!

Despite all that's going on in the world, I wish you all a good February, and still enjoying the music.

73 comments:

  1. Nice test. The outcome doesn't surprise me. Although I expect 'believers' will tell you the test is flawed because your 20$ Amazon cable can't be taken seriously. You need to shell out at least 400$ to witness magic.

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    1. $400? How about $1845 per meter? https://positive-feedback.com/reviews/hardware-reviews/rsx-technologies-beyond-power-cord/

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    2. And according to the review the difference should be easy to measure: "The overall and most consistent nature of Beyond is an improved dynamic range. It extends the high band, enhancing sparkle and air. The mid-band is a bit more powerful and beautifully".

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    3. Hey Geert and Joe,
      Them's beauteeful power cables, alright. And Bob Levi is a lucky guy to have heard the songs of cherubim ;-). I find it funny how he advocates "one should have a strong selection of excellent power cords handy to max out your key components". Wow, so one expensive cable is clearly not enough! Dang, I also forgot to mention brands like Cardas and Kubala-Sosna on my list of questionable companies above.

      Indeed for the "believer", a 6' $20 cable isn't going to get them excited. But then again, compared to a 50' garden cable, I still think this says something about what "potential" power cables truly hold. I trust that the "silent majority" of what I believe are reasonable audiophiles and music lovers get the point...

      Suppose we did want to indulge in satisfying the "believers". Is $400 enough? Why not $1000? How about $5000? It never ends, does it? Such is what happens when we chase after luxury and fashion. The more we do that, the further we get from the actual utilitarian value of simply "high fidelity" transmission of electrical signals.

      I would have borrowed some Synergistic power cables like I did a number of years back:
      http://archimago.blogspot.com/2014/02/measurements-power-cable-redux.html

      But for some reason, in the last 5 years, all my audiophile friends put their stuff up on Audiogon and got most of their "investment" back :-). BTW, the $20 cable doesn't feel that different from the Synergistic years ago and I think the blue color looks better!

      I think no matter what is said, published, tested, the "true believers" will only listen to one thing... The voice of their prophet whether it be Ted Denney, perhaps Caelin Gabriel, Garth Powell, or maybe folks like Bob Levi and the various audio savants at Hi-Fi+, TAS, 6moons, Part-Time Audiophile, etc. with their cable reviews.

      Sadly, those entities never publish data, do not engage in facts around the electrical properties of these products, and can only interact through testimonies based on faith in their "experience" and perceptual abilities. It's alright... Autonomy is good. Believe. Buy. If one is inclined.

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    4. Oops, forgot to log in for the comment above...

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    5. And it's easy to measure an increase in current, but I'm not sure how one could measure the "black background" enhanced by the double insulation. "The hefty copper composition seems to let more current into the amplifier, while the double insulation enhances the black background".

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    6. Need a "shoulder shrugging" emoticon :-).

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  2. Betteridge’s Law requires one needn’t read the article. :-)

    Although the correct (albeit pedantic) answer to that headline is, "Yes, indeed. A power cable is required in order for an audio amplifier to function as designed; a lack thereof tends to catastrophically limit performance."

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    1. Hey Gnu,
      Always the wise guy eh? :-)

      However, in this case, beyond the pedantic response, we can still answer with "yes"! It does "make a difference" but down at the order of 0.1-0.2dB for amplitude (when pushed to 100W output) and distortion (down into the depths of -80dB).

      Of course, not a particularly satisfying answer for those who are looking for a clearly affirmative answer to hearing big differences. (And I suppose a disappointing truth that audiophile power cable manufacturers must already be aware of even if not publicly expressed.)

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  3. As someone who has been involved in DIY audio electronics design for a couple of decades, I have always found it extremely amusing that people buy into the power cable argument. Considering that the same type of Romex electrical wire is supplying the power across a far greater length than the wall to amplifier cable, and that the single greatest source of power related noise lies in the rectifier bridges that live inside the amplifier power supply itself, the contribution of cable related noise is infinitesimal compared to these other influences. I'm brought back to a demonstration I attended once where a cable manufacturer made claims that cold welded (i.e. crimped) connections were far superior to soldered connections. Somehow they ignored influence of the several hundred soldered connections existing inside the various audio electronics, somehow unaware that they were really comparing approx. 500 vs. 501 soldered connections in the audio signal path and figuring that this somehow mattered.

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    1. Hi TJAB,
      Yeah, I agree. The argument is important yet I see many audiophile cable advocates insist that "the last 6 feet is the most important" or some similar argument.

      As usual, folks can say whatever they want but I have never seen any evidence for such claims...

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  4. Hi Arch
    Not criticizing your methodology, but wondering if you reran the tests and got consistent results.
    My first thought about the .1dB difference was: maybe power line fluctuations?
    Just a thought
    Phil

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    1. Hi Phil,
      Yup, I did rerun the sweep test a couple times and from what I can tell, the garden cable did restrict amplitude by ~0.1dB from this amplifier when playing the 100W signal...

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  5. What about voltage drop in the cable? 10 Guage 6' looses about 1V and 18 Guage 50' looses 10x the voltage!

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    1. AC vs DC friend. 120V 50 feet 18 awg cable would drop like 0.5V

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    2. Yup. I didn't specifically test the voltage drop but I'd expect something like that...

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  6. When testing my Crown amps on the bench, even my very nice 14ga cable, only about 3 feet long, drops 10V when pushing the amp to clipping. It's enough to prevent the amp from meeting its power specs despite the good regulation in the amp power supply. It doesn't seem to affect noise measurements though. I really need to run something like 8ga from the box to the bench for high power testing and find a bigger power cord, just to be fair to the DUT.

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    1. Wow greg,
      How many watts again is that to clipping on that Crown!

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  7. Of course he didn't test power cables that have, longer more secure prongs that have less contact resistance with the wall , real high quality materials or complex geometry , quadruple or more shielding ,are really low guage to allow for more instaneous current , or with actual noise filters built into the cable that filter noise from all that romex wire and power lines that proceed the power cord.. he tested a $20 power cord from Amazon and there was still a small differences which is all you should expect for only spending $20....... there are many people with ears that could detect .2 decibels difference that are reported in this report even in the 20 dollar power cord he found was slightly better than the extension cord...lol... it's a scientific fact of human hearing ..... this obtuse author should look at the measurements of shunyata power cords compared to regular stock chords and all the patents they have...documented all over the place

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    1. Lol, yeah, ok, you go and spend your money and believe the nonsense. I for one prefer to believe in Physics.

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    2. Hmmm… obtuse. Before calling the author obtuse you might want to check out the links he included in this post on earlier measurements he has done.
      Expensive power cables used as a filter? Most well designed audio equipment and their power supplies with additional circuitry for filtering out noise are quite capable of doing this on their own. And you can expect that the higher end equipment is the best at doing this, which makes buying expensive power cables as filters even less important.
      And as far as a .2dB change being audible, a quick google search might prove to be enlightening.
      Shunyata measurements? I would need to see some independent test data, not something from a manufacturer’s website.

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    3. The author should have tested power cables that were equal length....the longer,cheap extension cord because of the extra length would be more inductive which helps suppress high frequency noise...bahaahaaa..i cant breath ...and yet it most measurements ....the shorter 20 dollar cord still measured slightly better
      .....and would have measured better in that specific noise test with sidebands if the length was shorter on the extension cord and equal to the audiophile cord

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    4. Better still was the fact he used an emotiva product....its a very good product for the money...but emotiva amps have been measured in stereophile with state of the art audio precision measuring equipment and the emotiva specs dont compare to the state of art specs of higher priced audiophile amps.... so of course ..the emotiva s poor specs in many regards would somewhat mask the differences between the power cords....even with the flaws in this experiment of not using equal length cords....and using an amp that does not measure well compared to other audiophile equipment ... ......the 2o dollar cheap by audiophile standards cord still measured better in almost every aspect....lol

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    5. Well there you have it. Sorry Arch, but Miketruth has convinced me with his succinct, scientific, rebuttal to your test and my points. Clearly power cables really do make a difference. Maybe you should leave the power cable reviewing to the professionals at the audiophile publications until you get some more "resolving" gear.

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    6. Love it Miketruth :-)

      Look...
      1. Sure. By all means buy "longer more secure prongs". Enjoy the fancy geometry. Spend money on quad shielding (!). Could you point me to an example where a company has demonstrated that these things actually improved performance of any amplifier or DAC though before the consumer drops the cash?

      2. "there are many people with ears that could detect .2 decibels difference". You do realize that I'm talking about 0.2dB difference for measurement of THD+N or triple-tone TD+N with the amplifier capable of reaching down to -80dB, right? So you're saying that you or someone you know can tell the difference between amps with -80.0 vs. -80.2 THD+N level of performance? Better take that THD blind test and check for yourself then we can talk about this again!

      3. Longer power cable suppresses high frequency noise. Hmmm... So you might perhaps purposely use longer power cables because they're less noisy? Can't say I've heard of that one as a general audiophile recommendation. Take a breath; no need to have a panic attack!

      4. Actually, for a Class AB amp, the Emotiva XPA-1L IMO is good. Much better than some esoteric designs that cost much more. Seriously, if power cables made a huge difference as some contend, shouldn't we see a bit more difference here? Have you ever seen a measurement using "state of the art" equipment that ever showed a big difference between power cables?

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  8. I don't know, man. I know that any measurements are going to proof that it doesn't make a single difference. But I've heard the difference before at a friend's setup. It was repeatable, with observable differences (not necessary always an improvement). Well, it did nothing in my setup, so I don't bother much with expensive power cables.

    You can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time. What boggles me is this: why is it that audio cable industry simply refuses to die when measurements says their cables make no difference? Usually, if products do not do what they claimed, the companies or the industry would die off eventually, placebo or not. "Cable manufacturers' marketing" & placebo might have an impact, but to me they do not sufficiently explain why so many people hear the difference (and buy them). This industry has only gotten bigger, with more new companies.

    But let's ask ourselves this: if it is observable to a person (and the person can afford it), does it matter if others don't hear it and measurements says otherwise?
    Just like placebo in medicine... if a person gets well due to placebo effect, is it such a blasphemy for a person to keep doing it even if science/research/double-blind whatever says it doesn't work?

    I choose to think that there's got to be some scientific phenomena that we don't know about, and we are only able to observe the end result through human sense for now. We can't claim to have reached the end of understanding this universe. Until then, I'd buy audio gears that preferably come with proper measurements or scientific basis, and also has an observable improvements to my own ears.

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    1. Hi YW,
      The way I see it, the reason the cable industry doesn't "die" despite measurements and such is because this is all about psychology. It's social science rather than basic science like physics which show us objectively that there's really nothing "there".

      There are many things in our world where psychology wins. The placebo (and nocebo) effect is one where people will report objective "truth" in the efficacy of some treatment. Likewise, as human beings we spend all kinds of money on dubious products, have faith in things with unlikely effects (naturopathy? Gwyneth Paltrow Goop?), unusual theories (conspiracies? "flat earth"?) or the countless cults/superstitions/religions.

      If owning these products or having a belief in these things add quality to life (like the placebo effect), then so be it. Some are OK with this and I would not want to be overly paternalistic in forcing anyone to drop the beliefs. All I can do and say is that I have done more in articles like this than just "listen" as an audiophile because testimony is not enough for me. And I want to encourage audiophile to think for themselves, be OK with pointing out issues with the way these things are written about and advertised.

      As such, I would suggest that audiophiles kindly request (and have the right to ask) cable companies to explain the value of power cables that demand hundreds if not thousands of dollars!

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    2. Archimago,

      It seems to me there are a growing number who want to give voice to being a Rational Audiophile. Your web site and voice being one of them, and some of us are trying to give voice to this view in other audio forums/comment sections etc (as I see you do as well).

      By "rational" I mean of course thinking critically about ideas and claims made in this hobby by manufacturers and our audiophile friends. Not pretending our hobby is some subjective bubble sealed off from science, measurements, and what we know about the capacity for human delusion and mistaken inferences through various biases and perceptual errors.

      The purely subjective approach is no doubt seductive to many. It melds beautifully with the brain's natural inclination for motivated thinking, confirmation bias etc. And a lot of people see upending confidence in their own subjective inferences to be destabilizing. "You mean I can't TRUST my perceptions???"

      There's also the seductive benefits of keep a pleasing non-falsifiable
      belief. If I claim to hear the singing of fairies when I put a new cable in a system, so long as I eschew any method of disproving this claim - that is a test for how my subjective inference could be false - then I get to hold it as long as I want, as long as it's doing pleasing things for me.

      It can't be falsified, or have evidence against the claim, by having you listen for the fairies and point out you don't hear any. I can just claim that shows you don't have the same perceptual powers a I do. Poor you. Without any way to test my claim, I get to hold on to my status of "Golden Ears." And I'll continue to reject any rigorous/objective way to test my claim.

      And this epistemic move of subjectivity over any objectivity spills out ever wider. "The problem with measurements is that we often can't measure things we hear." Like what? "Oh, like the fairies I can hear singing when I use my new cable! (Or the golden hued tones or whatever)." Or the FACT that I can hear new dynamics when I use my new PS Audio power purifier, or the FACT that I hear a more organic believable tone with my Shunyata AC cables" and on and on. These of course are pure question-begging claims. But insofar as a pure subjectivist rejects the legitimacy of any rigorous attempt to vet what he thinks he is hearing - e.g. blind testing or through measurements - it becomes part of the enlarging subjectivist story for how "measurements can't be brought to bear on what we often hear."

      It's pretty rough trying to speak up for the side of questioning these subjectivist dogmas and giving reasons for a more skeptical approach. Many audiophile forums simply assume the subjectivist stance, even when many members are not fully in that boat, and view anyone giving voice to caution about many claims, with appeal to measurements and pointing towards human weaknesses to be accounted for, as simply party-bargers ruining it for everyone.

      An example it seems would be this thread from the Stevehoffman forums. I'd heard the forum has one of the most trigger-happy ban-hammers in the game, but I found out first-hand it's true. In a thread asking "Power Cables...do they really matter?" I gave an answer doing my best to present the case for being cautious:

      https://forums.stevehoffman.tv/threads/power-cables-do-they-really-matter.888777/page-2#post-22287503

      It got 17 likes, suggesting it spoke to or for numerous forum members, and it was praised for it's non-confrontational evenhanded tone.

      And yet that got me banned from the thread! Where the subjectivist case for "of course they do, because I can hear it" can be made with abandon in that thread. And the amazing thing is that those of us who point out our natural human fallibility and why it makes sense to take it in to consideration, and talk about how we can be shown to be wrong, are viewed as the dogmatists!







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    3. Well said Vaal,
      I do hope that over time, the voices of the more rational audiophiles grow into a chorus of educated enthusiasts that embrace and reward companies that innovate with meaningful technologies rather than one that stagnates or even worse regresses into idiosyncratic products and archaic technologies judged primarily on opinions of the few.

      Certainly as long as I have been interested (since the late 90's) in audio, the quackery and pseudoscience promoted among audiophiles have been painful to watch. Remarkable to me that so often, the magazines and reviewers seem to not be able to show what I would have thought would be even a basic level of reality-testing!

      It is fascinating watching how people write and think on the online forums. Certain personality styles show through. We can also see at work communication skills and ability for intellectual discourse variably expressed.

      Yes, likewise I have seen some of your comments on the forums. It's never easy giving the "minority report" depending on the culture and assumptions of certain forums but it is important in a free society - even if we are operating in our tiny corner of the Internet.

      Good luck and hope to run into your thoughts among the forums!

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  9. Also, thank you for doing these measurements. Hope to see manufacturers being held accountable for their claims, and keep an objective eye in the hobby.

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  10. You should read up on "placebo effect". It literally means an effect which is observed even though there is nothing in the "treatment" which could cause the outcome. It is related to the subject-expectancy effect. If it works, fine, but it is morally questionable for someone to recommend a placebo which has no measurable effect.

    People continue to buy tweak cables because they accept the hypothesis that there is really something there and would rather believe they hear something than actually perform an experiment which would prove that it's just psychological. The cable manufacturers depend on this self-deception.

    And let's not get into the fact that most of the connections leading up to the wall socket and following the power input connector are of far worse quality than these tweak cables. The power cable is not the choke point.

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    1. Agree Greg,
      Just to add, we should ask ourselves this about placebos...

      Is it ethical for a doctor to prescribe a medication he/she knows to be a placebo? Suppose it's a one-time medication and it costs $1000, plus the doctor pockets some of the proceeds from the sale. Is that OK even if the doctor says he's happy to refund the cost if the medication doesn't work but lets the patient believe in the power of the placebo if it does?

      Delete
    2. Doctors are ethically obligated to only prescribe placebo with patient consent.

      There was a study of hearing aid wearers where acoustically identical aids were supplied but one was called 'traditional' and one was 'new tech'.

      Patients did better on scoring.

      So my question is should hearing aid centers send out bulk communications so their customers can come in for an 'upgrade'.

      Delete
    3. Hey Matt,
      I don't know about the hearing aid situation. Wishing good hearing for everyone of course. ;-)

      In the Western world, there is the need for informed consent for such things to be considered ethical. When we buy regulated pharmaceuticals, we expect that companies and the government have done due diligence on safety and efficacy.

      I suppose one could argue that audiophile products are not formally regulated so it's OK to have a "wild west" where anything goes and ethical standards are expected to be relaxed. Even so, I would hope companies would follow basic principles of business ethics - including social responsibilities like honesty and fairness towards their customers. If we're not sure about whether these companies live up to decent standards, then all the more reason for hobbyists to perform measurements and discuss the value of products ourselves while being mindful of biases being introduced by the companies or mouthpieces.

      Delete
    4. I agree - mostly. But I think you're forgetting a couple of very interesting aspects to the placebo effect.

      The effect is shown in this article with wine price being the variable (https://phys.org/news/2017-08-expensive-wine.html). The interesting bit (for me at least) is that there WAS a measurably different response in the brain ... the people did really enjoy the wine that they were told was better more as measured by brain response.

      Given that any sensory input (sound, taste, vision, proprioception etc) is only processed in the brain I can well understand that some people, having been told that the 'magic cable' will perform better will genuinely enjoy it more and will be absolutely convinced that this effect is externally measurable rather than simply an artifact of imperfect human sensory perception.

      As a rationalist, I DON'T believe my senses ... I know how flawed they are ! What's measurable objectively is much more likely to be real.

      Delete
  11. Hmmm what about the cable between power socket and distribution board? Or back to the power station?
    I think my sound is more open and natural if I use a green energy supplier, but a coal fired power station is better for metal.

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    1. Ha Ha ! Yep, for "believers", 3 feet of high end cable is more determinant than the 30 feet of cheap 14-2 electrical wire that brings the power to the socket from the electrical panel !!

      I would not be surprised to see soon in audio magazine "audiophile breakers" to replace the regular 15A breakers and for sure, they will be said to improve the definition and the soundstage !!!

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    2. Not necessarily for audiophiles but maybe something like this?

      http://www.equitech.com/products/wall/wall.html

      I suspect that might help more than any $5000 power cable :-).

      Delete
  12. I think it is difficult to find difference between two round shaped power cables by measuring.

    In the past, I tested 10 meter VVF flat power cable runs adjacent and in parallel with 10 meter analog RCA cable and play/record test signal and found there was a measurable power induced noise recorded.
    And the noise was somewhat reduced with round shaped power cable or XLR balanced analog line cable (10 meter).

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    Replies
    1. Interesting... Can't say I've ever tried flat cables. Good thing I stuck with round cables and minimize parallel runs with interconnects ;-).

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  13. Great article Arch. Thanks. How about running the tests with RFI filtered socket in place. Something like tke MK K1826 HHI for the UK market.

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    Replies
    1. Interesting. Will see about this. Do the manufacturers publish any data as to the benefits and how much difference this makes? I suppose in many ways this is at least part of what power conditioners are doing?

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  14. HHI=WHI (it's just the colour) Sorry.

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  15. Since I use regenerated power via PS Audio and upgraded, tho' not exhorbitantly priced, power cords for all my components, I was wondering if the tests were rerun with power cords more expensive than $20+/- and more upscale amps, would there be more and/or greater measured differences. Comparison(s) could be made with the $20 cord as reference tho' from your measurement a garden cord could also be used. ;-)

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    1. Don't know Guy,
      Maybe others can give it a try themselves...

      Of course my fantasy is that a transparent audiophile cable industry would do these experiments and tell us!

      Delete
  16. Arch,
    Interesting results.

    Thought I must say the results probably only reflect your exact test case; I suspect you could use a super-conducting power cable and still not see any measured difference with the Emotiva Amp. No offense to Emotiva owners, my guess is it's the bottleneck in your test.

    I'm certainly not a subjectivist as such, but there's no mistaking the sonic impact of a good power cable on a good Amp. Listen blind for yourself.

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    1. "Listen blind for yourself."

      I have over the years. Including with Synergistic power cables, "hospital grade" cables, and really poor wiring like the 50' garden extension! Have even done this with other audiophiles including those who "believe". Never heard a difference and more often than not, the "believing" audiophile friend sells off his expensive cable(s) :-).

      Delete
  17. Great stuff Archimago! Great to see you doing this, and the results are hardly surprising.

    But..ooooh...how I wish you were able to use a more high-falutin' power cable. One of significant repute among the audiophile audience and press. If only because it's so predictable that most cable-believing audiophiles (including even some on the fence) will likely dismiss the test based on the essentially no-name cheap "audiophile" cable you tested.

    If I still had an audiophile AC cable from Shunyata or the other Usual Suspects, I'd be the first to send it to you!

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    1. Thanks Vaal,
      This is IMO more psychological than anything else. From my perspective, it doesn't matter what cable I test because ultimately those who want to believe will have other complaints like what amp was used, what DAC supplied the test signal, what measurement equipment recorded it... Must I use whatever is the "best" amp du jour touted by some audiophile magazine? Do I need AP test equipment to check if power cables make an "obviously" perceivable effect based on some people's testimony?

      The bottom line is that I have no reason to believe the power cable industry speaks truth. I have not personally heard it. I have not seen any evidence. If they are speaking truth, perhaps they can come forward and provide evidence themselves using whatever equipment they wish to educate the consumer.

      Delete
  18. If any of your commenters have a cable that they think would be clearly superior to the garden cable, perhaps they'd be willing to part with it for a few days and send it to you for testing. As for your Emotiva monoblocks not being expensive enough to expose the difference between cables, I suppose you might have to unplug your Hypex NCore amp to test that Shunyata Sigma power cable.

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    Replies
    1. Hi distler,
      Yeah, hey, if any listener wants to send me a cable to try (ideally locally since I'd hate to have mail lost with an expensive product inside!), get in touch and I'll see what I can do. The reason why I didn't use the Hypex is because the amp is so darn efficient with less than 50% power draw compared to the Emotiva!

      Delete
  19. as much as I love this site I think this test isn't your best one.. no matter what, you really should use proper audiophile cable for this test.

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    Replies
    1. Sure pam,
      Perhaps in time :-).

      Now which cable brand would you guys like me to keep an eye out for?

      Anyone want to put bets down if they think the results will be any different from the $20 cable?

      Remember, the point of these measurements and posts is NOT to single out any single cable or brand. I am personally NOT going to be putting any money down to purchase a cable if there is no evidence of benefit and I can buy an inexpensive one that looks great already because IMO, that's all they are - audio jewelry.

      Ultimately the companies are the ones who should be showing the consumer the evidence for their product if they want to claim "better sound". It's more important to think about the implications and meaning of what was demonstrated than get concerned about the "magic" of individual products...

      Delete
  20. Hello and thanks for a very interesting article, all the more so since the discussions have moved beyond the particulars of your test to its implications. First, let me say I found your power cable comparison and its implied argument that power cables don't make much of a difference very compelling. However, to admit my own confirmation bias, I believed that to be the case before. But then I guess I can't consider myself an audiophile, because I'm not primarily interested in making a hobby of audio equipment. I do, however, listen to recorded music a lot, much more than I watch TV, for example, and I have found that some playback equipment can make a big difference in how much I enjoy and am able to focus on the music I listen to. This goes back to 1977 when I replaced my first Pioneer 15 watts/channel integrated amp with an Advent receiver, also 15 watts/channel but with much clearer (less "veiled and congested"?) sound. With the Advent in my system I could readily discern, for example, the fourth voice in a Bach fugue on harpsichord I knew to be there but that was faded into the flattened micro-dynamics and instrumental textures with the Pioneer. I have no idea if there was a commonly measured aspect of those amps’ electrical outputs that would have accounted for the perceptual differences, but Henry Kloss, the designer of the Advent, did something differently from the people at Pioneer that produced the results I could hear. So, I believe in and am interested in the differences between equipment when and because they make differences in my ability to hear the recorded music. Yesterday, I listened to an interview with Paul McGowan of PS Audio. I understand that he is a trained electrical engineer, and continues working with design teams at PS Audio. The last time I heard one of his products it was very good, so I can’t doubt his knowledge and experience. Also, as far as I know, PS Audio doesn’t make or sell cable products. He made the point that many people, including he himself and other highly competent engineers and designers of audio electronics and speakers, have claimed for years to hear significant differences between different interconnect and speaker cables, so that professional audio engineers must take these differences into account when they are designing and testing equipment for their companies. There is, in short a persistent phenomenon, and the fact that currently used measurements do not describe the phenomenon is just an indication that engineers have not discovered every relevant measurement parameter.
    I bring this up not as a challenge but, first, because I am confused. Second, it’s important to me because I am in the market for several new pieces of equipment that will have to last me for a long time. The comparisons I made in 1977 are becoming increasingly difficult in the US as there are ever fewer brick & mortar audio dealers. (So I also want to thank you and emphasize the importance of trustworthy media reviews and discussions for us consumers.) And comparisons of cable products have always been logistically very difficult, even though the shops always pushed them, perhaps for obvious reasons.

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    Replies
    1. Hi Mike,
      Sorry did not respond earlier to this... As you can see, I must have responded to this PS Audio/McGowan interview recently ;-).

      To be honest, I cannot believe all that McGowan said as discussed in those posts. It's one thing to argue about the potential differences that an analogue cable can make, but a very different argument when it comes to USB and cables that carry digital data.

      I believe McGowan will need to do better if he truly wants to be convincing. Just because he works in the audio industry for years in itself is not good enough when it comes to improbable claims IMO.

      Delete
  21. I wonder if any manufacturer of high-end cables would be willing to submit a cable for this testing. If a significant measurable difference was established between their cable and the 20 dollar cable then this could be used to validate the high cost of their cables any would surely be a great boost to their sales. If, on the other hand, no significant measurable difference was established they could go back to the opinion that the scientific tests are not advanced enough to account for the fine subtleties in human hearing. What do they have to lose?

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  22. Is anyone aware of any court cases concerning the claims made for high-end power cables? Here in the UK we have the Advertising Standards Authority that regulates claims made in advertising. I thought you might be interested in a ruling by the ASA regarding claims made by Russ Andrews who are one of the most well known sellers of cables over here; https://www.theregister.co.uk/2011/01/13/russ_accessories/
    It might be amusing to compare the advertised benefits for the same cable before and after the ruling

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    Replies
    1. Fascinating information! Thanks for that link from 2011.

      Certainly here in Canada, all provinces have consumer protection agencies to hear customer complaints. Whether a "hi-fi cable" has ever been tested based on legislation I have no idea...

      But hey, nice to have the precedent set in the UK!

      Delete
  23. Not sure where you guys read that Paul McGowan is an electrical engineer. From his LinkedIn bio, he graduated from high-school and by his own admission self taught himself everything he knows.

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    1. Interesting. Hopefully Darko will ask him in the next interview ;-).

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  24. Hello. Good test, as usually.
    I would like to believe that people with at least basic education in electrical engineering do not buy those uselesly expensive cables :-)

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    1. Right.. EE education or not, I hope everyone can just activate a few neural circuits to examine their own cost-benefit equation before handing over that credit card number :-).

      Delete
  25. Perhaps I misunderstand, but it seems to me that what you're testing is the quality of the power feed coming out of your wall socket, which will vary wildly from one location & power utility to another. The more interesting test would be one of the run between a good power conditioner (I'm using a Bryston BIT-15) and the preamp, amplifier, or whatever. That's a context in which I believe a decent gauge shielded ofc cable can make a difference because I've heard it.

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    1. Hmmm, Will, if I did that, shouldn't a ~$3000 line conditioner like that make power cable differences even less significant?!

      Delete
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    ReplyDelete
  29. Actually some cable companies do provide white papers for supporting their claims. E.g. https://www.qed.co.uk/downloads/qed/soundofscience.pdf

    I tried reading it, but am not an ee so didn't understand most of it. Archimago might.

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  30. Knowing very little about electricity (black magic) I find this all very interesting. What are your thoughts on line conditioners and surge suppressors? I would like to avoid them if I can, but am being sold on clean power and not blowing up my hear.

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    ReplyDelete
  32. It would be very interesting to see some time/impulse related measurements too, and possibly with some more highly regarded/known cables.

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  33. Caelin Gabriel of Shunyata
    Is thus the same guy with the patent which has a figure at a frequency 10 times higher than that stated in the text, something along the lines of a speaker cable having a different response at 100 kHz (like it matters) but the figure indicates the measurement was a 1MHz?

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    1. Well Gabriel is the Shunyata guy. Don't know the specific figure you mentioned but he (the folks) have quite a few acronyms and claims around special technologies:
      https://shunyata.com/technology-guide/

      Certainly even on that page we see all kinds of graphs on the microsecond scale and megahertz frequencies of questionable value to power cables and analogue audio!

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