Do Power Cords Make a Difference? A Compelling Demo from Shunyata

One of my first stops this morning—the first morning of AXPONA 2019—was the Shunyata room in the Renaissance Schaumburg Hotel. Shunyata, as you're probably aware, has long been one of the more scientific-minded of the companies focused on quality power for home audio systems.

I learned today that Shunyata has an expanding presence in the medical industry; It's actually a sister company, Clear Image Scientific. One graph displayed in the Shunyata room showed a huge reduction in noise in what appeared to be an EKG; see the image below. (Apologies for the poor image quality.) Look at the yellow trace, fourth from the top, and compare the top image (before) with the bottom image (after the application of Shunyata's noise reduction). I don't know exactly what you're seeing here, but the clarity of the signal has improved dramatically.

What really caught my attention though was a demo of one of the company's noise-absorbing cables, featuring Shunyata's Grant Samuelsen. Watch the following short video; it's only a couple of minutes long, and I promise it'll be worth it.

Wait—what just happened? The device Samuelsen is using—the noise maker—takes broadband A/C noise and makes it audible. The noise you're hearing is coming out of the hotel's A/C receptacle. When Samuelson plugs a noise-absorbing power cord into a spare receptacle, the audible noise vanishes because that broadband electronic noise has been so dramatically reduced. (With its orange color, this power cord is intended for the medical industry, but the same cable in a different color—blue—is available for your hi-fi. The price is around $350.)

Notice that the other end of the noise-absorbing cord—the IEC end—isn't connected to anything; it's just dangling. To put it in more technical terms, it's in parallel with the measuring device. When it's placed in series--inline--the further improvement isn't audible, but it is substantial.

This is not a direct demonstration that Shunyata power cords improve the sound of your hi-fi; for that you'd need to visit the show yourself, or try these cords at home. It is however powerful evidence that the Shunyata power cords are effective at reducing broadband noise in electrical circuits.

One problem I have with many high-end power cords is their weight and stiffness; it's common for IEC cords to pull out of the components they power due to their weight and stiffness--and power cords don't sound good when they're disconnected. But take a look at the image at the top of this post. That's a high-end Shunyata cord—this one costs around $1500, far less than the most expensive cords on the market--coiled up like a snake or a slinky. Apart from being flexible, it's also very lightweight.

COMMENTS
RH's picture

"This is not a direct demonstration that Shunyata power cords improve the sound of your hi-fi;"

And there's the rub.

That's what keeps all these types of demos, and the AC cable maker claims, so suspicious.

They never actually demonstrate AUDIBLE NOISE has been removed from AUDIO systems.

We can measure all sorts of things we can't hear. The Cable makers claim their cables make AUDIBLE differences against other cheaper power cables. So why don't we see evidence of people being able to detect this in blind testing?

For a cable to make sudible differences in the output of an audio signal, that entails measurable differences. So why don't we ever see from Shunyata or other manufacturers comparisons of of the AUDIO output (e.g. audio files/waveforms etc) of an audio system, showing measured differences?

This is why skepticism remains reasonable. They don't show:

1. Their AC cable producing measurable differences in the audio signal of a system.

2. That the differences are in fact audible in tests where sighted bias is controlled for.

ddps's picture

RH: You are astute here. This is because an amplifier's power supply does this job already.

What I find unfortunate about this is that people who fall for these demos are theoretically insulting themselves by insulting their choice of equipment. In other words, if you don't trust your manufacturer's power supply design in the first place, then why do you want to own the equipment you chose? It's almost impossible to design a power supply that is so poor that it *doesn't* already do what these filtering cables do. If you need a cable like this, it means that the engineers who designed your products were not worthy of the title.

CG's picture

Really?

You're sure about that, are you?

Then, this should be easy for you.

Please point me to a published test of an amplification or source component's noise floor where:

1. One or more tones are applied to the device under test. Ideally the tone(s) should be generated by a representative audio source component, not a test generator . (See number 3 below.)

And

2. The noise floor is NOT minimized through averages of multiple sweeps and other noise reduction techniques. Ideally, measurement techniques should be used to focus in on the noise floor.

And

3. The device under test is also connected to other typical components (in other words, a source, a preamp, and an amplifier) with the other products plugged into the AC mains and powered up. (This is to connect the common mode current paths typically found in an actual home audio system.)

I'll be happy to wait.

Full disclosure: I *do* have a connection to Shunyata.

Sometime back in the last decade, I purchased a Shunyata power cable from Music Direct, who was having an overstock sale.

The cable was clearly well built.

I installed it and gave it about two months of use to be fair. Some people would say that might be adequate time for "burn-in"; others might say that would give adequate time for my ears to "burn in" and adjust to my shiny new purchase.

Then I took it out and put the previous cable back in place. That was the end of the Shunyata cable in our system.

Clearly, my expectation bias system is completely broken.

Part two of the disclosure: I am not employed in the audio industry. My day job is in the telecommunications equipment biz.

Jim Austin's picture
Clearly, my expectation bias system is completely broken.
I am NOT going to get into an online debate about this--no time--but I must ask: What were you expecting from the Shunyata power cord? Were you expecting big changes? That's clearly relevant to assessments of expectation bias, no? My Best, Jim Austin, Editor Stereophile
CG's picture

I was expecting...

Nothing. By that, I don't mean that I was expecting no changes. I also wasn't expecting that it would be better or worse. Or just different.

I was completely open.

If the cable was better, great.

If it was worse (which it ended up being - at least to me), well, that sucks, but at least I gave it a try.

If it was just different, well then it would come down to whatever compromises I preferred.

In the end, it was easy.

Previously, I'd observed some power cords being superior, at least to me. Some others weren't as good. Others were a mixed bag.

My snide comment was based around the opinion held by many that power cords cannot possibly make a difference, and that I'd only hear a difference because I wanted the new shiny expensive toy to be better. It wasn't. So, obviously whatever expectation bias I have is non-functional.

Personally, I think being honest with myself is fundamental to doing things. I do that in my job. Why not here? Aside from my wife, who is a musician and gets an emotional rush from reading sheet music (not a lot of help...), I don't need to impress anybody else. Plus, I don't review gear, so I can choose whatever criteria for evaluation I want.

Kinda wordy, but I hope that answers your question.

BTW, my own measurements tell me that most audio industry measurements may be standardized, but aren't of much help, and that power supplies are not perfect and don't block noise currents. Especially common mode noise currents. But, others are certainly welcome to their own opinions.

And, although I'm not a fanboy of Shunyata, at least they're trying to measure what they can. Good on them!

Jim Austin's picture
This is a good comment--thanks for the reply. Not much in there to disagree with. As a trained (but not practicing) science, I get especially peeved at the closed-minded folks who wrap their biases in the cloak of basic scientific principles that they often they understand poorly. It's good to encounter someone with a mind that's appropriately skeptical but also open. That probably describes most audiophiles, but they're not the ones you see writing all the opinionated posts. Jim
CG's picture

I hope you're not expecting an argument from me. :8^)

While you're here... You might not be the right guy to ask, but I will anyway!

Why is it that somebody making observations over a period of a couple months, of, say, a piece of audio equipment is considered to be scientifically inferior to a group of people observing over a few hours?

In the first case, a single test instrument, imperfect as she or he might be, is observing the performance over a variety of conditions. That is, bad moods, lack of sleep, cold air, bad love affairs, Vogon poetry, you name it. Then, the accumulated observational data is "smoothed" into what is called an opinion.

In the second case, a number of test instruments, not only all imperfect but of different designs (genetics, early age learning, and so on) are observing something probably unfamiliar to them. Their accumulated observational data are then combined and "smoothed" into what is called a statistically significant result.

Huh?

I believe both Einstein and Feynman had somewhat skeptical comments about results based around statistics.

RH's picture

CG,

Your comment seems to be based on a very common misconception about sighted bias.

The misconception goes: "I wasn't expecting to hear a difference, but I heard one, therefore it wasn't due to expectation bias (hence any sighted bias)."

Or: "I expected the cable to sound better, but it actually sounded worse, therefore the effect couldn't have been due to expectation bias (which is then mixed up with sighted bias generally). Which means the audible change I perceived was true.

That isn't a remotely complete account of how we can come to misattribute what we (think we) hear.

The mere act of comparing what you know - or just think - to be two different items can itself be enough to get you to perceive a difference. That's why in blind tests you can tell people to report which they like when switching between A and B, and even if you are NOT ACTUALLY switching, but remain on the same "A," they can develop a "preference" for what they think they here with "B" (or A).

Listening for differences tends to get you concentrating in a way you don't normally concentrate and the mere act of changing your concentration around can influence the outcome.

It can happen completely unbidden, because for any number of reasons - tiredness, alertness, a particular mental or physical state, more intent, less intent listening, slight changes in listening position etc...you can "notice" something today you hadn't noticed before. "Hey,those trumpets sure sound richly burnished!" Especially to the audiophile mind, we will immediately think about an explanation "Well, what did I change last? Oh, those interconnects! Wow, I didn't realize they revealed that in the signal. Or...wow...they must have finally broken in!!"

It's just how human beings work. Really, just consider the utterly astounding number of dubious things people have become convinced they felt, experienced, heard, saw etc (attend a New Age Fair and you will find honest testimonies to the effects of every single wild device or nostrum sold. How does this happen? That's the way we are, a minefield of cognitive errors and biases. It's why science goes to great pains to reduce those variables.

This doesn't mean of course we should all turn our fun hobby in to a science demo every time we want to buy something new. But at the same time, if we really want to warrant confidence in certain claims, we can't pretend our biases are magically exempt just in our pet hobbies.

CG's picture

Let me try it again in a different case.

I WAS BEING SARCASTIC.

But, honestly, I'd be much more receptive to all this cognitive science with regard to audio reproduction if it really was based on looking at brain activity or something similar, instead of using statistical methods in an attempt to smooth out data from a bunch of very, very different flawed uncalibrated test instruments - human beings. You're basically taking the opinions of a bunch of people and molding them into scientific truth.

It's really easy and glib to just pat everybody on the head and tell them that what they observe is all in their head and not real. Especially, when somebody makes actual measurements of physical conditions - like noise on a power line - that conflicts with your own belief system.

Anyway, this is far too much like religion, and arguing over how many angels can sit on the head of a pin.

As far as the claims made by Shunyata, here is what I am certain of.

Power lines are dirty from external influences. These pass as differential (aka "normal") noise currents through the conductors. These are measurable.

Power connections also are conduction paths for common mode noise currents. These are far less well defined. The noise currents are also measurable.

Rather than have me try to explain all the subtleties of this, I suggest you consult Ott's and Morrison's books as two well regarded references on these subjects.

As best I can tell, very few - maybe no - manufacturers of audio equipment ever measure the effects of these noise currents on audio systems using their equipment. So, assuming that a proper power supply design eliminates these as potential sources of signal degradation is unproven, at least in the literature. Sheer conjecture and probably wishful thinking. You can find a ton of information on the topic with regard to electronic instrumentation, but good luck trying to find any with regard to audio.

Lack of supporting evidence does not mean that something does not exist. It just means that it hasn't been satisfactorily proven or explained yet. One way or the other.

Again, whether Shunyata's products work or not is not for me to say. My one exposure to them wasn't a success. I just find it ironic that a company is actually making the effort to explore actual objective measurements, and everybody just screams how that can't matter anyway.

RH's picture

I know you were being sarcastic. But you were making a point.

You're basically taking the opinions of a bunch of people and molding them into scientific truth.

What do you mean? You don't think human perception and perceptual limits can be measured? What do you think happens during a hearing test? And if you measured some area of brain function, how could you correlate it to experience without having categorized subjective reports from subjects to make the correlation????

Is it time for science to give up on any investigations that rely on communication from a subject? That sure would cut out a lot of science!

It's really easy and glib to just pat everybody on the head and tell them that what they observe is all in their head and not real.

Which is a straw man characterization. I'm not doing that at all. Someone COULD be hearing a difference between cable A and B - that's not ruled out a priori. But it's entirely sensible to recognize the variables involved, in trying to tease out reliable conclusions.
Again...that's why blind testing, placebo-controlled trials etc are used in many areas of scientific study.

Do we just imagine ourselves exempt from the contamination of bias effects in our hobby?

Especially, when somebody makes actual measurements of physical conditions - like noise on a power line - that conflicts with your own belief system.

I don't know what "belief system" you think I have, but I'm pretty sure you haven't got it right. How would being able to measure noise on a power line "conflict with my belief system?" If it's measurable...well..there it is!

If for an audio item, like an AC cable, a technical, measurable phenomenon is proposed as a problem, and that phenomenon is proposed to cause audible artifacts in the output of a sound system, and a company purports to have solved that problem, it makes sense to ask:

1. Do they have measurements showing the artifacts in an audio signal?

2. Can they demonstrate they have fixed this technical problem via measurements showing the before and after changes in an audio signal?

3. If so, is the measurable artifact in question *audible* (because measuring equipment can measure many things beyond the capabilities of our own senses - that's one reason why we invent measuring equipment).

4. What method have they used to determine the measurable difference is audible? Have they controlled for well-known variables such as sighted bias?

How are these not eminently sensible questions to ask, rather than some frothing at the mouth dogmatism? Should consumers just give up on critical thinking in the face of whatever claim a company wants to make to sell it's product....or is skepticism and critical thinking not a good tool to employ?

Lack of supporting evidence does not mean that something does not exist. It just means that it hasn't been satisfactorily proven or explained yet.

Yes. And doesn't it make sense to withhold a conclusion until it's been satisfactorily demonstrated? And doesn't it make sense to make sure there is a "there" there to be investigated in the first place?

Again: As I said, I'm not saying it's the consumer's job to turn every purchase in to a science experiment. People should buy whatever they want. But if we want to really look at claims made by people who want to sell us something, some good ol' critical thinking is in order.

CG's picture

Let's rewind some, shall we?

~~

"That's what keeps all these types of demos, and the AC cable maker claims, so suspicious."

The very first definition found when using Google to search for the word suspicious is:

"having or showing a cautious distrust of someone or something."

That certainly sounds like a bias to me. I could be wrong, of course. Frothing at the mouth dogmatism?

Just to be clear, I am NOT suggesting that all products do what the inventors and purveyors say they do or are worth the money they sell for, and certainly not for everybody. And, most certainly, an awful lot of the explanations are plain hogwash. But, how many folks would buy a product where the seller said something along the lines of, "We don't really know why it works. It just does for a lot of people. Perhaps you want to give it a try for yourself. As far as we, or anybody we have asked know, there is nothing harmful about using it."?

(By the way, conventional definitions of the word skepticism do not imply having an open mind going in.)

~~

"They never actually demonstrate AUDIBLE NOISE has been removed from AUDIO systems."

Absolutely true. But, don't you wonder why this is? If it was so easy and conventional to measure, wouldn't you think that either side of the discussion would have done this long ago? More on this in a bit.

~~

"We can measure all sorts of things we can't hear."

True! But, that does not imply that we can measure or do measure all sorts of things that we can hear.

~~

Not you, but somebody else who I probably should have addressed separately or specifically pointed to, then says:

"RH: You are astute here. This is because an amplifier's power supply does this job already.

"What I find unfortunate about this is that people who fall for these demos are theoretically insulting themselves by insulting their choice of equipment. In other words, if you don't trust your manufacturer's power supply design in the first place, then why do you want to own the equipment you chose? It's almost impossible to design a power supply that is so poor that it *doesn't* already do what these filtering cables do. If you need a cable like this, it means that the engineers who designed your products were not worthy of the title."

I'd actually agree with this. At least the part about power supplies not doing what the cables are doing. OK, only just a bit.

Power supply systems really should have great rejection of both incoming noise currents as well as outgoing noise currents. They are a big part of an extensive mesh of connections connecting components of the system together. You should only want the power supplies to conduct the 50/60 Hz AC power and nothing more. Do they?

Alas, they do not. In fact, in some situations for some kinds of noise currents, the power supply is not even part of the circuit.

Part of this state of affairs is because the problem is just pretty much ignored and thought to be unnecessary in consumer audio products. (And most everywhere else. The regulations regarding noise are way underspecified and easily gamed.) That's very convenient, isn't it? Saves money, time, product size and weight, and so on. Now, serious test gear and other instrumentation goes to far greater lengths to prevent the negative effects of power line noise. Even then, external filters are often employed to get adequate results.

To be honest, cables potentially only can perform modest filtering functions compared to bulk filters. However, what they *can* do is be designed and built in such a way as to minimize undesired field coupling of noise currents to other portions of the system. Unless you use battery power, you're going to be using power cables that connect to the AC mains. It makes sense to minimize coupling of noise currents in every way you can and therefore minimize noise transmission where you can.

The insult part, is, well, insulting.

~~

Now, back to the measurement thing as well as my earlier query.

I'd like to see examples of where the noise element of an audio system has been measured and published when multiple desired tones are used as stimulation and the test gear has not been optimized for displaying minimum noise. In other words, where the noise is the focus rather than the extraction of very low level distortion components.

Isn't this what you are seeking of as necessary proof? That and correlation of the noise to aural perception?

Lack of these measurements, by anybody, suggests to me that either nobody cares about this, for reasons I don't have an answer to, or that it's too hard to do with existing test regimes. If there's a third possibility, please tell me.

I'd think that might be characterized as good ol' critical thinking, eh?

RH's picture

That certainly sounds like a bias to me. I could be wrong, of course. Frothing at the mouth dogmatism?

You've got to be kidding. As I said I hold no a priori belief that AC cables can not make a sonic difference. I merely pointed out that I haven't seen good evidence - the type of evidence one should expect to be available if the claim is true. Giving good reasons for skepticism isn't dogma; it's the opposite. Just accepting the claims without question would be accepting dogma!

Then you suggest that maybe the lack of measurable results is due to the fact it's too hard to measure those results. If that were the case...then WHY WOULD WE ACCEPT THE POSITIVE CLAIMS MADE THAT THE CABLE MAKERS HAVE PRODUCED POSITIVE RESULTS???

And you seem to be special pleading on behalf of the cable makers. Remember, the phenomena they point to as the problem aren't magic - they are measurable phenomena which is why they purport to "know" what is causing unwanted artifacts in the first place! If they have identified measurable phenomena, claim to have fixed the problem...it's obvious the results *should be measurable*.

Which is of course why Shunyata wants to show you measurements sometimes.

The problem is that the measurements and demonstrations, do not verity their specific claims. Measuring at the AC outlet, or measuring a medical device, does not verify the claim that their product alters audio signals. Power supplies are there to deal with filtering out AC and other noise. If Shunyata and other AC cable manufacturers claim that, no, they have identified measurable artifacts that power supplies aren't able to filter out and that cause a change in the audio signal, then they should be able to directly support that claim by showing how their AC cable measurably alters an audio signal produced by a sound system - a before and after using their cable vs a stock cable.

How is this not perfectly reasonable to ask?

And, again, if you say "maybe it's just not something for which they can produce technical results demonstrating their claim" then of course....skepticism is warranted, rather than just accepting the claim.

And if you think no one has tested various claims made for various cables (and DACs) etc then you need to visit sites like Archimego's Musings (where he often tests claims via measurements), Audio Science Review, Hydrogen Audio. And of course the reason we have standards for producing competent cables, and power supplies etc is because they were developed through long histories of testing electrical theory!

CG's picture

I’ll try to be brief and take these in order.

Once again, lack of supporting evidence is just that. It works both ways. Nothing has been proven to be true or false. That does not mean a condition or situation does or does not exist. People happily used aspirin and its antecedents for more than two millennia before the mechanism was really studied or understood. (It’s still being studied, from what I can tell.)

I reviewed what I wrote and didn’t once suggest that you, or anybody, should accept any claims of any kind. If that statement is inaccurate, please point me to my error.

~~

Similarly, I could not find any instance where I took any side, never mind pleading, for any cable or any other makers. The only thing close was that I applauded Shunyata’s attempts at trying to quantify noise effects. Again, please point me to where I am in error about that..

~~

It may be perfectly reasonable to ask for most anything.

My point was, and still is, that I have not seen any examples of where an audio component, never mind a system, has been measured with a focus on the noise aspect when desired signals are applied. Every instance I’ve seen used techniques designed to minimize the effects of random and pseudo random noise in favor of picking out low level repeated signals like harmonic components.

If you have such examples, please point them out.

~~

Finally, about those web sites you refer to. I’m sure the folks there are genuinely sincere about their observations and beliefs. That’s not of question, at least to me. But, generally their view of flaws in electronic systems are pretty simplistic and focus on first order effects. Going into examples probably would be counterproductive here, but I’ll say that while their observations are often very accurate, as far as they go, they are definitely not complete. I don’t think I’d rely on them for complete resolution of questions like the one addressed here. But, what you do is up to you, not me.

Glotz's picture

Theoretical performance of a power supply is very different from actual. Shunyata does have tests proving audible noise has been removed from an audio system, as well as removing mains noise from hospital equipment, where the application is many times more important. It is also proven in listening.

I take it none of you have actually listened to a system (or tested one) with Shunyata power cables in place. Nor will you in the future, so the comments are pretty moot.

ddps's picture

Mistrustful? Guilty. Cynical? Absolutely not. That is a way of looking negatively at the world as a whole, and I don't play that way.

I come from a family of electrical engineers and learned all this growing up, first hand. A power supply cleans all of this up. That is one of the main purposes of a power supply! What do you think you pay several hundred dollars for in a good power supply?

Of course the Shunyata products filter as depicted in the video. I'm not arguing that. But "theoretical performance of a power supply is different from actual?" The engineers of most any power supply - and I know a mess of them - would beg to differ. Power supplies are designed and tested for this, and it's electrical engineering 101. If you don't trust the electrical engineers that design your products, then I propose you have a whole other set of things to deal with in your life.

And, per RH's point, nothing Shunyata has ever published shows its impact on noise - post-power-supply - in the audio chain. (https://shunyata.com/videos/)

The Shunyata cable followed by a power supply is a little like washing water with other water. Not like filtering water twice. But like washing water with other water. Anything the Shunyata does can - and will - be re-done by the power supply by definition.

RH's picture

Glotz,

Not only have I listened to systems employing Shunyata (and other boutique AC cables) plenty of times: I have had Shunyata cables to test in my own system. Several.

Two of them didn't seem to make any sonic difference at all that I could detect. But one did *seem* to alter the sound of my system.

Except I also took the further step most people don't bother with.
I did a blind test between a stock power cable and that Shunyata AC cable to help control for sighted bias. Once I did that...the sound was indistinguishable between the two cords. Most audiophiles it seems will never acknowledge the power of sighted bias.

Can you give a link to Shunyata proving AUDIBLE NOISE has been removed from an audio system?

In the past, it seems Shunyata's demos have been somewhat suspect.
For instance, Shunyata has a youtube video demonstrating the superior peak current capabilities of their cable over a stock power cable.

Some have pointed out that, of course the Shunyata presentation doesn't tell you they chose what seems to be a smaller 18ga stock AC cable to test against the higher 14ga Shunyata cable.

In other words: the measured difference shown in the video can be entirely attributed to the difference in wire gauge they chose to compare, not to anything otherwise special about the Shunyata cable.

If your power amp comes with heavier gauge AC cable, as many do (mine does) the Shunyata cable isn't going to make a difference in current capability, and in any case a 14ga cable can be bought for 20 bucks. You don't need to spend the gawd-knows-how-much-they-are-asking amount for the Shunyata cable to get the current benefits they attribute to their special cables.

(I'm no electrical engineer btw. I'm channeling responses I've seen from electrical engineers and various technically knowledgeable people who I have seen take on the claim of Shunyata and other cable makers).

Personally I like the idea of tweaking my system to higher performance like any other audiophile. I just find the lack of true, directly relevant data justifying the cable maker claims to be suspicious, and the general method of vetting their claims - sighted listening - to be unreliable for establishing the claims.

Glotz's picture

Theoretical performance of a power supply is very different from actual. Shunyata does have tests proving audible noise has been removed from an audio system, as well as removing mains noise from hospital equipment, where the application is many times more important. It is also proven in listening.

I take it none of you have actually listened to a system (or tested one) with Shunyata power cables in place. Nor will you in the future, so the comments are pretty moot.

And no, I don't believe anything you've written in your response, as there are several issues with continuity in your response. I assume you didn't hear lower noise floors, etc., with current capabilities being the same. You argue conveniently, so no, I won't continue to offer rebuttals.

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