Objective measurements for power cables???

amirm · Dec 5, 2010

Nordost claims they are on a path to have them. This is a long, almost one hour presentation. But worth a look. Skip the early junk about math and such. It is all non-sense as there is no "math" involved in anything they measured or talk about.

http://audiofest.net/2010/video_player.php?video_id=10&Sid=10c06a43bf211482677cce015fb162ea

rblnr · Dec 5, 2010

Will take a look at the above. Shunyata is touting a new method of measurement too:

http://shunyata.com/Content/DTCD.html

amirm · Dec 5, 2010

I have seen those. The difference is that the Shunyata tests are much easier to dismiss (look at the amount of current they attempted to pulse into the cable).

amirm · Dec 9, 2010

It is definitely a good attempt to come up with a set of charts that they can put up with a straight face.

For those without the time to sit through this, they use a PC to capture the audio samples while they replace power cables and such on the CD player. And they show differences such as noise floor or difference from what was data was on the CD and what was captured.

For me, I would have wanted to hear more about the capture device. They called it a sound card. But no brand, etc. How do we now how repeatable that data was? Since the PC itself is powered presumably with an ordinary cable, how was it able to achieve better noise performance than the device under test? A much better path is to use an Audio Precision analyzer so that least others could repeat the results.

The other thing I found negative was the fact that none of the people designing cables had thought about using such a simple test methodology -- one that has been used in many circles including on Computer Audiophile. They sound like they don't use any instruments, nor do they understand the reason behind the observations. I find both of these rather disturbing.

amirm · Dec 9, 2010

I don't know that we know for sure that distortion was reduced. The PC is interacting with the source being measured as it is electrically connected to it. It has its own noise that it could be injecting into it due to ground loops which could change when power cables were swapped.

In any measurement, we need a control. They lack such a control. If they used a trusted device like AP which we know to be a good design, then that would be one thing. But not taking a PC, sticking a sound card into it and calling it an instrument. By definition they are saying that PC, with an ordinary and noisy power system is superior to the CD player being measured. That could very well be but they would have to first prove that.

Phelonious Ponk · Dec 9, 2010

Skip the early junk about math and such. It is all non-sense as there is no "math" involved in anything they measured or talk about.

And so you would continue watching beyond this point because?.....

taking a PC, sticking a sound card into it and calling it an instrument. By definition they are saying that PC, with an ordinary and noisy power system is superior to the CD player being measured.

Ah.

Tim

amirm · Dec 9, 2010

Well, the set up is that one of the cable guys runs into a physicist working for a company building sonar and such. They talk and he speaks math to the level they don't understand and suggests that they have analysis methods that audio people are not using. And they go on to say that the two presenters will attempt to bring the math down to the level that everyone can understand. But as I noted, what follows are mostly time domain measurements of samples and comparing them (before/after). No math is ever shown or talked about.

In that sense, there were no smoking guns to get me to stop watching as if there were math, I was interested in what it was. I should say that it is definitely a worthwhile thing to watch. As much as I picked on it, there *appears* to be something there.

Ethan Winer · Dec 9, 2010

Phelonious Ponk said:
And so you would continue watching beyond this point because?.....

That's exactly what I would have asked if you hadn't. Hey, I produce educational videos too, and if it took me an hour to make a single point I'd be rightfully embarrassed. This video explains the basics of programming analog synthesizers in only 20 minutes:

http://www.youtube.com/watch?v=NMF8F9z7Zr8

If think a video "proving" that power cords improve audio quality of the connected devices could be 5 minutes long or less. Show an FFT of Before and After and you're done.

This research from Cornell University shows that liars use 35 percent more words than those telling the truth:

http://www.news.cornell.edu/chronicle/04/10.21.04/online_liars.html

So you can imagine what I conclude when someone uses 1200 percent more.

--Ethan

Phelonious Ponk · Dec 9, 2010

As much as I picked on it, there *appears* to be something there.

There may be. I am, nonetheless, amused by, "It is all non-sense as there is no "math" involved in anything they measured or talk about." Not to mention it has the added benefit of reinforcing my expectations.

Tim

Phelonious Ponk · Dec 9, 2010

tomelex said:
Actually, I think it is well worth watching and listening to understand . To me, the essence is that by hanging a big old heavy power cord on your cd player you dampen it, and that there is measurable less smearing of mid high to high frequencies when you do this. In the end this program shows how mircophonic vibrations are affecting the cd player and their measurments as far as I can tell show the proof of this.

I am not convinced that there is anything other than the weight of the power cord as far as its effect. Perhaps (theoretically in my book) some filtering is going on there though, which is possible for a power cord to do...I do not know the details of their power cord.

I put it all down to damping the mechanical parts in the cd player, FROM its own internal vibrations, NOT even those induced by music, as in the testing at the UK defense lab I do not think they were actually running speakers....

Tom

Right. But it would be simpler and a lot more efficient to just sit a brick on top of the thing.

Tim

mep · Dec 9, 2010

I am not buying the explanation that the power cord is adding mass that damps the chassis and that causes any type of sound improvement. Really, how much mass at the IEC connector can the plug add?

andy_c · Dec 10, 2010

I'm amazed that anyone would take these guys seriously. They do the "please don't ask questions until the presentation is done" thing so they can control the spin. I would have immediately asked, "Why do your graphs of the error signal not show any vertical axis scaling?". Also, Roy Gregory is saying of the demo, "You will hear...". Wow. Shameless.

The reason the error signal increases with the time derivative of the signal being sampled is that they did not accurately take into account the delays through the measurement system. The freeware Audio DiffMaker by Bill Waslo does this right. A key element of doing it right is performing sub-sample time shifting via Fourier transform techniques. IOW, one is not restricted to shifting samples by integer increments of the sample period in order to get the deepest null. The null they show is less than 20 dB, a reflection of a poor measurement technique.

amirm · Dec 10, 2010

I noted that as I was watching but that doesn't explain the effect of cables and then cable+box reducing the differential. Of course, this assumes they repeated the exercise.

And yes, their way of presentation reduced the credibility of what they were showing.

FrantzM · Dec 10, 2010

amirm said:
<snip>
And yes, their way of presentation reduced the credibility of what they were showing.

No surprises there.. The only one is how much we are straining to find explanations with something which is not reliably perceived under strict protocol.. In all this that begs the question: .. If you don't know how it works how in the world did you manage to design it?

rblnr · Dec 10, 2010

In all this that begs the question: .. If you don't know how it works how in the world did you manage to design it?

I once asked this of a prominent cable designer but put it a little less bluntly. I was given the analogy of how penicillin was discovered by accident. I chose to let it go at that point.

amirm · Dec 24, 2010

I think it is because it requires good bit of time to watch it. Our attention span these days is too short

. Sad though as whether you believe in what they are doing or not, it is a worthwhile thing to watch.

garylkoh · Dec 24, 2010

I sat through their presentation at last year's RMAF. Then, Joe Reynolds, Roy Gregory and Steve Elford came to my room and we had a rather extended discussion. *Disclaimer - I was using all Nordost cables in my demo system that year*

Roy is the marketing guy, but I felt that Steve really knew what he was talking about. At that point, Vertex and Nordost were competitors, but they shared a common goal to understand better what they thought they knew. The skeptics will dismiss the cable snake oil vendors, but I though that they were on to something new, until I did more research and found a lot more references to time domain measurements. Some of these have been posted elsewhere on this forum.

Steve told me the name of the company that was doing the measurements for them, but I can't remember what it is now. I did a quick google search then, and they seemed to be what Steve said that they were - a British military contractor specializing in some very esoteric signal processing work with sonar. I'm very sure that they did not just stick a sound card into a PC to do these measurements. One of the things that Steve told me was that the reason that they needed those guys to do these measurements was that they were doing things that were beyond Vertex's or Nordost's ability to measure.

amirm · Dec 24, 2010

Boy, I love the Internet! And its search engines.

After hunting around for a while, I found their consultant, his report at his company web site! It is a much easier read than sitting through that power point presentation. And of course, the text is far more readable: http://www.acuityproducts.co.uk/Case Study 1 - Vertex.pdf

Alas, it still doesn't say how he captured the audio. It does say the capture was at 44.1Khz which makes me believe it is an audio capture card, not some other data acquisition device.

amirm · Dec 24, 2010

And the second report is here: http://www.acuityproducts.co.uk/Case Study 2 - Quantum.pdf

This is the company web site. Seems like testing audio equipment is a commercial venture for them! I suspect they got paid to do this report: http://www.acuityproducts.co.uk/index.html

Phelonious Ponk · Dec 24, 2010

amirm said:
And the second report is here: http://www.acuityproducts.co.uk/Case Study 2 - Quantum.pdf

This is the company web site. Seems like testing audio equipment is a commercial venture for them! I suspect they got paid to do this report: http://www.acuityproducts.co.uk/index.html

That's a reasonable suspicion. Of course getting paid to test and report doesn't preclude you from doing it well or objectively, but I still have my doubts. Audible difference in signal cables? Sure, though I still suspect the cables you can hear are usually doing something wrong. Power cables? It just doesn't make sense. There are miles of pipe from the filtration plant to your house, yet that last few feet to your faucet, no filter involved, makes it taste different. Wouldn't you simply conclude that some sediment in that pipe was coming out in your drinking water, rather than believe that last two feet of copper is magically purifying it? Of course you would. But if it is audio....

Tim

Objective measurements for power cables???

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