GR Research B24 AC Cord Review

[Spkrdctr]

Regulatory marks on the cord caps and the cord does not mean that the assembly is listed or approved.

I can go to the hardware store and buy a bag full of Regulatory agency marked parts and assemble some sort of contraption in my basement and still have a unlisted contraption on my bench.

To be listed or approved that contraption needs to be packaged up and sent to the Regulatory agency test lab for testing. This test lab approval process is not cheap.

Thanks DT

You are correct. It is not cheap!

 

[Lambda]

Can you explain this? Any testing you know of to back it up?

Electric or magnetic feeds radiated from the cord and pieced up by a sensitive analog source with low voltage and high impedance.
For example Phono or realt to real.

it's admittedly a contrived scenario. but not as much as using the power cord as interconnect for a undisclosed signal level.
and trying to make statements about auditability from this measurements.

don't get me wrong i don't say the cable makes a(audible) difference.
But i don't know/can't say this from the testing

But everyone familiar with the scientific method knows about the inherent problems of proving a negative.

 

[MerlinGS]

Electric or magnetic feeds radiated from the cord and pieced up by a sensitive analog source with low voltage and high impedance.
For example Phono or realt to real...it's admittedly a contrived scenario.

Considering these PC are rarely if ever marketed for phono or reel-to-reel, and even less likely used for that purpose, it is truly a contrived scenario. However, interconnects can have a role in phono systems (total capacitance can have an effect on the performance of a MM cartridge).

 

[DualTriode]

What this review / test thread and my experience on the test bench indicates to me is that power cords can leak EMI in both directions. Stuff can both leak in and leak out.

On my bench I am always fighting power line harmonics even in battery powered discrete FET line level amplifiers.

testing in a shielded enclosure helps. Shielded AC power cords also seems to help some.

$350 shielded cords no.

Cords like this, yes. UL? Yes.

Amazon.com: Grey Shielded Power Cord by Safe Living Living Technologies Inc. (6 Feet) : Electronics

Amazon.com: Grey Shielded Power Cord by Safe Living Living Technologies Inc. (6 Feet) : Electronics

www.amazon.com

 

[Lambda]

Considering these PC are rarely if ever marketed for phono or reel-to-reel,

it's also not marketed as analog audio interconnect and even less likely to be used for this.
Also it don't has to be marketed or even used for this it’s magnetic / electric fields can influence. analog sources in the vicinity.

I'm sure most of us have herd a "hum" that got somehow piced up by an audio system.
So audio systems picking up mains mains noise is not that rare

If there is less "hum in the air" (close to the sensitive components like like analog sources preamps or tube amps) the system can pick up less hum.

In this test the cable seams to have ~20dB less Noise pick up. (we don’t know how it was tested so this number don’t tell a lot but lets go with it
Assuming it has also 20dB less emission and most of the noise the system is picking up comes from power cables near by.
The system could have up to 20dB less Hum making it in some cases Inaudible.

Sure 20dB is very unlikely but maybe 3dB is not impossible in the right scenario.

(not impossible != likely)

 

[amirm]

I'm sure most of us have herd a "hum" that got somehow piced up by an audio system.
So audio systems picking up mains mains noise is not that rare

And I am sure chances of that being solved by buying one of these cables is zero.

I have read countless reviews and testimonials for cables. The standard claim is always removable of veils, blacker background, less or more forward treble, tighter bass, etc.

And it is not like you or manufacturer ever show such a scenario with measurements anyway. You all make the claim hoping the layman buys the argument. Well, it doesn't work here.

 

[DonR]

And I am sure chances of that being solved by buying one of these cables is zero.

in my experience, 99 times out of 100 the hum is usually a ground loop.

 

[Lambda]

And I am sure chances of that being solved by buying one of these cables is zero.

And that's a scientifically proven fact backed by the measurements or a gut feeling/educated guess?

And it is not like you or manufacturer ever show such a scenario with measurements anyway. You all make the claim hoping the layman buys the argument.Well, it doesn't work here.

And it is not like you have proven it’s impossible. You make the claim hoping the layman buys the argument.
In fact your own measurements show the cable has less magnetic Pickup/emission.

If this makes a difference depends on whole rest of the system tarts out of your control.
You can’t test every system combination and even if this is no "proof".
It is inherently problematic to proof something don't exist or is impossible.

Whit Reasoning and knowledge about Physics and Electrical engineering.
We can easily come to the conclusion that the power cable mask now f**** practical difference at al.
Whit Reasoning we can prof it can't fix anything if nothing is broken.
So we can come to the conclusion there is no Magical improvement possible.
what is "blacker background, less or more forward treble, tighter bass, etc." even supposed to mean how would it show up in the measurement?

But showing some unrelated ,unrealistic, undefined or out of context measurements hoping it helps the layman buys the argument...
This is pseudoscience and snake oil salesmen marketing methods.

 

[amirm]

And that's a scientifically proven fact backed by the measurements or a gut feeling/educated guess?

First of all, don't accuse me of what you are doing. You said such hum is "rare" but happens. Yet you provided zero evidence of that.

Every other day I test something with potential mains interference/ground loops. When exhausting every other option, a number of times I have relocated power cords, or changed them altogether with zero impact. I also told you about considerable experience I have reading people's experiences in this regard, with no such observation.

You put your hypothesis forward without any of the above, and I returned the favor except with much more behind my guess. So again, don't throw nonsense at us.

 

[amirm]

But showing some unrelated ,unrealistic, undefined or out of context measurements hoping it helps the layman buys the argument...
This is pseudoscience and snake oil salesmen marketing methods.

What I am reading from you is that. You don't even have a single piece of evidence for anything you keep saying here. Didn't you at one point promise me data in two weeks on some argument we had on power conditioners? That was months ago, right?

My testing was right on the money. I showed evidence of magnetic coupling into a cable. I showed that this cable actually has merit in this regard. The test was fully documented with instrumentation and scenario. It can easily be replicated. And the science of the wire construction backs it.

What I am reading from you is FUD and general nonsense. You say hum can be created by using the wrong cable. Where the heck is the back up for that? I say hum can be picked up and I show you this:

You see the mains and its harmonics? This is data. It is 100% solid data. Not conjecture and imagination hoping to land points with the uninformed.

Oh wait, you don't know the amplitude of the magnetic field? What the heck difference does that make in an AB difference between two cables? It doesn't.

Furthermore, a transformer being placed right at the cable and rotated for maximum interference is by far the worst case scenario than any audio AC cable experiences.

Finally, the foundation of this review was listening tests. Everything you say is wrong in the context of nulling audio that is dead silent. You want to valid raise objections? Read and understand the review first.

 

[Lambda]

You said such hum is "rare" but happens. Yet you provided zero evidence of that.

I did honestly not think that's controversial and needs proof.

here is a phone preamp picking up hum:

 

[amirm]

I did honestly not think that's controversial and needs proof.

here is a phone preamp picking up hum:

Are you serious? Where is the proof that the AC cord was the problem here?

It is precisely in these situations that I play with AC cords to see if they have an impact. They do not. Switching power supplies have Y caps in them that happily pass through mains interference. You can swap AC cables all you want and it won't make a difference.

You are just wasting our time.

 

[tomchr]

Can you explain this? Any testing you know of to back it up? Is it only with exotic poor performing equipment? Does it involve any normal regular mainstream, not boutique products? Thanks for any info.

I already did:

The only case where I think a different power cord could make a difference is if the 'upgrade' power cord is one of heavier gauge wire. In a single-ended system, such as most residential audio systems, that would result in a lower impedance ground between pieces of equipment, which can result in a lower error voltage between different pieces of equipment, thereby lower noise and hum. Bruno Putzeys' article, "The G Word" is a good primer: https://www.edn.com/the-g-word-how-to-get-your-audio-off-the-ground/
But even in that case, it's the wire gauge (cross-sectional area) and possibly the quality of the connectors that matter. Not whatever bling is added to the cord.

Note that this applies only in single-ended systems. If you're using differential links between components you won't see much any difference. Or at least any difference (which is small anyway) will be attenuated by the CMRR of the differential receiver, which tends to be high within the audio band.

And you don't need a fancy power cord either. You can buy 6 AWG grounding wire at Home Depot for not much money and just tie your pieces of gear together with that. That'll have the same effect.

Tom

 

[Lambda]

The test was fully documented with instrumentation and scenario. It can easily be replicated. And the science of the wire construction backs it.

Sure can you point out where you documented:
1. the used signal level for the 1khz signal.
2. how the cable was set up as a balanced or unbalanced interconnect
3. with what source and sink impedance.
4. if sink and source share she same ground or if thy are only concreted to the cable
And of cause all the FFT / windowing / bandwidth settings.
just in cases someone wants to replicated it.

Where is the proof that the AC cord was the problem here?

You asked for proof of hum in systems
If you want proof that analog interconnects can pick up noise emitted by power cords i would recommend this video

 

[amirm]

It is inherently problematic to proof something don't exist or is impossible.

It is not. We do it day in and day out in science and in real life. It is a fallacy and high-school debating line to say what you did. Those of you who make this false argument are in dire need of reading this short article from professor Steven Hales: https://www.cambridge.org/core/serv...f/thinking-tools-you-can-prove-a-negative.pdf

"But there is one big, fat problem with all this. Among professional logicians, guess how many think that you can't prove « a negative? That's right: zero. Yes, Virginia, you can prove a negative, and it's easy, too."

Remember, in many cases we can't prove a positive either. We simply gather enough evidence to feel good that the positive proof exists. Same is true of negative. There just needs to be enough compelling evidence that a negative proof is made. If I asked you if you exist, you say yes. Maybe you are a robot and don't really exist. But we take it that you do exist. Therefore the proof that you don't exist (a negative) is also made.

You drink bottled water and think it is safe to drink. Yet no one has tested that exact bottle you are drinking. Maybe it is not and you are going to get sick from it. You go about your life not worrying about that. By the same token, when I show you listening tests, explanation of engineering, measurements, etc., the complete position absolutely proves a "negative." That there is no audible effect with this cable.

So don't throw lines at us like this that only gets used to debate with zero value. Save us the nonsense.

 

[amirm]

I already did:

And that would be wrong. By far the main cause of ground loops is due to interconnect shield impedance. You can have zero impedance to the wall outlet on the AC cord and it won't help you maintain two identical grounds in equipment due to localized leakage in the unit itself. Go ahead and swap AC cables and see if your hum goes way. It never does or we would be recommending this to people left and right.

The best authority on this is Bill Whitlock. He covers this in countless articles and presentations. Here is one:

" In any case, a small but significant ground voltage difference (1 volt is not unusual) will exist between the chassis or local “ground” of any two pieces of safety-grounded equipment. We must also accept this fact as reality."

All those stray capacitances that I have highlighted cause leakage to the chassis causing that differential. You know this full well yet make a different argument? So disappointing how far you have fallen from position of speaking the truth about audio.

 

[amirm]

If you want proof that analog interconnects can pick up noise emitted by power cords i would recommend this video

Now you don't even know your own argument. I just showed you that I can induce noise into a cable. That was not the question. The question was whether the AC cable can help with hum as you claimed to be true but "rare." You have zero evidence of your own to back anything you say.

 

[USER]

Oh my goodness with these second rate engineers.

 

[Lambda]

Sure can you point out where you documented:
1. the used signal level for the 1khz signal.
2. how the cable was set up as a balanced or unbalanced interconnect
3. with what source and sink impedance.
4. if sink and source share she same ground or if thy are only concreted to the cable
And of cause all the FFT / windowing / bandwidth settings.
just in cases someone wants to replicated it.

still waiting for this data....
Can't find it in the review

And if someone thinks you can see absolute amplitude measurements in an FFT without any knowledge about the FFT progressing or the test signal ( in this cases Mains Noise)

https://kluedo.ub.uni-kl.de/frontdoor/deliver/index/docId/4293/file/exact_fft_measurements.pdf

. I just showed you that I can induce noise into a cable. That was not the question. The question was whether the AC cable can help with hum

if the Power cable close to the signal cable emits less Electrical or Magnetic fields alls things equal the signal cable picks up less of it.

 

[JanesJr1]

It is not. We do it day in and day out in science and in real life. It is a fallacy and high-school debating line to say what you did. Those of you who make this false argument are in dire need of reading this short article from professor Steven Hales: https://www.cambridge.org/core/serv...f/thinking-tools-you-can-prove-a-negative.pdf

"But there is one big, fat problem with all this. Among professional logicians, guess how many think that you can't prove « a negative? That's right: zero. Yes, Virginia, you can prove a negative, and it's easy, too."

Remember, in many cases we can't prove a positive either. We simply gather enough evidence to feel good that the positive proof exists. Same is true of negative. There just needs to be enough compelling evidence that a negative proof is made. If I asked you if you exist, you say yes. Maybe you are a robot and don't really exist. But we take it that you do exist. Therefore the proof that you don't exist (a negative) is also made.

You drink bottled water and think it is safe to drink. Yet no one has tested that exact bottle you are drinking. Maybe it is not and you are going to get sick from it. You go about your life not worrying about that. By the same token, when I show you listening tests, explanation of engineering, measurements, etc., the complete position absolutely proves a "negative." That there is no audible effect with this cable.

So don't throw lines at us like this that only gets used to debate with zero value. Save us the nonsense.

Science logician Karl Popper famously gave the analogy that proof by accumulated positive evidence is weak or no proof; but that falsification (the telling negative) can be proof of the antithesis... Such as when it was believed that all swans were white, by evidence of the millions of white swans seen since the dawn of history, and which was disproved by the first black swan discovered by Westerners in the far east. It just took one black swan to destroy the premise.

It seems to me that by repeatedly testing cables, you (Amir) are looking to find the black swan for the cable magicians; that is, the single case of a cable that improves performance by means of materials or construction (and not by eliminating ground loops or other known commonplace technical phenomena unrelated to the cable magicians' unproven speculative theories). You can probably never PROVE that cables can't ever help by accumulating all these snake oil cases, but by using scientific method you are denying the cable magicians of the black swan that would prove their case (that is, a cable that affects performance). You are exposing their lack of science. Shifiting public opinion with the weight of induction (if not logical proof) will be your reward. The absence of evidence will still be taken as evidence of absence (at least by many).

(In other words, I'm not sure I fully agree with the article you referenced, but no matter: I think/hope that you will win the war if not every battle.)