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GR Research B24 AC Cord Review

Rate this AC Cable

  • 1. Waste of money (piggy bank panther)

    Votes: 323 95.0%
  • 2. Not terrible (postman panther)

    Votes: 4 1.2%
  • 3. Fine (happy panther

    Votes: 1 0.3%
  • 4. Great (golfing panther)

    Votes: 12 3.5%

  • Total voters
    340

amirm

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This is a review, listening tests and measurements of the GR Research B24 AC cable. I purchased it from the company direct. It costs US $349 in the 4 foot section I purchased.
GR Research B24 Power Cable Audio AC review.jpg

As the British saying goes, the B24 "looks the part" with the thick cabling and such. But fails in actual construction. When I attempted to first plug in the male end, it took incredibly force to push the earth/ground pin in. It it hugely oversized. It got progressively a bit better after a few insertions but then started to develop some scratches. Heaven knows what damage it has done to my outlet. Worse part was that when I first plugged it in, it was not passing any electricity! I look and it appeared to be fully inserted. Turns out it was not. There is this "shield sleeve" that slides forward pulling the heatshrink with it:
Audio AC Power Cord Review Shield fault Resistance.jpg


So looking from outside, it seems the plug has completely mated with the outlet. But in reality, hot and neutral pins have yet to make a connection. You have to simultaneously pull back the sleeve while attempting to push the whole contraption forward. Given the large force you need to put in there, it takes some gymnastics to be sure. This whole affair has gotten worse due to ground pin being too long:
Audio AC Power Cord Review Plug Too Long Ground.jpg


Compared to my other AC cords, the ground pin is 1 to 2 mm is longer. This means that even though you feel like you have inserted the plug into the outlet, you have not yet. I can see this being done to support the crazy weight of these cables but come on. An cable should be easy to plug in and not remotely have such issues. So big fail on usability.

Company advertising says that you can try the cable out and if you don't like it, you can return it and "get your money back." Close look shows that you are responsible for shipping it back, the cost of shipping it to you and unknown credit card charges. I payed $40 for shipping for 2-day service ($25 for standard ground). So if I ship it back the same way, I will likely incur some $80. For this much money, could have bought a dozen ordinary AC cables. So much for money back guarantee. :(

And oh, those Velcro cables are mine in the picture. It doesn't come with any. I have bought cheap Chinese cables that came with set of Velcros.

Company makes two sets of AC cables, the B16 and B24 series. These are the number of wires that are put in the cable (or per line?). Strangely, despite its lower effective resistance, the B24 is said to be more suitable for sources/pre-amps than power amplifiers! So that is how I tested it.

GR Research B24 AC Cord Basic Measurements
I am going to do things differently than usual, starting with some simple measurements of the AC cord resistance and then jumping into listening tests, before showing more measurements. Here is the resistance of the cable as a whole and comparison to a few others I had on hand:

Audio AC Power Cord Review Resistance.png


The large number of parallel strands creates a very low resistance cable. Total resistance was just 0.005 ohm or 5 milliohm. For later tests, I pitted the B24 against the worst opposite which was a generic and thin AC cable. It naturally had much higher (relative) resistance of 81 milliohm per meter (compared to 4 for B24).

If you pulled the maximum allowed 15 amps allowed out of the typical US outlet, you would get a voltage drop of 1.8 volt with my longer thin AC cable vs 0.08 volt for the GR Research B24. The former is just 1.5% drop which is negligible. Still, at 0.1% drop, the GR Research B24 clearly has lower resistance. The edge though drops substantially when you compare it to much cheaper aftermarket cables from Pangea and AudioQuest NRG-X3.

There are no regulator safety standards for the cable. The female IEC terminal has CE listing but the male end just says 15 amp/120 volt. Even if the latter was UL certified, the whole cable is not. So use it at your own risk!

GR Research B24 AC Cord Audio Tests
As a target, I used Topping A90 Discrete pre-amplifier. It has built-in power supply so accepts an AC cord directly. Switching from one cable to the other took too long to allow valid listening tests. Sometimes one cable would sound better. Sometimes the other. Sometimes they would sound the same.

Since you can't hear what I heard, I resorted to null testing. I used an RME ADI-2 Pro FS and looped its audio output through Topping A90 Discrete. Output of the A90D was then captured using RME's ADC. By using the same DAC and ADC, I removed clock variations, allowing for excellent nulling. Member @pkane 's excellent DeltaWave software was used to perform the matching.

First test was a classical record (CD) of Vivaldi's Four Seasons conducted by Christopher Warren-Green of London Chamber Orchestra:
GR Research B24 Power Cable Audio Null Test.png


The difference between output of the Topping A90D using generic thin AC cable and B24 was identical, resulting in just very low level noise at or below that of 16 bit CD content. Content is copyrighted but here is the difference file for you to listen to: https://www.dropbox.com/s/1qftq2r8bkw84hw/AC Power Difference.wav?dl=0

Next I tested the track Hunted from one of my favorite bands, Radical Face and their Missing Film album:

GR Research B24 Power Cable Audio Null Test Radical Face Hunted.png


On average we null down to the same -94 dB levels. If you listen to the difference signal, at extreme amplification, you can barely here tiny regular noise pumping. This is an artifact of the matching I believe than any audible difference. You are welcome to perform an ABX test as I can share the files here due to kind permission from the band: [youtube comment]

"Missing Film" is a selection of instrumental music I've written and recorded over the past two years. These tracks range from film and TV commissions that didn't pan out, to one-off experiments that have no home. Instead of letting these just sit idly on harddrives, I thought I would make these tracks available to film makers to use, royalty-free, in any of their personal work. So as long as it's non-commercial, you can use any of these tracks for your work and do not need my explicit permission. "

I chose to purchase the album though through bandcamp and I suggest you do the same: https://radicalface.bandcamp.com/album/missing-film

You can pay whatever you choose. Anyway, here are the clips and difference file:

Radical Face Hunted:
Generic AC Cable: https://www.dropbox.com/s/gj74weg67t2bwkh/Radical Face Hunted Generic AC Cord.wav?dl=0

GR Research B24: https://www.dropbox.com/s/7pft7ci37d4rbbj/Radical Face Hunted GR Research B24.wav?dl=0

Difference: https://www.dropbox.com/s/tpg17rdfjr1g5co/Radical Face Hunted Difference.wav?dl=0

I grabbed another track, I'll Be There Soon from same album which has different instrumentation:
GR Research B24 Power Cable Audio Null Test Radical Face I'll Be There Soon.png


This one nulled nicely and all that is there is noise even if you turn up the gain some 60 dB.

Here are the tracks again: Radical Face: Missing Film - I'll be there soon
Generic AC Cable: https://www.dropbox.com/s/v5dxg23j6rfeba3/Radical Face I'll be there soon Generic AC.wav?dl=0

GR Research B24: https://www.dropbox.com/s/33l12ajgaiphe8m/Radical Face I'll be there soon GR Research B24 AC.wav?dl=0

Difference: https://www.dropbox.com/s/ys5lva8w9bqghzl/Radical Face I'll be there soon Difference.wav?dl=0

Dropbox can play these files in place so you don't even need to download them. Just click on the links and play them in the new window.

Note that the tracks I picked above are some of my references for testing and enjoyment. They are superbly recorded and any difference in fidelity, should be obvious. There was none in my listening.

GR Research B24 Measurements
Company talks about how their cord "filters" other noise. Since your electronics performs strong filtering of its own, such a thing is not material. But for grins, I tested the worst case of treating the AC cable as an interconnect and putting a powered transformer right next to the cable:
GR Research B24 Power Cable vs Generic Noise Pick up Transformer.png


The GR research B24 is indeed less receptive to AC noise inducement. As shown though in green line, even if you used any of these AC cord as an audio interconnect, their noise still be inaudible!!! Of course, when used as a power cord, such induction will be beneficial as you would get tiny amount of extra power for free. :)

We don't listen to power cables directly though so let's plug them into Topping A90 Discrete again and see if its performance changes. Let's start with frequency response to detect tonality changes:
GR Research B24 Power Cable Topping A90D frequency response.png


None is there. While not shown, the result was the same with the other two power cords mentioned early in the review. I next ran our dashboard:
GR Research B24 Power Cable Dashboard.png


As expected, there is no change whatsoever. Performance is superb whether I use a cheap generic cable or B24. Before someone complains above is at one frequency, let's test at many and include ultrasonics in there as well:
GR Research B24 Power Cable Topping A90D distortion vs frequency response.png


There is not even a hair difference. Noise+distortion is below threshold of hearing even though we measure it out to 90 kHz.

Finally as a simulate of "music," let's test with 32 tones:
GR Research B24 Power Cable Topping A90D Multitone Music response.png


There is not even a slightest difference anywhere in any part of the spectrum with respect to noise or distortion.

I should say that my environment is quite "dirty." I have a workstation running these tests, an Audio Precision analyzer "polluting" the AC with its switching power supply. Half a dozen other devices from network switch to monitor and LED lamp is plugged in. An unterminated scope probe would show ton of airborne "interference" yet none is remotely impacting our audio device. Your situation in an audio system devoid of all the complexity of my system will be far less of a stress test.

Conclusions
We can naturally demonstrate through measurements that a monster heavy cable comprised of 24 individual cables does have lower resistance. And the weave is more resistance to AC noise pick up. As I keep saying though, we don't listen to AC cables, we listen to audio systems. Objective capture and nulling of the output shows zero difference brought to the table by the B24 cable. I have show three tracks. I am confident I can show you any number you want. Result will be the same. Sighted listening can yield "differences" but that can point to generic cable being "better" as well as the B24 depending on order, mood, amount of concentration, etc. Blind test will show no difference because we know objectively there is no difference (because of the null).

Of course as usual, our measurements of the output of the device show identical performance as well. In the past, I have pumped heavily distorted AC waveform into audio devices with no impact on them whatsoever. What hope is there that any "filtering" of an AC cable will make any difference? It can't and it won't.

Beyond lack of improvement on fidelity of the system, I am super disappointed by the build of this cable. It is just awful and I am not talking about the massive weight and stress it puts on your equipment and wall outlet. But rather the poor build of the male plug that works so hard against you being able to perform the simple test of just plugging it in! In that regard, I put any of the brand name AC cable products way, way ahead of GR Research work here. This is poorly done hobbyist work that has not stood the test of any independent evaluation.

While sadly a norm in aftermarket AC cables, the B24 lacks any safety testing. Who knows how safely they have stuff so many wires into its terminations. Who knows what happens if there is a short in your equipment and stress is put on this cable to trip your breaker.

Bottom line, I see no redeeming quality in GR Research B24 AC cable and so cannot recommend it.

Edit: video review posted as well:


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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
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amirm

amirm

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Grotti

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Excellent review! The suggestion to use it with sources is questionable: it would pull my little streamer right of the shelf (looks heavy and stiff). The reaction of my wife (just showed her the picture): she silently shook her head ;)....
 

pvehling

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What's the average gauge of modern Romex cable in the walls in the USA? Would using super low gauge power cords even matter if Romex cable gauge is higher? I suppose if you had to use a super long extension cord, the lower the gauge the better.

Edit: Just realized this cable is actually 14awg with a huge amount of insulation.. can get a Tripp-lite 14awg 3 footer for less than $7 :D
 
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ROOSKIE

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$349 for 4feet of this.
Maybe $15-20 in part costs.
That is the only measurement many sellers/manufacturers would be interested in. Well that and how many marks they can pull in.

Super fun review, thanks! Just love these tests of hoax gear as always.
 

xaviescacs

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Thanks. Fixed. It was fair bit of work but I wanted to leave little room for criticism. :)
:) I find the inclusion of the threshold of hearing particularly sound and clarifying. Does it makes sense to include it every time there is room for doubts about audibility of artifacts?
 
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martijn86

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If someone actually likes the benefits of low resistance, high noise rejection etc. - even if it is just for the peace of mind of using high quality components - you can look into outdoor, in-wall, PV, off-shore, live-event or marine cables for example. You can get the benefits of a heavy duty cable, without paying an arm and a leg for some uncertified DIY project.

I personally like to buy my own C13 cables, so I can get the exact length and connector angle. That just helps cleaning keep things looking tidy.
 
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voodooless

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Big ass cable should be used with big ass amp, no? Let’s get those 15 Amp juices flowing!

And as usual, @amirm didn’t read consider the description:

but the recommended burn in time for these to sound their best is 200 hours. So plug them in and get some time on them before making A/B comparisons.

No wonder you couldn’t hear any difference :facepalm:
 
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amirm

amirm

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And as usual, @amirm didn’t read the description:
I did actually. Just didn't want to spend that much on electricity after blowing so much on the cable itself. :)
 
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amirm

amirm

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What's the average gauge of modern Romex cable in the walls in the USA?
Minimum code is 14 gauge which means 15 amp outlets. 99% of the homes are wired this way. We ran 12 gauge in our home in our custom remodel. That gives you 20 amps.
 
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GXAlan

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:) I find the inclusion of the threshold of hearing particularly sound and clarifying. Does it makes sense to include it every time there is room for doubts about audibility of artifacts?

It will be hard to retroactively go back and add this to every review but it is a nice thing to add going forward. It helps me understand what I am hearing from my PM-90 where a lot of the distortion is below threshold except for some 2nd order harmonics.
 
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