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Power cord blind test

Found this video posted recently on Youtube :

YouTube Video ID: Bqp4oUff4XE

What do you guys think? Any criticisms?

Re: Power cord blind test

Reply #1
So when is he upgrading the wall outlets and house wiring?

Better yet, is he also gonna build his own power station?

The only signal a power cable transmits, is a 50Hz sine wave of 325V peak-to-peak (at least where I live).
Scraping the barrel of the bottom here, with presumably the worst cable he could find, I'd assume it simply attenuates the the 50Hz signal. Possibly not even the actual conductive material, rather the interface of the connectors on both ends.

Furthermore: he's using a 20k USD Amplifier? Then how is that expensive amplifier's PSU not built such that it can buffer enough power for whatever output it needs? When I'm getting a premium amplifier, I'd at least expect it to be able to built well enough to work with whatever power you supply it with.
In fact, if the cable has such an obvious impact, that you can hear it through six or so re-encodings on Youtube, then the impact on a cheap amplifier could be easily audible as well. What he exemplifies in this video, is that his Amplifier is fussy about power cable attenuation, which I think is a pretty bad sign.

Oh right, if he's such triggered by it all: Why even have connectors at all? All he has to do, is just directly wire every single device in his setup from a DC source, bypassing the internal PSU. An assortment of high-current batteries would do, using high amperage wires, or better yet, bus bars. This would ensure there's no AC to DC conversion inside his devices going on.

Seriously though, he just probably needs to clean off some corrosion on the cheapo cable to make it on-par with the expensive one. And while he's at it, he might wanna clean the connectors inside his amplifier's PSU, too.

Re: Power cord blind test

Reply #2
Apart from all the (correct) assertions above in polemon's post, I can see (hear) some other issues.

The first track has audible differences in level and channel balance between A and B. This suggests that the amp is susceptible in each channel, differently, to supplied AC power (assuming you accept there is indeed a difference from the power cord). Alternatively, maybe he's not so careful about level-matching as he claims or his microphones got moved or whatever.

Additionally, the test is not double-blind and is, therefore, near-useless. It's also flawed in the assumption that such an expensive amplifier is automatically beyond reproach, which is by no means guaranteed.

EDIT: typos

Re: Power cord blind test

Reply #3
The poster appears to have registered for the sole purpose of promoting this video, and from what I can check, they've restricted playback to everywhere excluding the US. I'll alter the post so the link is slightly obfuscated, and restrict their account.

E: Restricted in Australia as well, so I can't use my only out-of-US VPS to retrieve the video.

Re: Power cord blind test

Reply #4
Pretty sure it's been restricted in those countries due to copyright restrictions, though. The music samples that they used would render the video blocked.

Seems they've been doing this for six years now. It's your pretty average Audiophoolery channel, imo.

 

Re: Power cord blind test

Reply #5
The poster appears to have registered for the sole purpose of promoting this video, and from what I can check, they've restricted playback to everywhere excluding the US. I'll alter the post so the link is slightly obfuscated, and restrict their account.

E: Restricted in Australia as well, so I can't use my only out-of-US VPS to retrieve the video.

Sorry, I didn't know the video was blocked for US viewers. I saw this video posted on Youtube thinking maybe there was some substance to it, but I'm not technical enough to find discrepancies. Long time lurker, and I know many guys here are very knowledgeable about testing, hence the posted video to see what you guys thought.

I find it highly unlikely a power cable could influence the sound over a Youtube clip (using headphones, I could certainly hear a difference) unless something else is going on. Maybe the reviewer fudged the recording in some way?

Re: Power cord blind test

Reply #6
The poster appears to have registered for the sole purpose of promoting this video, and from what I can check, they've restricted playback to everywhere excluding the US. I'll alter the post so the link is slightly obfuscated, and restrict their account.

E: Restricted in Australia as well, so I can't use my only out-of-US VPS to retrieve the video.

I'm not promoting the video, I just wanted community feedback as to whether the reviewers claims had any merit.

Re: Power cord blind test

Reply #7
I just wanted community feedback as to whether the reviewers claims had any merit.
These things have been discussed to death and back.

Small measurement are almost always measurable, even just changing the ambient temperature often is. Does that mean that it is impactful? Maybe. So what is his "ABX" test? Well, it shows that his amplifier or whatever, behaves differently depending on the power cord he uses. However his sample size is just two chords, he has no base value. Technically, he proves, that some amplifier/power chord combinations don't work well. Which one those are, is unquantifiable at this point.

The possibilities how this impacts the range of the amplifier is actually kinda interesting. I can only guess, but assuming his "test" isn't faked, there seems to be predominantly a resistance issue of some kind. Most likely, this is due to dirty pins on either end, increasing the interface resistance.

His conjecture is, that you can buy better sound with a more expensive power cable, which lends you to all sorts of audiophoolery. Either do a proper test of a range of cables, or don't. If anything his test only exemplified, that one of the cables has some sort of issue, perhaps.

Re: Power cord blind test

Reply #8
This is hilarious. What is missing here is a vinyl player. The sound is missing the analogue feeling. Even 4k GBP can't compensate for that.

Re: Power cord blind test

Reply #9
I just wanted community feedback as to whether the reviewers claims had any merit.
These things have been discussed to death and back.

Small measurement are almost always measurable, even just changing the ambient temperature often is. Does that mean that it is impactful? Maybe. So what is his "ABX" test? Well, it shows that his amplifier or whatever, behaves differently depending on the power cord he uses. However his sample size is just two chords, he has no base value. Technically, he proves, that some amplifier/power chord combinations don't work well. Which one those are, is unquantifiable at this point.

The possibilities how this impacts the range of the amplifier is actually kinda interesting. I can only guess, but assuming his "test" isn't faked, there seems to be predominantly a resistance issue of some kind. Most likely, this is due to dirty pins on either end, increasing the interface resistance.

His conjecture is, that you can buy better sound with a more expensive power cable, which lends you to all sorts of audiophoolery. Either do a proper test of a range of cables, or don't. If anything his test only exemplified, that one of the cables has some sort of issue, perhaps.

I see Alan Shaw from Harbeth has recently commented on this video as well and found this upon closer inspection using Audacity  :



The waveforms are very different. There seems to be a channel imbalance, which invalidates the "test" outright.

Re: Power cord blind test

Reply #10
Doing any sort of "analysis" on the material that's available on Youtube is meaningless, because it's simply re-encoded over and over many times. If you want to do a proper analysis, you'd need a test setup, and have the object under test being measures such that there is only one variable.

Re: Power cord blind test

Reply #11
Most likely, this is due to dirty pins on either end, increasing the interface resistance.
"dirty" could be "corroded". Bring out your silver polish. And if one is corroded, it is probably the one from from the twentieth century, not the new and shiny one that they are bragging over.

And if one is loose and the other is tight, there will be a small electric arc sparking. (Which leads to ...)
High Voltage socket-nose-avatar

Re: Power cord blind test

Reply #12
"dirty" could be "corroded".
Which is what I said in my first post.

It's often enough to simply plug the cable in and out a couple times to rub off any corrosion or dirt.


Re: Power cord blind test

Reply #14
I fail to see why this test should be given any credibility.  The assumption that the result is legitamite combined with the pretzel twisting is pretty comical though.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Re: Power cord blind test

Reply #15
I fail to see why this test should be given any credibility.  The assumption that the result is legitamite combined with the pretzel twisting is pretty comical though.

The first video seems to have been faked as there was a channel imbalance. The second video, no channel imbalance but the test seems to be contaminated with expectation/confirmation bias. The reviewer even labels A as the freebie cable and B as the expensive power cord so it's not really a test.

 
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