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Furutech NCF Clear Line Review (AC Optimizer)

Rate this product:

  • 1. Waste of money (piggy bank panther)

    Votes: 250 96.5%
  • 2. Not terrible (postman panther)

    Votes: 1 0.4%
  • 3. Fine (happy panther)

    Votes: 1 0.4%
  • 4. Great (golfing panther)

    Votes: 7 2.7%

  • Total voters
    259

amirm

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This is a review and detailed measurements of the Furutech NCF Clear Line "AC Power Supply Optimizer." I bought it for US $236 from Amazon seller.
Furutech NCF Clear Line AC Optimizer Review.jpg

I expected the device to be the typical AC mains filter but this is not so based on my reading. Company has this interesting notation in its advertising:
Furutech NCF Clear Line AC Optimizer Review No circuit passive N L.png


It seems to be saying that there is nothing between Neutral and Line (Hot) terminals! What is there then? They have a short video that shows the following:
Furutech NCF Clear Line AC Optimizer Design.png


There are two air core coils with one lead attached to its corresponding mains terminal. But the other side from what I can tell is just connected to the enclosure of the device itself (???). Here is a more clear shot:
Furutech NCF Clear Line AC Optimizer Design Air Coil.png


Company claims reduction in noise and indeed we read that in a couple of reviews they have posted on product page:

Furutech NCF Clear Line AC Optimizer Review Comment.png


Furutech NCF Clear Line AC Optimizer Review 2 SNR noise Comment.png


We can easily measure SNR and noise so it is nice to see that as a point of verification.

I looked everywhere to see if there is any safety regulatory certification and sadly, there is none. No UL. No CE. No CSA. No ETL. Nothing. If the design does tie the hot lead to the case of the device, I would be seriously worried about lack of such certification.

Furutech NCF Clear Line Measurements
I started first by attempting to determine if there is a circuit between the terminals. I could not measure either resistance or inductance between any of the three plug terminals. Using a capacitor meter, I measured just 2 picofarad between hot and neutral which is basically nothing. So it seems my interpretation above is correct: there is no circuit at all between any of the terminals. We could stop here and be done but let's do our usual measurements.

We start with usual measurement of my AC mains, this time with 1 MHz bandwidth given the claims of "high frequency noise:"
Raw AC Noise and Distortion Measurement.png


As usual, my AC power strip provides fairly distorted and noisy AC waveform. I then plugged in the Clear Line in the same power strip and got this:

Raw AC Noise and Distortion with Furutech NCF Clear Line Filter Measurement.png


Nothing is changed whatsoever. Even that little glitch in the AC waveform is allowed to pass through unchanged. Let's look at the spectrum of the noise/distortion for better insight:
Raw AC Noise and Distortion with Furutech NCF Clear Line Filter FFT Measurement.png


Same outcome.

Next, I ran the Audio Precision APx555 analyzer in its loopback mode to see if the device increases its signal to noise ratio:
Furutech NCF Clear Line Measurements APx555 SNR Noise measurement.png


It does not. Looking at the spectrum of noise, again with 1 MHz bandwidth we get the same outcome:

Furutech NCF Clear Line Measurements APx555 FFT SNR Noise measurement.png


We could keep testing but seeing how there is no impact on the AC power itself, there can't be any in audio device which further filters that input.

NCF Clear Line Listening Tests
I used my everyday setup for listening test: RME ADI-2 DAC powering my Dan Clark Stealth headphone. The Stealth is closed back so nicely isolates the headphone from room noise. I played through my reference tracks while connecting and disconnecting the NCF Clear Line. There was absolutely no difference. This is an easy test because the sound keeps playing so there is no glitch to disturb the testing, or make you forget how something sounded.

Conclusions
Many of the AC filters I have tested have some kind of electrical filter so they do "something." The Clear Line has none according to its manufacturer and my testing. So no wonder that it has no impact on AC signal. And with that waveform unchanged, even if you plugged in a poorly designed audio device, you would not get a difference. How someone can have such a misguided idea that hooking up a few turns of a wire between a terminal and insulator of the plug does some good, is beyond me.

The "nice" thing here is that a blind AB test is trivial to setup. Levels will not need matching and connection/disconnection has no glitch/impact. So anyone who says the sound is improved is highly encouraged to perform such a test and post a video of it.

Needless to say, I cannot in any form or fashion recommend the Furutech NCF Clear Line.

Edit: video review also posted:


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digicidal

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So you could replicate this device perfectly by simply shoving two lengths of wire into your outlet and making sure they don't touch each other... seems legit.
 

respice finem

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Might be "interesting" for lawyers I guess. Stating anything subjective is one thing, but stating parameters that are not met is another (SNR).

Ceterum censeo: caveat emptor.
 

DSJR

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You can send it back for a refund, yes? Hell of a lot of dough to lose if not :(
 
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JSmith

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The Germans still practice this evildoing :facepalm:
Still happens here in Aus too. If it's one of the major banks there is no per transaction charge, but if it's a 3rd party company ATM (which most in bars etc. are) then it's a $2.50 charge... I refuse to use them unless I have no choice at the time.
You can send it back for a refund, yes?
For sure, I would be... not fit for purpose!


JSmith
 

StuartC

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Still happens here in Aus too. If it's one of the major banks there is no per transaction charge, but if it's a 3rd party company ATM (which most in bars etc. are) then it's a $2.50 charge... I refuse to use them unless I have no choice at the time.

For sure, I would be... not fit for purpose!


JSmith
Ditto the UK
 

Jimbob54

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For anyone posting on this forum around " what is snake oil? " "What is the difference between snake oil and a rip off?" and similar , point them here. This product is both snake oil (it clearly does nothing but makes claims to do something) AND a rip off- as they gouge you for $200 of nothing. Awful.
 

respice finem

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For anyone posting on this forum around " what is snake oil? " "What is the difference between snake oil and a rip off?" and similar , point them here. This product is both snake oil (it clearly does nothing but makes claims to do something) AND a rip off- as they gouge you for $200 of nothing. Awful.
What makes it even worse, for this much, one might buy something that really works a bit...
 

voodooless

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... But did you listen to it...? It says it right there on the product page:

It only takes a moment to hear the improvement in the sound.

And obviously, you forgot to burn-in :facepalm:
  • Suggested burn-in time 24 hrs

And it even works for video:
1651481421324.png


... incredible ...
 
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