To tweak or not to tweak. That is the question! For some, or rather for the growing crowd of audiophiles and music lovers, this is the question that with the rise of high-end audio accessories, is becoming more and more feasible. 

Some will never want to explore any tweaks or options to increase performance in their system, but for those who are interested, there are many interesting and growing high-end audio paraphernalia on the market. 

In most cases, these products are theories that deal with the application of principles and ideas that operate on the borderline of fringe science, to say the least, or go well beyond the unknown realms. But in the sheer vastness of these devices, there are always a few gems that actually work and introduce certain positive attributes to the overall performance of a high-end audio system.

As our readers become more and more interested in fine-tuning their beloved high-end audio systems on all fronts, when offered, I was happy to oblige by exploring the latest Furutech addition to the expanding line of effective NCF products. 

NCF Clear Line is an AC audio-quality optimizer that’s small enough to hold in your hand and designed from the ground up for instant quality improvement.

As you can read throughout the review the newly gained attributes are not exactly marginal. 

There’s a lot to appreciate about the Furutech NCF Clear Line AC Optimizer in terms of features, materials, and unique technologies, so let’s take a look at those first.


Furutech’s Nano Crystal² Formula, also known as NCF, has resulted in several truly innovative and effective products in recent years. NCF contains a special crystalline material that has two distinct properties – it generates negative ions that eliminate static, and it converts thermal energy into far-infrared. 

When combined with nanoscale ceramic particles and carbon powder, these crystals become the terminal electrical and mechanical damping material. NCF was developed by Furutech and is found exclusively in Furutech products and nowhere else.

Now Furutech has introduced perhaps the easiest way to use NCF technology in domestic audio systems – NCF Clear Line.

NCF Clear Line is a passive AC audio grade optimizer that is small enough to hold in hand and instantly improves the quality of the power supply.  The NCF Clear Line is simply plugged into any available receptacle on a power distribution board or wall outlet. For best results, it’s recommended to use the NCF Clear Line on the same AC line/supply as a high-end audio system, preferably on an outlet next to the system. 

The NCF built into select Furutech products is made of a special crystalline material that has two “active” properties. First, it forms negative ions that eliminate static. Second, it transforms thermal energy into far-infrared. 

Furutech couples this remarkable material with nano-sized ceramic particles and carbon powder for their additional damping properties through the ‘piezoelectric effect’. 

The resulting Nano Crystal² Formula is the ultimate electrical and mechanical damping material. It was developed by Furutech and is found exclusively in Furutech products.


Using state-of-the-art technologies and materials, Furutech has developed a two-stage, low-temperature process that significantly improves every facet of audio performance. 

The treatment begins during the manufacturing process with a deep, conditioning cryogenic freeze of all metal parts. Using high-end refrigerants – liquid N2 or He – Furutech achieves temperatures from -196 to -250℃. At these extreme temperatures, the treated parts change their molecular structure, relieving internal stresses. The molecules bond more tightly together and the overall structure becomes more stable. This improves electrical conductivity and thus power and signal transmission.

In the second step, the same parts are subjected to the patented ring demagnetization treatment at Alpha Process. Ordinary high-power magnets used for this purpose often amplify the magnetic effects; leaving some areas more magnetized than others. This patented process uses controlled damping to entirely eliminate magnetization, making sound quality more vibrant and colorful. Ring demagnetization further improves the conductivity of all treated materials.

All metal parts used in Furutech products go through the Alpha Process treatment to keep all connectors, conductors, and metal parts in a perfect, stress-free, stable, and highly conductive condition.


The body of the NCF Clear Line is made of nylon and glass fibers, incorporating nano-sized ceramic particles and carbon powder for their added “piezo effect” damping properties. Furutech’s NCF (Nano Crystal2 Formula) eliminates static, “interconverts” thermal, mechanical, and electrical energy and dampens vibration.
Furutech’s NCF Clear Line uses enameled α (Alpha)-OCC Air Coil passive wire coils with proportional inductance and current magnitudes to improve the system’s current quality and sonic performance. 
Each α(Alpha)-OCC Air Coil in the NCF Clear Line is designed to complement the performance-enhancing properties of Furutech’s unique NCF (Nano Crystal Formula) anti-static and resonance-damping material.
The material and design of each α(Alpha)- OCC Air Coil were determined after countless tests, using coil winding length to tune the sonic performance of the device. 
As result, Furutech’s NCF Clear Line eliminates noise, removes static, and improves the overall quality of performance, taking the high-end audio system’s performance to the next level.

The NCF Clear Line body and housing are secured with special tamper-resistant T10 stainless steel screws and washers. Factory tightened to the optimum torque value for best sonic performance.

The NCF Clear Line case liner ring is molded from special resonance dampening nylon and Furutech’s NCF material, and the barrel case is constructed from 4 layers of Furutech’s hybrid NCF carbon fiber.

  1. Outer layer – Special hardened clear coating
  2. NCF & special texture Carbon Fiber particle composite
  3. NCF & 3K Carbon Fiber
  4. Inner layer – NCF Nylon resin insulation
  5. The internal air chamber is pressure sealed to for additional damping effects

The NCF end cover is made of special heat-resistant nylon and Furutech ‘s NCF material molded with shaped channels to increase the surface area of the NCF material by 76% for improved effectiveness – ultimate resonance damping for improved tonal balance.


1. The special T10 tamper-proof stainless steel self-tapping screws and washers

2. NCF (multi-material hybrid structure): NCF formulated nylon resin (Body). α (Alpha) Pure-Copper Rhodium-plated Conductor

3. Coils: α (Alpha)-OCC conductor enameled wire; outer layer coated with polyurethane western paint, and then sprayed with a special acrylic paint.

4. NCF (multi-material hybrid structure) insulation plate: Anti-static and resonance suppressing qualities.

5. Housing: NCF formulated nylon resin and special texture carbon fiber housing, incorporating a special nylon resin insulation ring. The best of damping and insulation materials improve frequency extension and tonal balance.


The NCF Clear Line needs to be plugged into any available outlet on a power distributor, power ladder, or wall outlet. For best results, the NCF Clear Line should be used the same AC line/supply as the audio system, preferably on an outlet next to the system. 
In a reasonable well-tuned and balanced high-end audio system, it should only take a bit to hear the improvement in sound. There is no A/B test needed to discern the improvement.
But, when the NCF Clear Line is removed from the AC outlet, the shift is immediate.
Newly gained sonic depth, pin-point accuracy, better low register foundation, overall clarity, and grander dynamism are instantly missed.


Anders Aarum Trio’s album Absence In Mind is a tour de force in itself with a plethora of hidden musical and sonic little delights. The multiplex layering of piano, double bass, and drums creates a unique soundscape that can all too quickly become too chaotic to follow. With the NCF Clear Line AC Optimizer in action, everything somehow became more focused, with a clear perspective and enhanced fundamentals. All instruments hold their allotted space much better. 

The avant-garde aural kaleidoscope was simply converted more lucid and clear. 

The dark mood of Dhafer Yussef Abu Nawas Rhapsody is another challenging album. Particularly on the track “Sacre,” I noticed a noticeable boost in the lower registers, which the Furutech NCF Clear Line AC Optimizer pushed the positive qualities further than expected. Something was happening in the second and odd harmonic range that just felt more right and involving. Not exactly the attribute I would associate with such a device as an AC optimizer! 

With Furutech NCF Clear Line AC Optimizer Squad Massi ‘ “Denya Wezmen” from That’s Life, again the positive effects were not marginal. AC Optimizer let the music unfold with a bit more intensity. It also took away the edges of sibilants a bit, making them more real.

The sheer force of the dynamics is already on its level with Kari Ikonen Impressions, Improvisations, and Compositions. Especially with “Maqtu’ah on Maqam Rast” the Furutech NCF Clear Line AC Optimizer clearly explicated its advantages. There was a clearer overall definition of detail, with what I would sware a half a virtual dB of gain added. The uncluttered dynamic progression of the piano was immediately noticed, as was the 3D holographic expansion. The rhythm of “Maqtu’ah at Maqam Rast” was tighter, the sense of space extended, filling the room with more tangible weight. There was that little scent of flour (in terms of believability) that put the icing on the cake. 

Patsy Cline – Patsy Cline’s Greatest Hits “Crazy” can sound quite sharp and brittle. When the quality of the electricity fluctuates, you can immediately recognize the mains power hubris in action. 

In an unbalanced system, Cline’s vocals are easily pushed into the brittle realms, making them instantly unlistenable. Interestingly, the NCF Clear Line AC optimizer somehow smoothed out the edges of this particular harshness without taking out the harmonic content or making Cline sound inarticulate and aphasic.


Although the Furutech NCF Clear Line AC Optimizer appears to be a simple, passive device, it proved to be David against Goliath in terms of what it can do in the different areas. 

The multi-material hybrid design with a carbon fiber enclosure (shell) with excellent resonance damping properties allows music to be more transparent and less fatiguing. 

The Furutech NCF Clear Line AC Optimizer took a good day and a half to stabilize in its new role when plugged in the Nordost QB8. 

After settling in, the multiple qualities like higher resolution, lower noise floor, better 3D and far denser holography, more focused lower register and more locked bass, texture, vibrancy and sharper, more lifelike attacks, and leading edges of notes, were discerned. Yes, quite a positive set of attributes. 

The sheer complexity of this rather simple-seeming device has already been explained at length. There is no doubt that a lot of research and development went into the housing and product itself.

With the NCF Clear Line AC Optimizer, beauty is not in the eye of the beholder. The quality is immediately apparent, but only upon closer inspection. The unique surface appearance of the carbon fiber shell doesn’t show in photos. It is only visible to the naked eye. Those who have been following me for a while know that I have a soft spot for carbon fiber as a material for a variety of reasons and this Furutech device is a beautiful representation of handling the material right, which is not always the case.

The entire enclosure (shell) was composed for optimal enforcement of NCF damping, and while the exterior may be uncommon, the effect on playback performance is outstanding. The frame was envisioned as a hybrid blend of an outer hardcover over an NCF textured carbon fiber particle composite layer. And beneath is a layer of NCF and a 3K carbon fiber layer.

As mentioned in the music references, it only takes a few notes to realize the benefits of Furutech’s NCF Clear Line. Often marketing blurb claims and promises grander performance, but fails in reality. Not so with this Furutech high-end audio gizmo.

The Furutech NCF Clear Line AC Optimizer may not be the cheapest high-end audio accessory, but it’s not the most expensive either. And for what it can do on multiple levels and in multiple assignments, it’s more than worth recognizing. 

For what it represents, I grant the Furutech NCF Clear Line AC Optimizer 2021 Mono and Stereo Best Buy Product Award. 

The stream of Furutech novelties is in a more than healthy perpetual motion. I’m sure the Furutech team is already working on several more than interesting products. So stay tuned!. 

Matej Isak


  • MSRP: $250 USD


  • Outward size: L 88.4 X W39.5 mm approx.
  • Net Weight: 69 g approx.
  • Suggested burn in time 24 hrs.



Furutech Bldg.

3-9-1 Togoshi


Tokyo 142-0041


Tel: +81-(0)3-6451-3941

Web: www.furutech.com