Furutech Clear-Line NCF LAN

Furutech Clear-Line NCF LAN, the network port noise filter

A dematerialized audio stream never arrives alone through the Ethernet port of a streamer or DAC: electrical noise from the home network travels with it, including the router and switching power supplies. Furutech extends its Clear Line range, launched in 2020 for mains power and then expanded to analogue connections, with a version that fits into an unused RJ45 port to absorb some of this interference. Passive and requiring no adjustment, it simply needs an available connector.

An accessory that occupies an unused port

The Clear-Line NCF LAN plugs into an unused Ethernet socket on the device of your choice: network player, DAC, preamplifier, home theater amplifier, as well as a switch, router, access point or NAS server. It does not replace the network cable and is not inserted into the connection carrying the data. It remains in parallel, on a free port, and works on the noise present at this interface rather than on the useful signal. Once plugged in, it operates without intervention.

This shunt operation distinguishes it from a filter inserted in series with the connection, which breaks the ground loop or reclocks the signal. Here, the action targets high-frequency interference coming in through the connector, and its benefit depends both on the amount of noise actually present and on the refinement of the rest of the system.

Shielding and capacitor housed in the plug

Inside the RJ45 connector, a 24-karat gold-plated copper-alloy interference shield surrounds the contacts, which are themselves gold-plated and non-magnetic. Gold offers good conductivity and highly stable contact; the aim is to limit the electromagnetic noise picked up at this point.

An electrolytic capacitor completes the assembly. Its outer layer receives a silver-coloured vibration-damping treatment, and its tuning is designed to drain away interference returning via the device’s output terminals. This component gives the housing its larger volume compared with a simple protective plug.

NCF materials and the carbon-fiber shell

The body combines several damping materials. The structural ring pairs damping stainless steel with the in-house NCF (Nano Crystal² Formula) material, a compound loaded with ceramic nanoparticles and carbon powder that dissipates static charges and reduces mechanical resonances. The shell layers four sheets of forged carbon fiber blended with NCF, while the rear cap combines heat-resistant nylon with the same material.

An internal air chamber, pressure-sealed, adds a damping effect. The assembly is closed with stainless-steel security screws factory-set to the required torque: the housing is not designed to be opened, and these screws cannot be removed.

Cryogenic and demagnetization treatment

All metal parts undergo Furutech’s Alpha process, in two stages. The first immerses the metals in extreme cold, between -196 and -250 °C using liquid nitrogen or helium: the molecular structure reorganizes, internal stresses are relieved and conductivity improves. The second subjects these same parts to demagnetization using a controlled attenuation ring, which erases magnetized zones rather than creating new ones. The treatment applies to all connectors and metal parts to keep them in a stable, conductive state.

Burn-in and precautions to know

The effect is apparent as soon as it is connected, then stabilizes: it is best to leave the Clear-Line NCF LAN in place for at least twenty-four hours before critical listening. The carbon-fiber pattern varies from one unit to another, a result of the composite material and with no effect on operation. The stainless steel used is non-magnetic, but some parts may show slight residual magnetism related to manufacturing stresses, with no effect on performance. The product is sold individually, allowing installation on several ports or several devices.

Technical Specifications

Overview

• Model: NCF Clear Line-LAN “LAN Optimizer” (1 piece)
• Principle: LAN optimizer to be plugged in directly for immediate improvement of the signal-to-noise ratio (S/N)
• Benefits: enhanced detail retrieval, better reproduction of subtle nuances, without coloration of the source signal

Connector Technology

• 24k gold-plated, non-magnetic LAN connectors
• 24k gold-plated copper alloy electromagnetic interference (EMI) shielding, specially designed and integrated into the LAN connector
  • More stable, clearer and more precise audio transmission
  • Excellent gold conductivity ensuring audio signal stability and consistency
  • Reduction of electromagnetic interference from the environment

Electrolytic Capacitor

• Electrolytic capacitors selected after extensive testing to optimize acoustic performance
• High-performance silver outer coating with special damping treatment that suppresses unwanted vibrations and enhances sonic clarity
• Advanced tuning technology eliminating stray interference from the equipment’s output terminals

Furutech Two-Step Alpha Process: Cryogenic Treatment and Demagnetization

• Step 1 — Deep cryogenic treatment of all metal parts
  • High-grade refrigerants: liquid nitrogen (N₂) or liquid helium (He)
  • Temperatures reached: from -196 °C to -250 °C
  • Modification of the molecular structure, release of internal stresses, enhanced molecular cohesion
  • Improved electrical conductivity as well as power and signal transfer
• Step 2 — Patented Ring Demagnetization treatment
  • Controlled attenuation to completely eliminate residual magnetization
  • More lively and colorful sound and image reproduction
  • Increased conductivity of all treated materials
• Application: all metal parts in Furutech products undergo the Alpha process to maintain connectors, conductors and metal components in a stable, stress-free and highly conductive state

Construction and Materials

• Semi-sealed air chamber
  • Pressurized sealed internal chamber providing an additional damping effect
• Housing body ring made of resonance-damping stainless steel and Furutech NCF material
• Housing constructed from 4 layers of special hybrid carbon fiber with forged NCF texture
  • Damping and insulation materials optimizing frequency extension and tonal balance
• NCF end cap made of special heat-resistant nylon combined with Furutech NCF material
  • Ultimate resonance damping for improved tonal balance
• Main body and shell secured with custom shock-resistant stainless steel security screws
  • Tightening torque factory-set for optimal performance
  • Non-removable screws, not to be modified by the user

Use

• Installation: simply insert the NCF Clear Line-LAN into an available LAN port on the equipment
• Recommended locations for optimal results: available LAN ports on the preamplifier, AV amplifier, DAC or streaming player
• Immediate audible improvements:
  • Increased depth and focus of the soundstage
  • Better reproduction of harmonics and tonal balance
  • Enhanced transparency and reduced high-frequency noise
  • Improved overall contrast, reduced distortion, increased clarity

Notes

• The product screws are fixed: do not disassemble or modify them yourself
• Recommended break-in time: 24 hours or more
• The carbon fiber pattern of the shell varies from product to product; it is made from a carbon damping composite material and has only a beneficial effect on listening
• Furutech uses non-magnetic stainless steel for certain parts; slight magnetization may occur due to manufacturing stresses, without affecting performance