Furutech Clear-Line NCF USB

Furutech NCF Clear Line-USB: addressing noise on the USB port

A USB port carries both data and power voltage, and this dual function makes it an entry point for electromagnetic noise circulating within a digital system. Furutech addresses this specific issue with a small passive plug to insert into an unused USB socket. No power supply, no driver, no adjustment: insert it and it acts on the port that receives it.

A passive plug in an unused USB socket

Furutech offers its Clear Line range by socket type. The first version, released in 2020, fitted into a mains socket; two RCA and XLR models followed in 2023 for analogue connections; the USB and LAN versions arrived in 2024. The NCF Clear Line-USB fills the digital slot in the catalogue, on the USB-A port of a digital-to-analogue converter, a network player, an audio-video receiver or a preamplifier.

The principle remains the same from one model to another: a fully passive enclosure, without power supply or software, inserted into an unused socket. Passive does not mean empty. The optimiser contains electrolytic capacitors and metal shielding, but no active stage and no power requirement. Plug it in, and it works on the port that receives it.

Damping resonances and shielding the connector

The USB connector is 24-carat gold-plated on a non-magnetic base. Furutech incorporates gold-plated copper-alloy anti-interference shielding, designed to limit electromagnetic noise around the socket and stabilise the connection.

Inside, electrolytic capacitors selected by the brand feature a silver-coloured damping coating that reduces vibrations. The body combines several materials chosen for their damping properties: a stainless-steel retaining ring combined with Furutech’s in-house NCF, a four-layer forged-texture carbon-fibre shell blended with NCF, and a heat-resistant nylon cover also loaded with NCF. A sealed internal air chamber under pressure adds further damping.

NCF, or Nano Crystal² Formula, is Furutech’s signature material: a crystalline compound that damps mechanical resonances and dissipates static charges. The assembly is closed with stainless-steel security screws factory-set to a precise torque, and is not designed to be dismantled.

Alpha treatment for metal parts

All metal parts undergo the Alpha process, a two-stage treatment. First comes deep freezing: the metals are immersed in liquid nitrogen or helium, between -196 and -250 °C. At this temperature, the molecular structure reorganises, internal stresses are relieved and the material gains stability, resulting in improved electrical conductivity. This is followed by ring demagnetisation, a patented process that removes residual magnetisation left by manufacturing rather than increasing it. Furutech applies this same preparation to all of its conductors and connectors.

Where to insert it, and what a treated port can achieve

Installation takes just one movement: identify an unused USB-A port on the source or preamplifier, then insert the optimiser. Nothing passes through it; it does not add a port or relay any signal. It occupies an unused socket and acts on the interface. Furutech recommends a burn-in period of at least 24 hours before critical listening.

This raises the fundamental question. A USB port carries a digital signal and a 5-volt line, and it is on the high-frequency noise and interference of this interface that the optimiser seeks to act, lowering the noise floor and improving the signal-to-noise ratio. The extent of the result depends on the rest of the system, the quality of the existing power supply and individual sensitivity. This type of accessory is a fine-tuning adjustment, best assessed on your own system rather than by a numerical claim. The process is reversible and risk-free for the equipment, making it an easy addition to test before deciding whether to keep it.

Technical Specifications

Overview

• Model: NCF Clear Line-USB “USB Optimizer” (1 piece)
• Function: USB port optimizer to be plugged directly into an available port
• Audio benefits:
  • Significant improvement in signal-to-noise ratio (S / N)
  • Increased level of detail and faithful reproduction of subtle nuances
  • Coloration-free reproduction, preserving the original character of the source

Connector Technology

• Non-magnetic 24-karat gold-plated USB connectors
• Integrated EMI shielding in specially designed 24-karat gold-plated copper alloy
• Benefits:
  • More stable, clearer and more precise audio transmission
  • Excellent conductivity ensuring audio signal stability and consistency
  • Reduction of electromagnetic interference from the environment

Internal Components

• Electrolytic capacitor:
  • Type and specifications selected after extensive testing to optimize acoustic performance
  • Outer layer coated with a high-performance silver-colored special damping treatment, effectively suppressing unwanted vibrations
  • Advanced tuning technology eliminating noise interference from equipment output terminals
• Semi-sealed air chamber: pressurized internal chamber providing an additional damping effect

Construction and Materials

• Housing body ring: special anti-resonance stainless steel combined with Furutech NCF material
• Housing: 4-layer special hybrid carbon fiber construction with forged NCF texture
• NCF end cap: special heat-resistant nylon combined with NCF material for optimal resonance damping and improved tonal balance
• Fastening: custom shock-resistant stainless steel security screws, factory-set to optimal torque
• Structural benefits: improved frequency extension, optimized tonal balance, superior damping and isolation

Alpha Process: Two-Step Cryogenic Treatment and Demagnetization

• Treatment applied to all metal parts of Furutech products
• Step 1 — Cryogenic treatment:
  • Use of high-grade refrigerants: liquid nitrogen (N2) or helium (He)
  • Temperatures reached between -196 and -250 ℃
  • Modification of the molecular structure, releasing internal stresses
  • Strengthened molecular bonds and a more stable overall structure
  • Improved electrical conductivity and power and signal transfer
• Step 2 — Patented ring demagnetization:
  • Controlled attenuation completely eliminating residual magnetization
  • Elimination of unevenly magnetized areas left by conventional magnets
  • Further improvement in the conductivity of treated materials
  • Result: more vivid and colorful sound imaging

Use

• Plug and play installation: insert the NCF Clear Line-USB into an available USB port on the equipment
• Recommended locations for optimal results:
  • System preamplifier
  • Audio / video amplifier (AV receiver)
  • Digital-to-analog converter (DAC)
  • Streaming player
• Immediate audible effects:
  • Improved depth and focus of the soundstage
  • Optimization of harmonics and sound balance
  • Increased transparency and reduced high-frequency noise
  • Enhanced overall contrast, reduced distortion, increased clarity

Recommendations and Notes

• Recommended break-in period: 24 hours or more
• Product screws are fixed: do not disassemble or modify yourself
• The carbon fiber pattern of the housing varies from product to product: it is formed from the carbon damping composite material and serves only to enhance the listening experience
• Some parts use non-magnetic stainless steel; slight magnetism may nevertheless occur due to manufacturing stresses, without affecting performance