Furutech FI-C15 (G)

The Furutech FI-C15(G) is an IEC connector designed for amplifiers with hard-to-reach sockets. Its slim profile lets you install it where standard models won’t fit. It uses a 24k gold-plated α pure copper conductor and a glass fiber–reinforced nylon body to ensure strength and resonance control, while retaining Furutech’s proprietary metallurgical treatments.

A slim body for tight installations

Amplifier designers don’t always make life easy: IEC inlets tucked against heat sinks, tight spacing between connectors, close to switches or vents. The FI-C15(G) was developed with owners of LINN, Devialet, McIntosh amplifiers and other devices in mind, where the rear panel looks more like a puzzle than a rational connection zone.

Its dimensions speak for themselves: 22 mm wide by 30 mm high, a notable reduction compared to traditional IEC connectors that often measure 28 to 35 mm wide. This compactness isn’t limited to the exterior footprint. The internal geometry has been reworked to maintain effective conductor clamping while keeping a slim body. The set-screw clamping system secures cables up to 16 mm in diameter, a compatibility that covers most current high-end power cables.

The two-part assembly—main body and internal cover plate—greatly simplifies installation. Where some connectors demand contortions and watchmaker-level patience, the FI-C15(G) opens wide to give access to the terminals. The three connection screws (two poles plus ground) are color-coded, a detail that prevents unfortunate reversals during wiring.

Alpha pure copper and the choice of gold plating

The FI-C15(G) conductor is made from α (Alpha) pure copper, a designation for the material after undergoing Furutech’s proprietary treatment. This two-step process alters the metal’s molecular structure to improve conductivity. The 24k gold plating that coats this conductor isn’t just about aesthetics or oxidation resistance.

Gold imparts a specific sonic signature, well documented in technical literature and listening comparisons. Compared to rhodium—the other plating option Furutech offers on different models—gold brings more body to the midrange, a certain roundness to timbre, and a less analytical presentation. Rhodium favors transparency, spatial definition, and a more pronounced treble extension, but can sometimes lay bare imperfections in the system or the power grid.

Gold plating is particularly suitable for systems that lean toward precision and would benefit from a bit more density and warmth. It also pairs well with power cables that are neutral or slightly dry in character. Conversely, a system that’s already warm might find better balance with the rhodium version (FI-C15 NCF(R)). This question of synergy explains why Furutech consistently offers its connectors in multiple plating finishes.

Gold’s corrosion resistance remains superior to bare copper or nickel-plated brass. Over time, the connection maintains its quality without oxide formation that would increase contact impedance. One technical detail deserves attention: phosphor bronze, sometimes used in entry-level connectors, has good mechanical properties but lower conductivity than pure copper. Furutech makes the opposite choice by prioritizing material purity.

The Alpha Process treatment: cryogenics and demagnetization

Since its founding in 1988, Furutech has built a reputation on a simple principle: every link in the electrical chain matters, including—and perhaps especially—the mains power supply. In the 2000s, as Furukawa Electric ceased production of its PCOCC cables (Ohno Continuous Cast single-crystal copper), Furutech introduced its own metallurgical treatment called the Alpha Process.

This two-step process begins with deep cryogenics. Metal parts are cooled between -196°C and -250°C using high-purity refrigerants (liquid nitrogen or helium). At these extreme temperatures, the metal’s molecular structure reorganizes. Internal stresses from manufacturing and machining are relieved. Molecules bond more tightly and the whole becomes more stable. This modification improves electrical conductivity and, by extension, power and signal transfer.

The second step uses a patented ring-demagnetization treatment developed by Sekiguchi Machine Sales and licensed to Furutech. Conventional high-power magnets often create more problems than they solve: they leave unevenly magnetized areas. The controlled attenuation process eliminates residual magnetization entirely. The effect on the soundstage is immediate, with greater depth and clarity.

This Alpha Process treatment is applied to all metallic components of Furutech products, from conductors to clamping screws. The goal is to keep each part in an optimal state: stress-free, stable, and highly conductive. The process represents a significant investment in time and equipment, but Furutech applies it even to its mid-range products, including the FI-C15(G).

Technical Specifications

Materials and Construction

• Conductor: Alpha pure copper with 24-karat gold plating
• Body: Nylon/fiberglass for the main body and inner plate
• Clamping system: Polycarbonate with stainless steel screws

Compatibility and Dimensions

• Compatible cable diameter: 6.6 mm to 16.0 mm
  • Maximum cross-section: 3.5 mm² / 12 AWG
• Connector dimensions: 22.0 mm × 30.0 mm × 82.2 mm
  • Total length: 82.2 mm

Connection System

• Connection type: Screw clamp

Design Features

• Slim, compact design for easier access to hard-to-reach IEC sockets
• Warm, smooth, and musical sound reproduction thanks to 24-karat gold plating
• Robust, anti-resonance structure
• Compatible with audiophile cables up to 16 mm in diameter

Recommended Applications

• High-end amplifiers and audio devices with IEC sockets in restricted-access areas
• Demanding audiophile systems requiring a reliable, stable connection
• Compatible equipment: LINN, Devialet, McIntosh amplifiers, and similar devices

General Information

The Furutech FI-C15(G) is a high-performance IEC connector specifically designed for compact, demanding audiophile setups. Its slim design allows for easy installation in tight spaces, ensuring an optimal connection for the most sophisticated audio systems. The 24-karat gold plating on the Alpha pure copper conductor delivers a sonic signature that emphasizes musicality and expressiveness, ideal for audiophiles seeking a natural, engaging sound.