Inakustik Reference NF-1205 AIR | RCA 1m

An interconnect cable creates nothing; it loses. The entire challenge is to lose as little as possible between a source and an amplifier. in-akustik addresses the issue through subtraction: removing plastic insulation, removing solder, removing anything that stores energy along the way. The fifth generation of its AIR technology takes this reasoning down to the very last centimeters, inside the plugs themselves.

Air as insulation, and almost nothing else

The capacitance of an interconnect cable matters more than in a speaker connection, because the signals traveling between two devices are weak and sensitive to the load imposed by the line. Conventional plastic insulation stores some of this energy and releases it with a slight delay. Air, on the other hand, adds no extra capacitance and generates no dielectric losses.

The challenge is to keep the conductors apart without placing anything between them. in-akustik uses clips spaced at regular intervals along the entire length, holding the conductors in a helical arrangement and suspending them in open air. Two spacers connect the clips and set their separation, preserving a degree of flexibility despite the assembly’s apparent rigidity. The jacket follows the same logic: no PVC, but a braid of polyethylene monofilaments that grips the conductors, limits micro-vibrations and adds no insulating material around the signal. The final diameter reaches 13 mm, a direct consequence of this design.

Fifth-generation point-to-point construction

In previous generations, the air helix stopped before the ends: the conductors left their clip structure to reach the plugs over the final centimeters, reverting to conventional insulation in the process. The fifth generation, which replaces the NF-1204 AIR, eliminates this break with transitions designed for each type of cable and connector. Air insulation now runs from one plug to the other.

The difference concerns only a few centimeters, which may seem anecdotal. Yet this is the area where material density is highest and where the conductor comes closest to the connector’s metal masses.

A braided conductor against skin effect

The conductor is called the Cross Link Super Speed waveguide. It is based on a polyethylene core around which the strands are braided in a ring, with an effective cross-section that remains constant regardless of frequency. Each strand receives a varnish coating that insulates it from its neighbors and protects it against oxidation. The copper is high-purity OFC, selected in batches before drawing.

The stated argument is combating skin effect, the phenomenon that pushes current toward the conductor’s outer surface as frequency rises. In an audio-frequency interconnect cable, this effect remains modest compared with its significance at radio frequencies. The braided structure mainly provides homogeneous conduction and good handling of current peaks, without particularly emphasizing any part of the spectrum.

Two separate cables, one per channel

The construction is coaxial, with double-mono technology: the two channels share no conductor, each having its own complete cable. The higher models in the range, NF-2405 AIR (25 mm) and NF-4005 AIR (40 mm), use a balanced design and take up significantly more space.

An RCA connection remains inherently unbalanced, making it dependent on the quality of its shielding to reject interference. Here, in-akustik uses a dense copper braid, tin-plated against oxidation. Electromagnetic interference produced by Wi-Fi networks and mobile phones has increased significantly in recent years, and a low-level analog connection is directly exposed to it.

RCA plugs assembled without solder

The RCA SL plug was developed for this cable and does away with tin entirely. The varnish is first machine-stripped from the copper strands, then the tellurium copper contact pin is crimped into the conductor under a pressure of 1.5 tonnes. The shield connection is made by airtight screw fastening. There is therefore no solder or intermediate crimp ferrule remaining in the signal path, reducing transition resistances accordingly. The trade-off is logical: a press-crimped termination cannot be redone at home; changing a plug requires workshop service.

Tellurium copper is a harder alloy than pure copper, which is too soft for a connector, while retaining conductivity superior to brass. The plating is rhodium rather than gold: gold conducts better, but wears more quickly on a frequently handled contact, whereas rhodium withstands repeated connection cycles without deteriorating.

Assembly is carried out by hand in Ballrechten-Dottingen, Germany. The manufacturer counted the parts in a 1.5 m pair: 254 components, 855 m of copper wire, 334 m of polyethylene monofilament and 208 holes through which the conductors must be threaded one by one.

What to plan for during installation

Thirteen millimeters in diameter and a firm jacket require space behind the furniture. It is best to check the available depth before ordering, allow for a generous bend radius and avoid placing the full weight of the cable on the RCA sockets of a lightweight device. Three lengths are listed in the catalog—1 m, 1.5 m and 2 m—with custom lengths available on request.

The benefit of reduced capacitance is most apparent with sources that have high output impedance, especially certain tube stages or phono preamps, where the cable’s capacitive load directly affects frequency response. With a modern source featuring low output impedance and a short connection, the margin is narrower. Holger Wachsmann, who developed AIR technology at in-akustik, sums up his objective in these terms: a good cable is not the one that gets the most out of a system; it is the one that loses the least of the original signal.

Technical specifications

Technologies

• AIR Helix Point-to-Point for authentic sound
• Air as the ultimate dielectric, minimizing capacitance
• Cross Link Super Speed waveguide for balanced sound
• Dual mono configuration
• Compliance: CE, REACH, RoHS

Cable design

• Design: coaxial
• Cable diameter: 13 mm
• Dielectric: air
• Conductor structure: Cross Link Super Speed waveguide
• Conductor material: high-purity OFC copper
• Shielding: dense, tin-plated copper braid (oxidation protection)
• Jacket: PE network jacket

Connectivity

• Connectors: 2 x RCA to 2 x RCA
• Highlight: RCA SL (solderless)
• Connector housing: solid metal
• Contact material: tellurium copper
• Contact treatment: rhodium-plated
• Connector assembly: pressure-crimped contacts at a force of 1.5 tonnes for a precision fit

Available lengths

• Length: 1 m, 1.5 m, 2 m