Triangle OPERA OS10C (10 m spool)

Connecting an amplifier to speakers does not require an exotic cable, but copper with a sufficient cross-sectional area that retains its qualities over time. The Opéra range from Triangle meets this need with 2.5 mm² tinned copper conductors, supplied here on a ten-metre reel that you cut to the required length. The transparent jacket has polarity markings to prevent connection errors.

Tinned copper that resists oxidation

Each conductor is made of oxygen-free copper strands (OFC, for Oxygen-Free Copper) with a purity of 99.99%. Triangle adds tinning: the strands receive a thin layer of tin. Bare copper eventually darkens when exposed to air, especially at the stripped ends clamped into terminals, and this oxidation gradually degrades the quality of the contact. Tin protects the copper from this ageing, and the brand highlights the resulting longevity. Tin conducts less effectively than copper, but the layer is very thin and, at audible frequencies, current flows through almost the entire thickness of the strands: its effect on the cable’s resistance is negligible.

The strands are assembled in a helical braid, meaning they are wound in a spiral around the conductor’s axis. This arrangement makes the cable flexible, allowing it to follow a furniture corner or the edge of a skirting board easily, while the strands stay together once the jacket is removed.

A 2.5 mm² cross-section suited to domestic cable runs

The cross-section, expressed in square millimetres, is the area of copper in each conductor. The larger it is, the lower the cable’s resistance and the better the amplifier maintains control of the speaker drivers, especially in the bass, where the current demand is highest. At 2.5 mm², resistance is around 0.014 ohm per metre of cable run, including both outgoing and return conductors. Over 5 m, a common distance between an amplifier and a speaker in a living room, it stays below 0.07 ohm: less than 2% of the impedance of a 4-ohm speaker, and less than 1% for an 8-ohm speaker. This margin covers the vast majority of installations; beyond around fifteen metres per speaker with a 4-ohm load, a larger cross-section becomes appropriate.

The 2.5 mm² cable remains thin enough to fit all screw terminals, standard banana plugs and most spring terminals still found on some compact amplifiers.

A transparent jacket that guides connection

The transparent PVC reveals the copper and carries three markings: polarity, length and a direction indicator. The polarity marking is the most useful, distinguishing one of the two conductors so you can connect the amplifier’s + to the speaker’s +, and - to -, at both ends. A speaker connected the wrong way round operates out of phase with its neighbour: the bass weakens, the stereo image becomes diffuse, and the problem often goes unnoticed at first. The length markings make cutting easier without a tape measure, and the direction indicator helps orient the cables the same way from one speaker to the next.

Ten metres to distribute according to your room

The reel format lets you decide the length of each cable run. Ten metres covers a pair of speakers positioned up to 5 m from the amplifier, or an asymmetrical arrangement when the furniture is not centred, with 3 m on one side and 7 m on the other, for example. The same reel can serve the three front channels of a small home cinema system (left, centre, right) if the distances remain short. For a complete system with rear channels, the Opéra range is also available on 5 m and 100 m reels.

Triangle developed this cable to accompany its own speakers, but it is a standard conductor that connects to any passive speaker and any amplifier with binding posts.

Technical Specifications

General Specifications

• Length: 10 m
• Section: 2 × 2.5 mm²

Construction

• Oxygen-Free Copper (OFC) conductors
• Anti-oxidation treatment