Jean-François
Nothing to report
This cable does the job
Comment from September 10, 2026 — Experience from August 23, 2026
Automatically translated — Show original (French)
Rien a signaler
Ce câble fait le job
Ce câble fait le job
NorStone Classic B250 black
Overview
The black Classic B250 sets a remarkable quality standard in the affordable speaker cable segment. This 2 x 2.5 mm² cable uses high-purity OFC copper and a carefully designed multi-strand construction to faithfully transmit the audio signal between amplifier and speakers. Designed by French brand Norstone, this cable combines technical performance with easy installation thanks to its polarity identification system integrated into the black sheath.
Technical construction and exceptional materials
The Classic B250 is based on a 7x31 twisted-strand conductor architecture, comprising 217 fine strands of 99.99% pure OFC (oxygen-free) copper. This multi-strand construction offers a double advantage: installation flexibility and optimal conductivity. Twisting the strands limits electromagnetic interference while preserving signal integrity throughout the cable length.
OFC copper differs from standard copper through the absence of oxygen in its crystalline structure. This technical characteristic significantly reduces linear resistance to 0.008 Ω/m, around three times lower than a conventional household cable. Its capacitance of 55.350 pF/m remains well within acceptable values for preserving the dynamics of high-frequency signals.
The flexible PVC sheath, measuring 8 x 4 mm, incorporates a unique identification system: one round-section conductor (positive polarity) and another rectangular-section conductor (negative polarity). This tactile distinction greatly simplifies installation, even in darkness or confined spaces.
Smart installation and polarity identification
Norstone has developed a comprehensive marking system to eliminate wiring errors. In addition to the different sheath shapes, the cable features directional markings indicating the recommended direction of reading (from the amplifier to the speakers) and regular metric markings.
This attention to practical details is particularly useful in complex home theater installations, where wiring multiple satellite speakers can quickly become confusing. Respecting polarity ensures a coherent stereo image and a natural soundstage, while accidentally reversing polarity results in an unnatural shift in sound source positioning.
The 2 x 2.5 mm² cross-section allows a maximum current of 38 amperes at 300 volts of insulation, values far exceeding household requirements but demonstrating the robustness of its construction.
Versatile use and extensive compatibility
The Classic B250 is ideally suited to medium- to high-power speakers: floorstanding speakers, large bookshelf speakers, studio monitors, and home theater satellite speakers receiving dedicated amplification. Its 2.5 mm² cross-section is particularly suitable for distances over 10 meters, where the cable’s linear resistance can become audible with smaller cross-sections.
In a stereo hi-fi installation, this cable works effectively with amplifiers delivering between 50 and 200 watts per channel. For home theater, it is suitable for 5.1 to 7.2.4 systems, particularly for connections to rear speakers and active subwoofers requiring substantial cable lengths.
The flexibility of the sheath makes it easy to route through technical conduits, baseboards, and cable trunking. The cable withstands tight bends without permanent deformation or alteration of its electrical properties.
Technical Specifications
Electrical Specifications
- Conductor: 99.999% OFC copper (ultra pure)
- Cross-section: 2 x 2.5 mm²
- Linear resistance: 0.008 Ω/m
- Capacitance: 55.530 pF/m
Recommended Applications
- Floorstanding speakers with powerful amplification
- High-end stereo Hi-Fi systems
- Home Theater setups
- Front speakers
- Surround speakers
- Long distances up to 15 meters
- Universal compatibility with any Hi-Fi or Home Theater system
Key Features
- 99.999% OFC copper: outstanding conductivity, extremely low resistance
- Excellent reproduction of micro-details as well as strong dynamics
- 2.5 mm² cross-section: perfect for powerful speakers or long distances
- Versatile use: floorstanding, bookshelf, or surround speakers
Frequently Asked Questions
What is the difference between OFC copper and standard copper?
OFC (Oxygen Free Copper) contains less than 10 ppm of oxygen, compared with 200–400 ppm for standard copper. This higher purity reduces electrical resistance and improves audio signal transmission, particularly noticeable over long distances. The OFC manufacturing process removes oxygen by melting under a controlled atmosphere, creating a more homogeneous crystal structure.
Can this cable be used for bi-wiring or bi-amping?
Yes, the Classic B250 is perfectly suitable for bi-wiring. Simply use two separate cable runs between the amplifier and the speakers’ dual terminals, removing the metal jumpers. For bi-amping, each amplifier has its own connection to the dedicated drivers (bass/treble). The 2.5 mm² cross-section easily handles the distributed power.
What maximum length can be used without audible degradation?
With its resistance of 0.008 Ω/m, the B250 maintains excellent performance up to 20–25 meters in home use. Beyond that, the cable’s total resistance begins to affect the amplifier’s damping factor, which is particularly noticeable in the bass frequencies. For distances over 30 meters, a 4 mm² cross-section becomes preferable.
How can polarity errors be avoided during installation?
Norstone’s marking system makes installation much easier: round sheath for positive (+), rectangular for negative (-). Also follow the direction of the markings (from the amplifier to the speaker). If reversed, the typical symptom is an off-center stereo image with blurred vocals and reduced bass. There is no risk of damage to the equipment.
Is this cable suitable for home theater systems with [in-wall speakers](/categories/1002-enceintes-encastrables-murales-in-wall)?
Absolutely, the Classic B250 excels in this application. Its flexible sheath makes it easy to route through walls, and its linear resistance compensates for the long distances typical of in-wall installations. The 2.5 mm² cross-section handles the satellite and center speakers of most home theater systems perfectly, including with amplifiers delivering 100–150 watts per channel.
Does this cable require a break-in period?
Unlike active electronic components, cables do not require break-in in the strict sense. However, some users report a stabilization of performance after 20–30 hours of use, attributed to the relaxation of internal mechanical stresses and the homogenization of contacts. These variations remain subtle and do not call initial performance into question.
User reviews
Review highlights
- Nearly unanimously praised with a 4.9/5 rating from 60 reviews, this cable is seen as offering unbeatable value for money.
- Its great flexibility and ease of installation are widely praised: it fits easily into a cable trunking or conduit.
- The visual distinction between the two conductors (round cross-section and square cross-section) is highly appreciated for easily identifying the + and - polarities.
- Customers confirm that it performs perfectly over long distances, particularly for home theater installations in 5.1 or 7.1 configurations.
Based on reviews from customers who purchased this product, summarised by AI
Jean-françois
Simple and effective, installation and age verification OK
Comment from August 25, 2026 — Experience from August 14, 2026
Automatically translated — Show original (French)
Simple et efficace, installation et déni d’âge ok
Pieter
Easy-to-handle cable. Flexible and easy to conceal in a cable duct.
Comment from August 09, 2026 — Experience from July 16, 2026
Automatically translated — Show original (Dutch)
Goed hanteerbare kabel. Soepel en makkelijk weg te werken in een kabelgoot.
- Eco-contribution of €0.02 included in the sale price.
- Manufacturer reference: NORB250100
- GTIN / EAN: 3760108804883
