Bookshelf Speakers — Russell K Red 50

The Red 50 is the smallest stand-mount loudspeaker in the Red range from Russell K, the British company run by designer Russell Kauffman. It is a two-way reflex box built around a 5 inch paper-cone woofer and a 25 mm soft dome tweeter. At launch the pair cost GBP 975 in real wood veneer and GBP 1,099 in gloss black, with optional grilles sold separately at GBP 85.

Key specs that matter

Russell K quotes a frequency range of 45 Hz to 22 kHz. The woofer uses an impregnated paper cone driven by a 25 mm voice coil wound on aluminium, with a high-power ferrite magnet and a Faraday copper ring intended to cancel distortion. The tweeter also relies on a ferrite magnet and a copper ring, and it uses copper-clad aluminium coil wire on a fibreglass former. The two drivers meet at a nominal 2,200 Hz with a 12 dB per octave slope. The rear reflex port is tuned to 55 Hz. Each cabinet measures 310 mm high, 205 mm wide and 200 mm deep. Finishes are real wood veneer or a deep automotive-grade lacquer.

Engineering and use context

Russell K uses 16 mm MDF on the sides, top and back, while the front baffle is 19 mm thick. Instead of lining the walls with damping material, Russell K leaves the cabinet undamped and fits an acoustic loading shelf with eight apertures above the woofer, which acts both as bracing and as a tuning element for the internal air volume. Both drivers are wired in positive phase, and the network places just one part in series with each driver, keeping the crossover as simple as possible. Woofer and tweeter share the same approach to magnet design, both using ferrite rather than neodymium. The binding posts on the back are mounted in an unusual orientation, which means spade connectors have to be slid on sideways instead of vertically.

Pairing

The amplifier choice rests on the small woofer and the modest cabinet volume, which suit a compact integrated amplifier in a room of around 20 m2. Solid stands bringing the tweeter to seated listening height suit it, and the port on the back panel needs free space behind each cabinet. Spade connectors have to suit the side-entry terminals.

Alternatives

The Russell K Red 100 is the larger standmount in the Russell K catalogue, using a 165 mm bass-mid driver and a front port tuned to 35 Hz.