Bookshelf Speakers — Russell K Red 100

The two-way Red 100 stand-mount was the first model released by Russell K, a British company founded by designer Russell Kauffman, who previously worked on loudspeakers for B&W and Morel and created the Fat Lady system for Morel. The speaker is designed in Great Britain and built in Europe. The range later grew to three models, with the smaller Red 50 stand-mount and the Red 150 floorstander placed around it. UK pricing runs from GBP 2,795 to GBP 3,525 per pair depending on finish and whether grilles are included, and the Italian price for the wood version was EUR 1,990 per pair.

Key specs that matter

A 25 mm soft dome tweeter works above 2,200 Hz, and a 165 mm woofer with an impregnated paper cone handles everything below. Nominal impedance is 8 ohm and sensitivity is 86 dB. The quoted frequency range is 30 Hz to 20,000 Hz, measured in room rather than in an anechoic setting. Each cabinet stands 400 mm high, 260 mm wide and 270 mm deep and weighs 10 kg. Buyers choose between black oak with a black baffle, oak with a white baffle and walnut with a black baffle.

Engineering and use context

Russell K builds the enclosure from 16 mm MDF on the sides, top, bottom and back, with a 19 mm front baffle, and leaves it completely free of damping material. Instead of wadding, two shelves with several apertures sit above and below the woofer to brace the walls and load the driver acoustically, keeping midrange energy contained. A front-facing reflex port is tuned low, to 35 Hz. The woofer uses a high-power ferrite magnet, a 25 mm voice coil on an aluminium former and a Faraday copper ring to cut distortion. The tweeter has a dual ferrite magnet system, copper-clad aluminium wire wound on a fibreglass former and its own Faraday ring. The crossover follows a nominal 12 dB per octave slope and puts only one component in the signal path of each driver - a single low-resistance inductor with an enclosed ferrite core feeds the woofer, and one capacitor feeds the tweeter. Level matching for the tweeter is done with an offset Zobel network, and the handover region is optimised for phase.

Pairing

The Red 100 carries a power rating of 100 W. Its binding posts accept several termination types, including spades. Matching 60 cm stands are offered for the speaker.

Alternatives

The Russell K Red 50 is the smaller stand-mount, using a 13 cm woofer in a 310 mm high cabinet weighing 6 kg.