Floorstanding loudspeakers — Russell K Red 120

The Red 120 is the smaller floorstander in the Red series from Russell K, the loudspeaker company of designer Russell Kauffman, with speakers made in the UK and Poland. Russell K is known for building cabinets with no internal damping material, controlling internal energy through bracing and crossover design instead. The Red 120 offers more bass than the Red 50 stand-mount in a floorstanding cabinet with a smaller footprint than many stand-mounts once their stands are counted.

Key specs that matter

The Red 120 is a 2.5-way design with a 25mm soft-dome tweeter and two 5-inch (127mm) impregnated-paper-cone drivers - an upper mid/bass unit and a lower bass unit. Crossover points are 80Hz and 2.2kHz. Frequency response is 25Hz to 22kHz, sensitivity is 86dB/W/m and impedance varies between 4 and 8 ohms. Each speaker measures 910 x 200 x 190mm (H x W x D, including plinth, base and spikes) and weighs 16kg. Finishes include walnut, oak with a black baffle, black, piano black and piano white.

Engineering and use context

In a 2.5-way layout, the upper unit handles the midband as well as low frequencies, while the lower driver adds output only in the bass, rolling off at 6dB per octave above the lower crossover point. Instead of wadding, three shelf braces with holes sit below the drivers, each with a different number of holes tuned by listening, so that midrange energy is trapped in a small section of the cabinet, damping it around 100Hz, while the whole volume works together for the deepest bass. A fourth, solid brace carries an internal port that vents into a small internal chamber, which connects to the room through the visible reflex port, and the complete system is tuned to about 24Hz. The panels are relatively light 16mm MDF with a 19mm front baffle. The crossover is minimal - all three drivers are connected in positive phase with only one component directly in each driver's signal path. The tweeter is attenuated by a modified Zobel network rather than a conventional L-pad, leaving a single capacitor in series with it, and the mid/bass driver uses a custom enclosed-field ferrite-core inductor chosen for very low DC resistance. The drivers were chosen by hand-holding candidates in free air to judge them before cabinet testing.

Pairing

Given its modest sensitivity and a load that dips towards 4 ohms, the Red 120 benefits from an amplifier of moderate to high power. The distance from the rear wall is best set carefully by ear, as the low-tuned reflex system interacts with the room boundary.

Alternatives

Russell K's own Red 120Se is the upgraded version of the same cabinet, with bass extension to 22Hz and higher weight.