Floorstanding loudspeakers — Fischer & Fischer SN/SL 670

The SN/SL 670 belongs to the three-way passive towers in the slate catalogue of Fischer & Fischer, the loudspeaker company located in Schmallenberg, Germany. Above it, the brand lists only the four-way SN/SL 770.1 AMT and SN/SL 1000.1 AMT. As across the range, the SN finish leaves the slate with its natural surface, while SL adds polishing and a lacquer finish in any RAL colour or an available automotive shade.

Key specs that matter

Two 220 mm Fischer & Fischer cones with carbon paper foam sandwich membranes cover the bass. The midrange is shared by two 180 mm cones of carbonized paper and carbon foil sandwich, each with an aluminium phase plug, and the treble unit is an Air Motion Transformer produced specially by Mundorf. Fischer & Fischer quotes 24 Hz to 27,000 Hz (plus or minus 3 dB), a 4 ohm impedance, 92 dB sensitivity at 1 W and 1 m and 112 dB peak acoustic pressure. Slate cabinet dimensions are 1260 x 275 x 420 mm, rising to 1320 x 380 x 475 mm including the floor system. A single speaker weighs 129 kg.

Engineering and use context

Unlike the single-piece enclosures of the smaller models, the 670 has a two-part slate cabinet with walls of 20 and 23 mm. Loading is bass reflex, and its network uses phase and impedance corrected filters of 1st and 2nd order. The brand's view is that slate, with its flaky layers and extremely high mass, does not resonate the way wooden panels do, so driver energy goes into the air, and that the material makes cabinets possible in sizes suited to homes. It also cites the mass reactance of the stone as keeping the baffle from moving with the tweeter membrane. Height adjustment comes from a levellable aluminium floor system. The maker describes its slate as soil compressed into rock over nearly half a billion years. Across the whole catalogue there are 13 models, from the small two-way klein to the highest-numbered four-way SN/SL 1000.1 AMT.

Pairing

Its bi-wiring panel carries 63 A rhodium plated posts with pure silver bridges. Owners may connect one cable pair per side or separate runs for the upper and lower sections. An amplifier specified for the low nominal impedance is required. Fischer & Fischer says it can bring older speakers up to date with newer technology. The company adds that it uses chassis and components from top manufacturers worldwide.

Alternatives

The Fischer & Fischer SN/SL 770.1 AMT is a tri-wired four-way floorstander with three bass cones, rated at 92.5 dB and weighing 159 kg.