From Hi-Fi World - September 2014  issue
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Piano Forte

Noel Keywood is beguiled by a beautiful-looking new floorstanding 'speaker from Yamaha.

So stereo loudspeakers are ugly boxes that blight the living room. If that’s a view you’ve heard from - er - other members of the family, then harmony and even happiness might be improved by Yamaha’s lovely NS-F901 loudspeakers, priced at £2999. “The cabinets have Yamaha’s signature piano black finish and are designed by Toshiyuki Kita, whose work is featured in the permanent collections of museums all over the world, including the Museum of Modern Art in New York and Centre Georges Pompidou in Paris” Yamaha tell us. 

   Brushed aluminium trims and white driver cones contrast well with the deep gloss black lacquer finish of the NS-F901s to give the eye a treat. OK, they are still big loudspeakers but they do have a classy air about them, making a clear statement of quality. It isn’t one subverted by reality either: the NS-F901s feel beautifully made in the flesh. 

   At 30.5kgs the NS-F901s are heavy, but not cripplingly so. Internal bracing aids cabinet strength and rigidity to the 106cm high cabinets (when on their spikes). That figure puts them in the popular 1m high floorstander category, which these days an overwhelmingly large number of loudspeakers occupy, so the Yamaha’s fit in with the crowd. 

   The cabinets have non-parallel sides to lessen discrete resonances, as well as slanted internal baffles and braces for the same reason; symmetry is not wanted in loudspeaker cabinets because it promotes discrete resonances, or so popular supposition has it. In practice I have found when designing loudspeaker cabinet chambers it isn’t so simple; chambers have discrete resonances no matter how weird you make ‘em, but their Q is usually reduced, measurement shows, so asymmetry does help, if not for reasons commonly quoted.

   Two 61/2in bass units can be seen at the bottom of the vertical drive unit array. Above sits a 5in midrange driver with a shallow cone; at top sits a 1in aluminium dome tweeter. Yamaha’s bass and midrange units use polymer injected mica diaphragms, hence their whiteness. They are extremely light, Yamaha say, and are rigid and stable for smoothness, a very fast response and good dispersion. The frames are made from rigid die-cast aluminium and the magnet of the midrange is a powerful neodymium type, able to concentrate flux around the small, light voice coil. The bass units are of similar construction but use larger ferrite magnets. 

   The two bass units are reflex loaded by a large front facing port. This may look good, directing low bass to the audience it would appear, but generally it is avoided because box colourations are also directed to the audience; it is after all simply a large hole in the cabinet (in which air resonates). Bass wavelengths at the port frequency are no less than 30-40ft, far larger than the cabinet’s dimensions so where the port is placed, front or rear, is acoustically unimportant - and that’s why ports are usually rear mounted.  

   The plinth at the base of the cabinet is only that; there is no hidden port. Height-adjustable feet are fitted as standard, and spikes are supplied as options. Rear connection panels carry large, gold-plated screw terminals that accept bare wires, spade terminals (USA) or 4mm banana plugs (Europe). Bi-wire links are fitted and must be removed if bi-wiring is to be used. The piano gloss finish of the cabinets extends all the way around to include the rear panel, a nice point.