Floorstanding loudspeakers — Yamaha NS-F51

The NS-F51 is a passive floorstanding loudspeaker from Yamaha in a two-way, three-driver arrangement, with two bass cones and a single soft dome tweeter, loaded by a reflex port. Yamaha pitches it for films, CDs, MP3 files and streaming music, and offers it in walnut or black. Its UK price was GBP 219.95.

Key specs that matter

The woofers are a pair of 16 cm (6-1/2 inch) cones and the tweeter is a 3 cm (1 inch) soft dome. Yamaha lists a frequency response of 43 Hz to 26 kHz and a sensitivity of 89 dB at 2.83 V and 1 m, with a nominal impedance of 6 ohms. Input power is rated at 80 W nominal and 240 W maximum. Each speaker is 233 mm wide, 973.5 mm tall and 254 mm deep and weighs 13.7 kg.

Engineering and use context

The height of the enclosure is the main design lever here. The tall cabinet has a large internal volume, which Yamaha uses to extend bass output from two moderate-size cones rather than a single larger driver. Internal bracing is added to suppress panel resonance. The cabinet edges are rounded to cut diffraction at the baffle. In the crossover network the parts are mounted on a wooden circuit board instead of a conventional one. A front grille covers the drivers, and with its curved form the speaker aims for a furniture-like look in either veneer. Because both woofers and the tweeter share a simple two-way filter, the design keeps the part count lower than a three-way layout. The two woofers run in parallel over the same band, so their combined cone area rather than cone size sets the output available in the bass. The profile is tall and narrow, and one person can move a speaker without help.

Pairing

The 6 ohm load and fair sensitivity are an easy match for most AV receivers and stereo integrated amplifiers that support 6 ohm speakers, and the power ratings above set a reasonable range for amplifier output. The slim footprint makes the pair practical as front speakers in a living room of around 20 m2, where a separate subwoofer can take over the lowest octave for film playback.

Alternatives

Yamaha's NS-F350 is a heavier three-way tower with a separate 13 cm midrange, an aluminium dome tweeter and a 1,157 mm cabinet.