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. 

Removing the blue wire links allows bi-wiring; sturdy gold plated terminals accept 4mm plugs, spades and bare wire.

SOUND QUALITY

As always the NS-F901s were run in heavily, using pink noise, then music, then a Monitor Audio De-tox/run-in CD. We took them to 60 hours before listening, which is plenty enough for most loudspeakers, and sounded right in this case - they lost a light midrange patina and developed a sense of depth. Speakers with Kevlar cones and diamond domes need 200 hours and Tannoy Westminster Royal SEs need 8 months whilst the woods settle, I am told! 

   The drive system comprised Quad QMP monoblocks, driven by a Mirus Invicta DAC (reviewed this issue), fed by an Astell&Kern AK120 acting as a digital transport, playing CD and high-resolution digital up to 24/192. Also feeding the Quads directly was an Icon Audio PS3 valve phono stage (it has a volume control) hooked up to a Timestep-tuned Technics SL-1210 MkII Direct Drive turntable with SME309 arm and Ortofon Cadenza Bronze moving coil cartridge. 

   Moving up and down in front of the speakers confirmed that they focussed properly low down, as measurement had suggested, imposing a low optimal seating height. I had to remove the rear feet and unscrew the front feet to their limit to tilt the cabinets back to correct this, and still a little more backward tilt was required – so ideally the legs need to be longer. I sat reasonably low, ear height 100cms, 350cms away (11.5ft) in our 25ft long listening room. 

   Appropriately, I really ‘got’ these loudspeakers when listening to Benjamin Grosvenor playing (superbly) 'Chopin’s Nocturne No5' (24/96). His piano sounded wonderfully pure, the notes having a lovely fresh and elaborate character to them that came from the instrument rather than the loudspeaker, I felt. 

And they drifted outward nicely at me with no hint of being anchored to the cabinet, such unfettered purity being a sign of low colouration. I rather suspected someone from Yamaha’s famous piano division had sat in on the voicing of the NS-F901s when listening to this. If you want a loudspeaker that captures the sound of a great piano, these are the ones. 

   This gorgeous performance immediately placed the Yamaha’s in a particular mould: they are an academically refined and extremely well considered loudspeaker, I learnt from this and other performances. 

   So on to John Coltrane playing 'It’s Easy to Remember' (24/96), a laid-back performance that moves at a slow gait with Coltrane’s saxophone sounding richly metallic and smooth as it drifted from the left loudspeaker (piano occupies centre stage in this piece), the final drum roll delivered powerfully by the right loudspeaker. The Yamaha’s delivered this remaining clean and composed and spry; they are not heavy or wallowy or boxy, but very nimble.

   With Diana Krall’s 'Narrow Daylight' (24/96) I realised the Yamahas are deeply insightful, teasing out every little whisper of breath from Diana Krall at the microphone. The final guitar solo cut out with tremendous speed, and the strings were vibrant and had sonic texture; they were palpably alive and forceful too, yet there was no laceration, no sting and no hardness; the tweeter sounds sweet. Meanwhile the prominent bass line was nicely supported, although there was a smidgen of box thrum here. 

   Tom Petty belted out 'Refugee' (24/96) with pace and vigour and again I heard every nuance of his vocal inflexions; the Yamahas again showed themselves to be extremely revealing. Here I detected a hint of forwardness, or lifting of detail; the Yamahas are not backward in coming forward, but their projection is subtle. There was plenty of space around Petty – and drums lay a few paces behind him; a sense of depth was apparent. Drums and bass were firm and fast, clean too, with a slight boom from the box, through the port, evident at times, but subsonics are muted, this keeping the speakers sounding tight and fast. This particular track commonly sounds a little harsh but the NS-F901s sounded almost magically clean and pure again, a very welcome feature.

   Spinning Phil Collins singing 'I Don’t Care Anymore' (180gm audiophile pressed LP), initially with an Ortofon 2M Black MM cartridge had the man sounding light in character, drums fast but lacking body and the soundstage a tad flat in perspective. Going back to our usual Cadenza Bronze largely corrected all these factors, showing how critical the Yamahas could be. They are very revealing and have strong upper midrange projection, so a preceding system without these traits is needed to achieve balance. Where I used the Mirus Invicta with the ESS Sabre’s Slow filter engaged to ensure smoothest digital, with LP I had to use a quality moving coil; MMs won’t do (the 2M Black is a bit shiny up top).

   With Mark Knopfler’s 'True Love Will Never Fade', from 'Kill To Get Crimson' (an audiophile pressing) I could hear every little detail of his finger work on the guitar’s strings and there was again a lovely sweet quality to treble. This track, that I use a lot for review work because it is so well recorded and pressed, confirmed that the NS-901s push vocals forward, due to their strong upper midrange. They lack the slight softness common in so many speakers, imposed by their crossover dip. This helps explain their tremendous detailing and insight but I knew that if I span 'Please Please Me' (1963) it would be overly analysed - and this was the case. 

   Moving on to a modern, well-balanced recording on 200gm audiophile vinyl, Kate Bush singing 'King of the Mountain', the strong reggae bass line rolled out fluidly whilst La Bush trilled clearly centre stage, every word sharply outlined and obvious. As the organ on 'Pi' drifted out, the sheer tidiness and sophistication of these speakers made itself obvious. They’re a little over-revealing for older recordings perhaps, but with modern material that has a natural balance and is well recorded, they fly. 

CONCLUSION

Think of the NS-F901s as highly crafted loudspeakers that offer a sound characterised by poise and sophistication. They are smooth yet very insightful, pushing vocals and instruments out to listeners. Having neither excessive bass or treble, minimal colouration, but quite a forceful air, they were dynamically lively and engaging to hear. Classical listeners in particular will love their poise and refinement, but they played rock well too. The NS-F901s are true sophisticates, reflecting the pedigree of their manufacturers, Yamaha, who are also famous for their piano division.

YAMAHA NS-F901 £2999

OUTSTANDING - amongst the best.

VERDICT

A beautifully built and finished loudspeaker with a sophisticated sound. Exudes quality in every area.

FOR

- smooth, clear and accurate

- highly insightful

- rich cabinet finish

AGAINST 

- inadequate tilt adjustment

- forward upper midband

- occasional bass bloom

 Yamaha

+44 (0)844 811 1116

www.uk.yamaha.com

MEASURED PERFORMANCE

Our frequency response analysis shows a nice even result right across the audio band, with a small amount of lift around 6kHz, enough to add just a fraction of ‘light’ onto the sound, without obvious brightness. There is absolutely no sign of any crossover dip around 3kHz that can soften the sound, and detail delivery will be strong. This was an optimum result, with our measuring microphone on the axis of the top bass midrange unit. Moving it up or down introduced phase dips, suggesting phase alignment of the drivers wasn’t perfect – a surprise considering Yamaha’s technical ability and high technical standards. This was attributable to wide driver spacing, a styling imposition; high frequency drivers need to be very close, less than half a wavelength.  

   Bass extends down to 50Hz, a port frequency of 34Hz working to support lower bass output. The NS-F901 goes low and should deliver firm deep bass, these results suggest. Because there is no bass peaking, quality will be good and balance accurate.

   Sensitivity was very high, measuring a good 90dB sound pressure level from one nominal Watt (2.8V) of input – and with a measured impedance of 7 Ohms overall this was a real Watt, meaning the Yamaha’s are efficient. They need little power to go loud, 40 Watts being plenty enough for high volume. The impedance curve is normal enough, with twin residual and reactive peaks around port resonance that these days are commonly tuned out, a trick Yamaha have missed. 

   A 200mS decay analysis showed the speakers to be clean across midband and treble, but suffering box overhangs below 200Hz that correlate with bumps in our frequency response analysis. The box is quite lively, a decay map showing it is relatively ‘hot’ in the bass regions, likely to add fullness at least to bass. 

   The NS-F901 measured well, if with minor flaws. It is, all the same, accurate, has low coloration and is very sensitive, all properties that will ensure a high standard of sound quality. NK

FREQUENCY RESPONSE

Green - driver output

Red - port output

IMPEDANCE