Yamaha NS-1000M Floor standing speakers
The Yamaha NS-1000 is produced in two versions, domestic and professional, the former in ebony with dark brown front grille, the latter (NS-1000M) slightly less expensively in plain black with a perforated protective metal cover over the low frequency unit; both are supplied in left/right matched pairs. The cabinets are very substantially made in 20mm veneered particle board with extensive internal bracing, damping pads on all surfaces and fibreglass filling. The units utilize machine-turned cast frames and some of the largest ceramic magnets I have seen. The multi-element crossover network is built on a plastics moulding shaped to accommodate the individual components, and this moulding also incorporates rear connecting terminals of the spring-clip type; the complete assembly, with its unusual inductors wound on ferrite bobbins and high-quality polyester capacitors, can be withdrawn from the rear.
Three units are used: a 300mm paper cone handles the low frequencies up to 50Hz, a 88mm dome mid-range on up to 6kHz and a similar but smaller 30mm dome above this. The use of beryllium as a diaphragm material for these two domes is a considerable Yamaha achievement because, although this metal has the very desirable properties of light weight and great rigidity, it is almost unworkable. Yamaha have developed a technique of vaporizing a solid chunk and vacuum depositing on a former which is subsequently removed to leave an extremely thin but strong dome free from the internal stresses often associated with pressings. However, because beryllium is rather active chemically, it has then to be coated with a protective layer. When this has been done, the final product should possess the near ideal piston characteristics which loudspeaker designers seek. (I am often asked how one reconciles this need for rigidity with the so-called soft dome units now in common use, and the answer is that the latter are all coated with viscous materials which can only flex slowly so that at high frequencies the required displacement has taken place before the coating permits any loss of motion.)
How they performed
On connecting up and listening it was immediately obvious that the NS-1000 covers a very wide frequency range. Constant impedance attenuators are provided for the mid-range and treble units giving a range of adjustment between 3dB above normal down to complete shut-off. In the event my final choice came back to the marked level position. Low-frequency response from an enclosure of this size was remarkably extended and, although it fell off in amplitude at the extreme bottom end where the organ growls amiably, it was possible with a little help from the amplifier bass control to produce a very happy result indeed. Investigation showed that the free-air resonance of the roll-surround bass unit was as low as 16Hz, suggesting that a very heavily weighted voice-coil had been used, any loss of sensitivity being compensated by the hefty magnet; consequently this low-frequency resonance rises to only 38Hz in the sealed enclosure, permitting this unusually extended response. In spite of the heavy internal damping though, it was possible to detect some traces of hangover at low frequencies; for example the timpani and bass drum on the remarkable Colin Davis/Concertgebouw Rite of Spring (Philips 9500 323, 3/78) sometimes seemed a trifle flabby and certainly less than accurate.
At the other end of the scale, extreme treble is excellently maintained, always bright, active and with an overall liveliness, yet unmarred by an excess of scintillating highlights. In the midrange I was less happy and detected some quite marked evidence of colouration which often imparted an unnatural accent to voice and many instruments. It had been noticed that the protective metal grille over the bass unit 'rang' quite markedly when tapped and it was immediately suspected of being party to this undesirable trait; however, it was absolved by experiment and further listening tests led to an immense amount of upping and downing of the level controls in an attempt to get things better if not right, but the effect proved unamenable to correction and is almost certainly due to resonance characteristics rather than errors in frequency response; the latter, on a quick check, seemed remarkably flat. Distortion was at a very low level indeed and is a notable characteristic of this loudspeaker; furthermore it did not rise disproportionately when the 100 watts-per-channel test amplifier was operating near maximum. Efficiency is perhaps a little above average, so this 200 watts produced a very considerable volume of sound. Impedance is quoted as 8 ohms but in fact falls as low as 5.5 ohms at a couple of points in the range; this should not unduly embarrass any reasonable source, although it improves the apparent efficiency.
Overall this Yamaha NS-1000 must be considered as a very superior example of Japanese design. My pair could certainly be operated successfully at dauntingly high volumes and they return the clear open sound at all times which is characteristic of low distortion levels. For me the colouration which seems to centre around the octave from 750Hz to 1,5kHz mars an otherwise admirable loudspeaker and it is enough to prevent me from praising it as highly as some others have done. Construction and finish throughout are of the highest standard and one could also expect reliability to be high. As I loaded them aboard my car, I had the final thought that if 'lbs' for '£s' are to be any criterion Yamaha must register a plus point; at 3lkg for the M version and 39kg for the domestic example this is not the loudspeaker to choose for portability.
