YAMAHA NS-890
¥ 89,000 (1 unit, around 1978)
Commentary
This is the first 4-way speaker system for Yamaha that uses Yamaha's high-purity beryllium diaphragm for mid-range and high-range applications.
A 30 cm cone type woofer is installed in the low range.
The cone paper is a conical type with corrugation to suppress split vibration and obtain a wide piston area. In addition, a roll edge of foamed urethane with excellent airtightness is used for the edge. In addition, the linearity of the damper supporting the vibration system has been improved by careful consideration of the material and impregnation agent.
The magnetic circuit uses a ferrite magnet of 156 φ mm and weight of 4.4 kg, obtaining a total magnetic flux of 200,000 maxwell and a magnetic flux density of 10,000 gauss.
Du Pont's nylon fiber Nomex is used for the voice coil bobbin. Since the long voice coil is edgewise wound with copper ribbon wire, the voice coil does not deviate from the magnetic field even at the time of large input, and excellent linearity is obtained. In addition, the center pole is covered with a copper cap to suppress annoying third harmonic distortion over the entire band.
A 12 cm cone type midbus is installed in the middle and low range.
The cone paper is made of carefully selected materials for a lightweight finish. The voice coil is wound with heat-resistant copper ribbon wire with high space factor and has a size of 42 φ mm.
The edge is made of cloth specially processed with resin-based material, and the linearity is sufficiently high for the amplitude in the used band.
The magnetic circuit is a 90 φ mm ferrite magnet with a weight of 1 kg, a total magnetic flux of 60,500 maxwell and a magnetic flux density of 11,300 gauss.
In order to avoid the influence of the woofer, there is a back cavity on the back, and glass wool is packed to suppress unnecessary resonance.
Mid-high with 50 φ mm with 50 φ mm dome type beryllium diaphragm mid-high.
The diaphragm, which takes advantage of the characteristics of beryllium material, is directly connected to a heat-resistant copper ribbon edgewise wound voice coil. It is supported by a special fiber tangential edge with double coating of viscoelastic resin and thermosetting resin.
In addition, by opening an air hole in the outer pole on the back side of the edge, the movement of the edge is made smooth and further linearity is obtained.
The magnetic circuit uses magnets of 100 φ mm, 1.2 kg, total magnetic flux 72,000 maxwell, total magnetic flux 15,500 gauss.
The air chamber in which the center pole is tapered and hollowed out suppresses unnecessary resonance behind the diaphragm and suppresses distortion at large input, and an acoustic diffuser is mounted on the front of the diaphragm to improve directivity.
A 3-cm dome type tweeter is installed in the high range.
A 30 φ mm dome-shaped beryllium diaphragm is used for the diaphragm. It is directly connected to a heat-resistant aluminum ribbon wire edgewise wound voice coil. It is supported by a tangential edge of a special fiber with double coating of viscoelastic resin and thermosetting resin. The center pole in the space behind the voice coil is tapered and the gap is filled with sound absorbing material to suppress unnecessary resonance inside the unit.
The magnetic circuit uses a ferrite magnet of 80 φ mm, weight 0.8 kg, magnetic flux density 14,500 gauss, total magnetic flux 20,000 maxwell.
The frame of each unit is made of aluminum die-cast.
The network section uses an MP capacitor and is designed based on electrical characteristics and audibility check.
Also, the Mid-high and Tweeter are equipped with continuously variable level control.
The enclosure is completely sealed with an oak finish on the surface and a black finish on the baffle plate only.
The entire surface is made of the same particle board, and each surface is bonded with strong adhesive to form an integrated structure. The baffle plate and back plate are 25 mm thick, the other is 188 mm thick, and each part is reinforced.
Model Rating
| Method | 4-Way, 4-Speaker, Airtight Type, Bookshelf Type |
| Units Used | For low band : 30 cm cone type For middle and low band : 12 cm cone type For Middle and High Areas : 5 cm Dome Type For High Pass : 3 cm Dome Type |
| Playback frequency band | 40 Hz to 20 kHz |
| Lowest resonance frequency | 40Hz |
| Crossover frequency | 600 Hz, 2 kHz, 6 kHz |
| Output sound pressure level | 92dB/W/m |
| Impedance | 8 Ω |
| Maximum allowable input | 80W |
| External dimensions | Width 375x Height 745x Depth 317 mm |
| Weight | 31kg |