KENWOOD LS-990AD
¥ 59,800 (1 unit, around 1986)
Commentary
This speaker system inherits the LS series technology and uses a plasma diamond vibrating plate.
33 cm new HR carbon cone type woofer is used for the low range.
The binder of the carbon part is further strengthened by three dimensional cross-linking, and the synthesis is improved, and a crisp low sound is realized.
In addition, a large strontium magnet and a 4-layer voice coil are used for the drive part.
A 10 cm semi-dome type squaker is used for the middle area.
The cone section has a three layer sandwich structure in which high elasticity reinforced fibers are ion-plated with aluminum, molded with a reinforcing binder, and backed with a pulp layer. The cone section is highly rigid and reduces the noise inherent in the material. In addition, the dome section uses the same plasma diamond vibrating plate as the tweeter.
The magnetic circuit uses a 61000 maxwell magnet with a total magnetic flux and a voice coil with heat-curable fusion-bonding wire.
A 2.5 cm hard dome type tweeter with a plasma diamond vibrating plate is adopted for the high frequency range.
This vibration plate is made of a composite material in which a thin film of diamond is ion-plated on a titanium base material. It is an excellent vibration plate with high rigidity, no resonance point, and light weight.
In addition, the coil is wound around the surface of the diamond to diffuse heat taking advantage of the good thermal conductivity of the diamond, so that the voice coil does not have heat.
In addition, it adopts a structure consisting of a dome vibration plate integrated up to the edge and a direct inner Class A suspension, and features such as no transmission loss because the voice coil and dome are integrated, no additional mass is applied to the vibration system because no adhesive is used to attach the edge, and no unnecessary radiation of the edge.
Class A suspension is used for all of woofer, skoker and tweeter.
The network is a separate network with separate boards for woofer, skorker, and tweeter to minimize mutual interference.
In addition, the LS 990 ad focuses on crosstalk between the unit and the network, and the s-etch method of the network has been drastically changed. In addition, a clean ground line that independently supplies the ground for the network circuit and the ground for the speaker unit has been adopted so that a cleaner signal flows to the unit.
The level control uses an acoustic level control and can be adjusted according to the setting conditions.
Model Rating
| Method | 3-Way, 3-Speaker, Basref System, Bookshelf Type, Magnetic Shielding Type |
| Unit | For low band : 33 cm cone type For Middle Area : 10 cm Semi-dome Type For high-pass : 2.5 cm dome type |
| Playback frequency band | 28 Hz to 47 kHz |
| Max Input | 200W(EIAJ) |
| Impedance | 6 Ω |
| Output sound pressure level | 92dB/W/m |
| Crossover frequency | 600 Hz, 5 kHz |
| External dimensions | Width 355x Height 671x Depth 321 mm |
| Weight | 22kg |