KENWOOD LS-990D
¥ 59,800 (1 unit, released in 1986)
Commentary
A speaker system developed using Kenwood technologies such as plasma diamond diaphragm and DSD.
A 33 cm cone type woofer is installed in the low range.
The diaphragm uses New HR Carbon, in which the carbon binder is reinforced by three dimensional cross-linking to increase the rigidity. The drive section uses a large strontium magnet and a 4-layer voice coil with high linear moment.
In addition, Kenwood's original Class A suspension with two suspensions achieves more accurate diaphragm motion.
The middle area is equipped with a 10 cm semi-dome type squaker that adopts the DSD system.
In the DSD system, by integrating the voice coil bobbin and dome part, vibration is directly transmitted to the dome, enabling more faithful operation to the input signal.
In addition, plasma diamond diaphragm has high thermal conductivity and prevents temperature rise of voice coil.
In addition, the magnetic circuit employs a magnet with a total flux of 61000 maxwell and a thermosetting fusion wire voice coil. Moreover, the linearity at small amplitude is greatly improved by the adoption of Class A suspension.
A 2.5 cm dome type tweeter is installed in the high range.
This unit employs a diaphragm made of plasma diamond, a composite material in which diamond is ion-plated on the surface of titanium. This diaphragm takes advantage of the physical properties of diamond such as hardness, Young's modulus, propagation velocity, and thermal conductivity.
In addition, the structure in which the voice coil is wound directly on the vibration plate of the tweeter utilizes the good thermal conductivity of diamond to dissipate heat, and driving is done without having the voice coil absorb heat.
In addition, due to the structure of the dome diaphragm integrated up to the edge and direct inner Class A suspension, there is no unnecessary radiation from the edge or transmission loss between the voice coil and dome, and excellent transient and directional characteristics are obtained.
A floating network is used to prevent the network from vibrating due to the vibration of the enclosure, which causes the coil to cross the magnetic flux of the speaker unit and generates induced electric power, resulting in sound quality degradation.
This uses springs to attach the network to reduce vibration and adverse effects.
In addition, a separate network using Ritz pattern printed circuit boards is used.
The enclosure has round baffles rounded on both sides to reduce diffraction effects and reduce distortion due to sound interference.
Model Rating
| Method | 3-Way, 3-Speaker, Bass reflex system, Bookshelf 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 | 200(EIAJ) |
| Impedance | 6 Ω |
| Output sound pressure level | 92dB/W/m |
| Crossover frequency | 600 Hz, 5 kHz |
| External dimensions | Width 382x Height 671x Depth 345 mm |
| Weight | 23.5kg |