OPTONICA CP-4500
¥ 65,000 (1 unit, around 1975)
Commentary
A bookshelf type speaker system that uses a New B & B diaphragm.
A 30 cm cone type woofer is installed in the low range.
New B & B Cone is used for the diaphragm. This diaphragm is based on B & B Cone, which is made by specially treated Japanese paper mixed with Scandinavian pulp. It has undergone alkali beating and neutral sizing treatment to realize stronger cone. In addition, the porous dust cap prevents non-linear distortion and the opening is reinforced and molded to prevent abnormal vibration.
In addition, the magnetic circuit with a copper cap suppresses second and third harmonic distortion, and the long voice coil with a winding width approximately 2.5 times the plate thickness suppresses distortion at large amplitude.
By adopting an aluminum die-cast frame for the frame, resonance and vibration of the frame itself are suppressed.
A 4 cm dome type skoker is installed in the middle area.
Alumina blend dome diaphragm is used for diaphragm. Alumina fiber and pulp fiber are mixed and molded and coated with special acrylic resin to combine features of hard dome and soft dome. In addition, perforated pole and large back cavity lower fo to 260 Hz and avoid the use of band with large phase rotation to improve orientation. Aluminum voice coil improves efficiency.
By installing an equalizer on the front of the unit, the directivity and response are improved, and by using an aluminum die-cast frame for the frame, vibration is suppressed.
A 2.4 cm dome type tweeter is installed in the high range.
The diaphragm is an alumina blend dome diaphragm made of alumina fiber similar to the SCOKER diaphragm. In addition, efficiency is improved by the aluminum voice coil, and directivity and response are improved by the equalizer.
A 12dB/oct LC-type low-loss network is used in the network section.
A reactance compensation circuit is used for the woofer and squaker section, and a low loss metallized polyester film capacitor is used for the high pass circuit of the tweeter section.
The front baffle is equipped with a continuously variable level control that can be continuously changed from + 3 dB to MIN for the middle and high frequency ranges.
The enclosure is hermetically sealed. The unit is arranged in a straight line and the front baffle is an edgeless type to suppress the disturbance of sound waves reproduced from the unit and improve directivity.
In addition, by using a material with high sound absorption coefficient for the internal sound absorbing material, ideal Q characteristics are obtained, and transient characteristics and frequency response are improved.
The net is detachable.
Equipped with multi-amplifier terminal, 2-way or 3-way multi-amplifier drive is possible.
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Model Rating
| Method | 3-Way, 3-Speaker, Airtight Type, Bookshelf Type |
| Units used, etc. | For low band : 30 cm cone type For Middle Area : 4 cm Dome Type For high-pass : 2.4 cm dome type |
| Playback frequency band | 30 Hz to 20 kHz |
| Maximum allowable input | 63W(MPO) |
| Impedance | 8 Ω |
| Sound pressure level | 90dB/W |
| Crossover frequency | 550 Hz, 4.5 kHz (LC Type, 12dB/oct) |
| Level control | Continuously Variable Type for Medium Range Continuously Variable Type for High Frequency |
| Internal volume | 65L |
| External dimensions | Width 400x Height 700x Depth 339 mm |
| Weight | 27kg |