OPTONICA CP-R3
¥ 29,800 (1 unit, around 1975)
Commentary
Ribbon type tweeter capable of high-frequency playback.
A ribbon type drive system is adopted.
In the ribbon type, the voice coil itself is used as a diaphragm, and the signal current vibrates the ribbon itself, making efficient piston motion possible. The ribbon can be reproduced up to a high sound range far exceeding the audible range.
In addition, by using high-purity hard aluminum foil (8 microns thick) for the material of the ribbon diaphragm, a light weight of 10 mg has been achieved, and excellent high-frequency and transient characteristics have been obtained.
Since the diaphragm is a linear sound source with a length of 58 mm and a width of 7.5 mm, directional characteristics are also improved.
The ribbon tweeter has an extremely low value of 0.05 Ω because the aluminum foil diaphragm itself becomes a load impedance. Moreover, since a large current of about 10A instantaneously flows through the aluminum foil diaphragm, a matching transformer with low loss, low distortion, and wide band is required.
In the CP-R3, a ferrite core with good high-frequency characteristics is used for the transformer core, and a sandwich winding is used for the primary winding and a low-loss winding is used for the secondary winding.
Built-in 5 kHz high-pass network circuitry for direct connection to speaker systems using low-loss metalized polyester film capacitors.
Built-in 30 kHz filter for tweeter protection.
When a CD-4 record is reproduced at high output using a wide-band cartridge capable of reproducing at 20 kHz or higher, the CD-4 carrier (30 kHz) signal may be continuously applied to the tweeter causing the diaphragm to be blown. The protective filter switch protects the tweeter from these problems.
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Model Rating
| Type | Ribbon type tweeter |
| Frequency characteristic | 5 kHz to 50 kHz |
| Network | 5 kHz, -12dB/oct high-pass filter |
| Maximum allowable input | 63W(MPO) |
| Sound pressure level | 91dB/W/m |
| Total flux | 115,000maxwell |
| Magnetic flux density | 4,300gauss |
| External dimensions | Width 123x Height 96x Depth 138.5 mm |
| Weight | 1.8kg |