A speaker system developed with Yamaha's original technologies such as beryllium diaphragm based on the basic idea of creating something that will be used as a reference for a long time.
It was sold for a long period of 23 years from 1974 to 1997, and was used as a monitor speaker Swedish and Finnish national broadcasting stations.
Beryllium diaphragm is used for the diaphragm in the middle and high range.
This diaphragm was successfully developed by applying the electron beam vacuum deposition method and special alloy technology used in LSI manufacturing technology with our own technological strength. Since it is manufactured in a high vacuum, it contains fewer compounds than that of the diaphragm finished with rolled plate, and achieves high purity.
In addition, it is possible to produce deep domes and tangential edges that are difficult to be produced by drawing because it is deposited after being made into atomic or plasma state.
We have also succeeded in protecting the corrosive beryllium material from harmful atmospheric constituents by applying a special coating of about 5 microns thick.
A 30 cm cone type woofer JA 3058 a is mounted in the low range.
The diaphragm is made of corrugated cone paper developed through many years of material research. The edge is made of double-coated fabric with thermosetting resin and viscoelastic resin for resonance suppression to increase linearity to the input signal.
The magnetic circuit uses a 156 φ ferrite magnet, and the voice coil is edge-wise wound with copper ribbon wire.
The middle area is equipped with JA 0801 which is a 8.8 cm dome type skoker.
It uses a beryllium diaphragm with a diaphragm diameter of 68 mm produced by Yamaha's original manufacturing method. In addition, the edge uses a double coating tangential edge impregnated with viscoelastic resin and thermosetting resin, which are the results of research in the development of soft dome type such as NS-690. Thus, sufficient shape retention and center retention capability are obtained without losing the characteristics of beryllium. In addition, the voice coil uses a large diameter of 66 φ and is wound with copper ribbon wire edgewise to increase efficiency.
This vibration system is designed so that the air pressure behind each part such as the beryllium diaphragm, voice coil and edge is the same. The rear part of the diaphragm is connected to the center pole hollowed out and is connected to the back cavity. The rear part of the voice coil is connected to the back cavity through an air hole in the bottom plate of the magnetic circuit. The rear part of the voice coil is connected to the back cavity. The rear part of the edge is connected to the air hole in the voice coil bobbin, and the outer pole is also connected to the air hole to release air at the edge.
The magnetic circuit uses a large 156 φ magnet and achieves a magnetic flux density of 16,000 gauss to improve the transient characteristics.
In order to increase the rigidity of the diaphragm and improve the directivity, a dome type with a small radius of curvature is adopted. Therefore, the valley caused by interference in the off-band on-axis characteristics is suppressed by the adoption of a diffuser, and the on-axis characteristics are extended as much as possible to improve the connection around the crossover frequency with the tweeter.
Ja 0513, a 3.0 cm dome type tweeter, is installed in the high range.
The diaphragm uses a 23 mm lightweight diaphragm weighing a weight of 0.03g or less that takes advantage of the characteristics of beryllium material. It uses a cloth tangential edge with double coating of viscoelastic resin and thermosetting resin to suppress unnecessary resonance.
Voice coil diameter is 23 mm, aluminum wire edgewise winding directly connected to beryllium diaphragm is adopted, and the entire vibration system is finished to be lightweight.
In addition, the center pole of the space behind the voice coil, which is the result of research such as the NS-690 tweeter, is tapered and irregularly shaped, and is filled with sound absorbing urethane to suppress the influence of resonance.
Method 3-Way, 3-Speaker, Airtight Type, Bookshelf Type
Units Used For Low Band : 30 cm Cone Type (JA-3058A)
For Middle Area : 8.8 cm Dome Type (JA-0801)
For High Range : 3.0 cm Dome Type (JA-0513)
Playback frequency band 40 Hz to 20 kHz
Crossover frequency 500 Hz, 6 kHz, 12dB/oct.
Lowest resonance frequency 40Hz
Impedance 8 Ω
Output sound pressure level 90dB/W/m
Rated Input (JIS Continuous) 50W
Maximum allowable input 100W
Level controller Medium / high tone, continuously variable type
External dimensions Width 375x Height 675x Depth 326 mm
Weight 31kg
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27 фев 2023
