Audio Database

SB-RX70
Commentary

A speaker system employing a planar coaxial unit.

The unit is equipped with a 2-way coaxial speaker unit incorporating a 24 cm planar diaphragm woofer and a 2.7 cm planar diaphragm tweeter.
In this unit, the sound source center of each unit is aligned not only horizontally and vertically but also in the front-back direction by adopting the plane coaxial configuration. Thus, the directional characteristics of the speaker are equal in all directions, and there is almost no phase disturbance caused by the position shift between units, and the reproducibility of spatial and temporal information of the input source is improved.

Pure Mica with a sound speed of 6700m/s and a specific gravity of 1.9 is used as the skin material for the diaphragm of the woofer section, achieving a piston motion band of over 4 kHz.
The magnetic circuit uses a φ 145 mm strontium ferrite for the main magnet and a φ 120 mm barium ferrite for the cancel magnet to achieve both improved force factor and low magnetic leakage. In addition, the center pole is T-shaped, a copper cap is attached, and a copper ring is attached to the inner circumference of the magnet to reduce distortion thoroughly.
A large diameter voice coil with a diameter of 60 mm is used for the voice coil, and heat-resistant material is used for the coil itself to realize high input resistance design.
In addition, in order to achieve the quietness of the system, the newly developed rubber edge with excellent linearity and extremely low noise generated by the material itself is adopted.

The vibration plate of the tweeter has a sandwich structure that uses pure mica for the core material and diamond coated mica for the skin material. By coating diamond with the plasma CVD method on the lightweight and high-rigidity pure mica, the bending rigidity is improved by 60% and the internal loss is improved by 50%. This achieves the high-pass limit of 50 kHz (-16dB), which is far higher than the audio band.
A neodymium magnet with a maximum energy product of 31 mgo is used for the magnetic circuit. In addition, a magnetic fluid is filled in the magnetic gap and a heat radiation plate is provided in the field part to realize excellent power linearity and high input resistance.
In addition, no equalizer or protective net is provided on the front of the diaphragm, which causes unwanted reflections or inherent squeal. As a result, natural tone reproduction is achieved.

The SB-RX70 uses a unique silent technology to minimize unwanted sound levels and clarify the location of sound sources.
When the voice coil vibrates, part of the vibration is transmitted to the frame through the field part and radiated to the outside as harmful sound. To prevent this, we have adopted a sealed frame in which the front surface of the die-cast frame is covered with rubber gasket to greatly reduce harmful sound radiation from the frame. In addition, the speaker unit is mounted from inside the enclosure and the sound radiation from the mounting screw is also suppressed.
In addition, part of the vibration generated by the voice coil is transmitted to the baffle through the frame. Since the area of the baffle plate is larger than that of the diaphragm, even if the vibration level is small, the sound pressure level even if the vibration level is small. Furthermore, this sound is often resonant because the phase rotation of the sound is strong, and the quality of the reproduced sound is reduced. To prevent this, the range of vibration transmitted is limited by a separate baffle plate that separates the baffle plate, and unnecessary radiation is greatly reduced by attaching viscoelastic material to the surface.

Carefully selected audio parts are used for the network part.
LC-OFC Class 1 cables covered with anti-vibration coating are used for the wiring material. Large low-strain ferrite materials with high magnetic saturation point are used for the core of the choke coil. large diameter LC-OFC Class 1 cables are wound around the core and treated with anti-vibration coating. In addition, large electrolytic type capacitors for acoustic use and high-quality polyester film type capacitors are used depending on the application.
In addition, the network board is fixed to the enclosure with anti-vibration material to block unwanted acoustic feedback, the network elements are directly connected using crimping sleeve to achieve high-purity transmission, and the circuit for woofer and circuit for tweeter are arranged independently to reduce mutual interference.

The enclosure uses round baffles with curved surfaces in four directions to prevent adverse effects due to acoustic wave diffraction at the edges, and plates 30 mm thick for the front baffle and 25 mm thick for the other components, combined with cross-bridged construction to maximize the performance of the unit.
Aluminum pipe is used in the bass reflex port to suppress unnecessary vibration, and a rectifier is placed in the port opening to prevent wind noise.

Uses a large gold-plated OFC terminal capable of connecting extremely thick cables and 4 mm plugs.
It also supports bi-wiring.

There was a speaker stand SH-B70 which was designed for SB-RX70/SB-RX50 separately sold.
This stand is supported by a 4-point strut system with minimum area and minimum reflection. In addition, BMC material with high rigidity and internal loss is used for reinforcement between struts and speaker system base, and beech material is used for strut and base to suppress unnecessary vibration.

Model Rating
Method 2-way, 1-speaker, bass reflex system, bookshelf type, magnetic protection design
Units Used For all bands : 2-way coaxial type
For Low Band : 24 cm Flat Type
For High Frequency : 2.7 cm Flat Type
Playback frequency band 30 Hz to 50 kHz -16dB
Crossover frequency 2kHz
Impedance 6 Ω
Output sound pressure level 86dB/W/m
Allowable input 200W(MUSIC)
100W(DIN)
External dimensions Width 300x Height 480x Depth 280 mm
Weight 20kg
Sold separately : Speaker Stand SH-B70 (1 set of 2, ¥ 40,000)
External dimensions Width 350x Height 365x Depth 308 mm
Weight 5.5kg