SONY SS-RX7
¥ 59,000 (1 unit, released in 1982)
Commentary
A bookshelf type speaker system that employs a POM (polyoxymethylene) whisker diaphragm.
A 30 cm cone type woofer is installed in the low range.
This diaphragm uses a cone paper shape determined through analysis and hearing using NASTRAN, a vibration analysis method for spacecraft. It is made of a material that provides a warm low sound compared to cone paper. It also uses a urethane edge with excellent response and a high linearity damper to enable stable diaphragm operation.
For the magnetic circuit, we have introduced techniques such as a T-shaped pole piece with symmetrical magnetic flux distribution in front and back, and a perforated yoke that reduces the back pressure of cone paper to reduce distortion.
Solid aluminum die-cast frame is used for the frame.
The mid-range is equipped with 10 cm cone type mid-range using POM whisker.
POM whiskers are shaped like a sea urchin, with approximately 10 to several hundred needle-shaped single crystals of 1 to 3 microns in thickness and around 150 microns at the longest protruding from the center in all directions. They are lighter than carbon fibers (specific gravity of 1.49, carbon fibers are approximately 1.7). They are dispersed very uniformly in resin, and have good wettability and adhesion. Furthermore, they have a high elastic modulus and sound velocity of 9000m per second, which is approximately 1.8 times that of aluminum or titanium. By combining POM whiskers with polyolefin resin mainly composed of polypropylene, vibration plates with high rigidity and light mass in addition to large internal loss have been realized.
In addition, strontium ferrite magnets are used for the magnetic circuit, and aluminum die-cast is used for the frame.
A 2.5 cm soft dome type tweeter is installed in the high range.
A flexible special film is used for the diaphragm, and the edge and dome are integrally molded to reduce distortion.
This unit also uses strontium ferrite magnets and aluminum die-cast frames as in the mid-range.
In the network section, oxygen-free copper wires are used for electrolytic capacitors in plastic cases, coils and internal wiring materials to reduce distortion and loss.
The enclosure uses high-density particleboard for all board materials to reduce unnecessary vibration.
In addition, fine grooves are provided on the inner periphery of the baffle plate and the back plate to control the vibration frequency of each plate including the body plate, thereby obtaining a sound with a good ear feeling.
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Model Rating
| Method | 3-Way, 3-Speaker, Bass reflex system, Bookshelf Type |
| Unit | For low band : 30 cm cone type For Medium Range : 10 cm Cone Type For high-pass : 2.5 cm dome type |
| Playback frequency band | 30 Hz to 25000 Hz |
| Output sound pressure level | 93dB/W/m |
| Impedance | 6 Ω |
| Instantaneous maximum input | 200W |
| Rated maximum input | 100W |
| Crossover frequency | 900 Hz, 4 kHz |
| Internal volume | 55L |
| External dimensions | Width 370x Height 660x Depth 350 mm |
| Weight | 19.5kg |
| Attachment | Speaker Cord (3m) |