SONY SS-7220A
¥ 40,000 (1 unit, around 1974)
Commentary
This is a bookshelf speaker system that uses Sony's unique low-distortion magnetic circuit.
Sony's unique low-distortion magnetic circuit reduces non-linear distortion due to magnetic materials through two modifications : a notch in the center of the center pole and a thick copper plating or copper cap.
In cone speakers, abnormal sound is radiated at an extremely large level in a band 2 to 3 times the upper limit frequency due to abnormal vibration of the voice coil bobbin, bobbin and cone joint, etc. Therefore, we use a dust-proof cap with excellent sound insulation characteristics to prevent abnormal sound radiation.
It has a 25 cm cone woofer in the low range and a 10 cm cone midrange in the middle range.
The diaphragm uses carefully selected Northern European pulp to suppress the turbidity of the sound generated by divided vibration.
A 2.5 cm dome type tweeter is installed in the high range.
The network section uses a large air-core coil that has little DC resistance and is not distorted by large input.
The mid-range and high-range are equipped with continuously variable level control that can be adjusted according to the sound characteristics of the room.
The enclosure uses 20 mm thick hard particleboards.
Model Rating
| Method | 3-Way, 3-Speaker, Bass reflex system, Bookshelf Type |
| Unit | For low band : 25 cm cone type For Medium Range : 10 cm Cone Type For high-pass : 2.5 cm dome type |
| Effective frequency band | 40 Hz to 20 kHz |
| Output sound pressure level | 88dB/W/m |
| Impedance | 6 Ω |
| Maximum allowable input | 70W(Weighted pink noise) |
| Crossover frequency | 600 Hz, 4.5 kHz |
| External dimensions | Width 350x Height 590x Depth 290 mm |
| Weight | 15kg |