DBX SF-One(Soundfield One)
¥ 848,000 (1 set of 2, released in 1984)
Commentary
A floor-type speaker system with a sound field control function.
The SF-ONE consists of a speaker system SF-X 1 and a sound field controller SFC-1.
When listening to the sound of a stereo system, the listener hears not only the direct sound coming from the speakers but also the reflected sound coming from all directions at the same time. The sound field for stereo reproduction is composed of components such as direction, volume, phase, and delay of the reflected sound.
SF-ONE pursues a rich musical sense of reality through sound field control that combines the direction, quantity, and delay degree of direct and indirect waves to optimize them. Under the guidance of Dr. Mark F. Davis, an American acoustic psychologist, it was developed by pursuing the ideal radiation pattern of speakers that determine sound field control.
In order to realize a speaker with an ideal radiation pattern, we have adopted the time versus intensity exchange effect, which is an acoustopsychological phenomenon. This effect compensates for the left-to-right bias on arrival by adding a reverse bias to the amplitude. We conclude that the speaker has directivity and must emit sound more strongly in one direction than in the other. To determine the radiation pattern with the appropriate time versus intensity exchange, we repeat the hearing test to obtain a correlation diagram of amplitude versus angle that gives the optimum sound localization. This enables us to analyze the radiation pattern of sound pressure contours using computer graphics.
In addition, sound reflected by walls etc. is used as an acoustic delay to maintain ideal sound image fusion, and a fully horizontal radiation pattern is established by setting a backward radiation pattern with a forward horizontal radiation pattern as a mirror object.
The vertical radiation pattern is set so that the sound quality does not change significantly regardless of the position of the listener, and the sound emitted above the speaker is sufficiently limited.
Fourteen speaker units are used to achieve an ideal radiation pattern.
Four 10-inch cone woofers for the low range and four 4 1 / 2-inch cone midrange woofers for the middle range, mounted on each of the four sides of the floor cabinet.
In addition, 6 1/2inch domed tweeters are mounted on the upper hexagonal surface for high frequency.
The four sided woofer and mid-range speakers have the same characteristics on the front and rear sides and different characteristics on the inside and outside sides. These units have three characteristics in total. The six tweeters combine four types of speakers : the inside and outside sides, two inside oblique sides, and two outside oblique sides. Each speaker has a different crossover frequency, frequency characteristics, and volume.
The volume is set to the maximum on the inner side (facing side) for all bands, and then the strength is adjusted on both front and rear sides, and then on the outer side.
The LF/MF crossover frequency is 450 Hz and the MF/HF crossover frequency is 3.15 kHz.
The crossover design is a computer-driven design that not only matches the characteristics of each driver individually to provide the optimum sound field radiation pattern, but also maintains a constant input impedance throughout the entire drive, enabling the handling of power amplifiers with excellent power response.
Dedicated controller SFC-1 is attached.
In addition to the equalization function that ensures the overall characteristics of the SF-ONE, the SFC-1 is equipped with an ambience adjustment that controls the subtle nuances of the sound field, a unique Low/High compensation function, a power monitor circuit for speaker protection, and an auto-balance function.
.jpg)
.jpg)
.jpg)
.jpg)
Model Rating
| Speaker System SF-X 1 | |
| Method | 3-Way, 14-Speaker, Sealed Type, Floor Type |
| Units Used | * Refer to the unit configuration below. |
| Frequency characteristic | 20 Hz to 20 kHz ± 1.5 dB |
| Delay (typical group, 60 ° off for sound axis) |
± 0.2 ms (500 Hz to 20 kHz) ± 2 ms (100 Hz to 500 Hz) (100 Hz or less When an infrasonic filter is used |
| Efficiency (middle range) | 90dB SPL 2.83V/m |
| Recommended power | 50W ~ 500W/ch |
| Impedance | 4.5 Ω ± 1.5 Ω (0 ° ± 20 °) 3 Ω (20 kHz), 6 Ω (3 kHz) |
| Output sound pressure level | 90dB/W/m (8 Ω conversion) |
| External dimensions | Width 368x Height 1,066x Depth 368 mm |
| Weight | Approx. 33 kg |
| Unit Configuration | |
| Woofer unit | |
| Voice coil diameter | 19mm |
| Nominal bore | 25 cm (Circumference Diameter 23 cm, Effective Diameter 19 cm) |
| fo | 30 Hz ± 5 Hz (free air) |
| Magnetic circuit | Ferrite magnet |
| Weight | 1500g |
| Mid-range unit | |
| Nominal bore | 13 cm (Circumference Diameter 10.5 cm, Effective Diameter 8.5 cm) |
| fo | 320 Hz ± 50 Hz |
| Magnetic circuit | Ferrite magnet |
| Total flux | 33,700maxwell |
| Magnetic flux density | 9,100gauss |
| Weight | 830g |
| Tweeter unit | |
| 5 Units | 1.25 cm Dome Type Alnico magnet |
| 1 Unit | Inside diameter 1.25 cm Edgeless compound diaphragm 15g Strontium ferrite magnet |
| <Dedicated Control Unit SFC-1> | |
| Total harmonic distortion factor | 0.05% |
| Intermodulation Distortion Factor (IMD) | 0.1%(SMPTE) 0.1%(IHF) |
| Dynamic range | 106dB |
| Max Input | 3.1 V (4.2 V at 32 Hz ~ 15 kHz) |
| Maximum power output | 5.3V |
| Maximum gain | +5.1dB(20Hz) |
| Minimum gain | -17dB(1kHz) |
| Input impedance | 50k Ω |
| Output impedance | 470 Ω Tape terminal : 220 Ω |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Power consumption | 12W |
| External dimensions | Width 455x Height 44x Depth 190 mm |