DIATONE DA-25T
¥ 59,000 (released in 1968)
Commentary
Diatone is the first receiver released at the same time as the pre-main amplifier DA-55U.
The amplifier uses the complimentary service SEPP-OTL system with all-silicon transistors.
The power transistor is a diffused silicon transistor with high resistance to secondary breakdown. It is designed to withstand a small amount of output short-circuit even if the speaker terminal is short-circuited by mistake. In addition, an electronic switch using a silicon thyristor is a double safety measure.
When the output terminal is short-circuited, the overload is displayed and can be identified at a glance.
A silicon Planer transistor is used in the FM tuner section to increase sensitivity.
The FM multi-circuit uses a pure electronic automatic switching circuit that automatically switches between mono and stereo when receiving stereo signals. The stereo indicator lights when receiving stereo signals.
This circuit employs a balanced switching system, which, together with the CR composite element (38 khz filter), reduces the leakage of the subcarrier and enables reception with high separation and low distortion.
The AM tuner section is equipped with a ferrite bar antenna.
The tone control uses 7-step 3-dB switching tone control.
With this method, there is no deviation between channels, and accurate tone adjustment is possible.
The exterior uses a wooden cabinet made of Eurasian teak material, which is the same design as that of the commercial Diatone speaker announced at the same time.
Model Rating
| Type | Stereo Tri-Amplifier with FM (MPX) |
| Amplifier Unit | |
| Maximum power output | 49.5W + 49.5W (4 Ω) / 20% or Less |
| Continuous output | 32W + 32W (4 Ω) 30W + 30W (4 Ω, listed in separate catalog) |
| Music power | 43W + 43W (4 Ω) |
| Distortion factor | 0.5% or less (Music Power) 1% or Less (Continuous Output) 20% or less (at maximum output) |
| Frequency characteristic | 20 Hz to 20 kHz -2dB (Tape) |
| Input | Phono : 4.7mV/47k Ω Tape : 185mV/125k Ω |
| Tone control | Low frequency : + 9 dB -13dB (100 Hz in 3 dB steps) High frequency : + 10 dB -12dB (10 kHz, 3 dB step) |
| S/N | Tape : 65 dB or more |
| Damping factor | 30-60 30 (8 Ω, listed in separate catalog) |
| FM Tuner Section | |
| Receiving frequency | 76 MHz to 90 MHz |
| Antenna | 300 Ω Balanced Type |
| Sensitivity | 3 μ V/83MHz (30% modulation, S/N ratio 30 db) |
| Signal-to-noise ratio | 50 dB (input 60 dB μ V, 83 MHz, 30% modulation) |
| Frequency characteristic | 20 Hz ~ 15 kHz ± 2 dB (stereo) |
| Distortion factor | 1% or 1% (400 Hz, 30% modulation, 83 MHz) |
| Stereo separation | 40 dB or more |
| <AM Tuner Section> | |
| Receiving frequency | 535 kHz to 1605 kHz |
| Antenna | Bar Antenna with External Terminal |
| Sensitivity | 50 μ V/m (1000 kHz) |
| Signal-to-noise ratio | 40 dB (input 74 dB μ V/m, 1000 kHz, 30% modulation) |
| Frequency characteristic | 100 Hz to 4.5 kHz -2dB |
| Distortion factor | 2% or Less (400 Hz, 30% modulation, 1000 kHz) |
| <General> | |
| Transistor used | Transistor : 33 Diode : 23 Pieces Thyristor : 1 |
| Pwer | AC100V |
| Power consumption | 104VA |
| External dimensions | Width 460x Height 170x Depth 310 mm |
| Weight | 9.0kg 9.5 kg (listed in separate catalog) |
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