SONY STR-7055
¥ 79,800 (released in 1973)
Commentary
A full-fledged FM/AM stereo receiver developed based on the same design concept as the ES Series as a receiver that can be considered as a premain.
The front end of the tuner section uses a high-performance linear frequency varicon and newly developed junction FET for a high-frequency amplifier circuit.
In addition, stable local oscillation circuit and FET mixer circuit are mounted.
The IF section employs a 2-element solid-state filter and IC, and achieves sharp reception capabilities such as excellent passband characteristics and interference rejection characteristics for the same channel and adjacent channels.
The newly developed MPX IC is used in the MPX stereo separation circuit.
In addition, by using the MPX coil unit with no adjustment, it is free from deterioration of characteristics due to aging, heat and moisture.
The AM section uses a triple-tuned IFT with a high-integration IC solid-state filter.
The power amplifier section uses a differential amplifier, two power supplies directly connected to all stages, and a pure complimentary service circuit.
High-voltage low-noise ICs specially developed by our semiconductor engineers for audio applications are used in the preamp section, equalizer and flat amplifier.
These ICs, combined with a differential amplifier circuit and a pure complimentary service circuit, realize excellent linearity and distortion factor characteristics.
The power amplifier section uses a speaker protection circuit.
In addition, it is equipped with a circuit breaker to protect the power amplifier circuit. When an excessive current flows due to poor connection, etc., the circuit operates in advance so that the speaker or amplifier will not be damaged.
The tone control circuit uses an NFB-type tone control circuit with simple characteristics and low distortion and is designed to work smoothly without losing the naturalness of the mid-range.
Center 0 tuning meter is used.
Uses a muting circuit with FET switches.
Built-in high-blend circuit linked with High and Both filter switches.
Effective for stereo reception in weak electrolysis.
Since there are two types of tape input, two decks can be connected, and two devices can record simultaneously.
Equipped with a tape-to-tape mechanism that enables tape copying from deck to deck without changing the connection between 1 → 2 and 2 → 1.
It is equipped with a loudness switch.
It uses a four position, active-type filter circuit from High-OFF (flat) to Low-Both (bandpass).
It is effective for noise such as scratch noise and ground noise.
The power input mode can be changed by the mode switch.
Equipped with headphone output terminal.
Tape Monitor 1 takes precedence over Tape Monitor 2, and Tape1 can be monitored with one touch during monitoring of Tape2.
Equipped with a change-over switch that can be used for Route 3 speaker system.
It can be used in 5 ways such as A, B, C, A + B, and A + C.
Pre-power and power can be separated.
.JPG)
Model Rating
| Type | All-silicon transistor FM/AM stereo receiver | ||||||||
| Circuit system | Power amplifier 2 power supply Direct coupling pure complimentary service SEPP circuit |
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| FM Tuner Section | |||||||||
| Receiving frequency | 76 MHz to 90 MHz | ||||||||
| Sensitivity | 2 μ V (IHF) 1.6 μ V (S/N : 30 dB) |
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| S/N | 70dB | ||||||||
| Capture ratio | 1.0dB | ||||||||
| Selectivity | 70dB(IHF) | ||||||||
| Image interference ratio | 70dB | ||||||||
| Intermediate frequency interference ratio | 100dB | ||||||||
| Spurious interference ratio | 90dB | ||||||||
| AM suppression ratio | 56dB | ||||||||
| Frequency characteristic | 20 Hz to 15 kHz, ± 1 dB | ||||||||
| Distortion factor | Mono : 0.2% (400 Hz, 100% modulation) Stereo : 0.5% (400 Hz, 100% modulation) |
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| Separation | 38 dB or More (400 Hz) | ||||||||
| Antenna terminal | 300 Ω Balanced Type 75 Ω Unbalanced Type |
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| <AM Tuner Section> | |||||||||
| Receiving frequency | 530 kHz to 1605 kHz | ||||||||
| Intermediate frequency | 455kHz | ||||||||
| Sensitivity | 53dB/m (when bar antenna is used) 30 μ V (when external antenna is used) |
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| S/N | 50dB | ||||||||
| Image interference ratio | 50dB(1000kHz) | ||||||||
| IF interference ratio | 40dB(1000kHz) | ||||||||
| Distortion factor | 0.8% | ||||||||
| Antenna | Ferrite bar antenna With External Terminal |
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| Power Amplifier Unit | |||||||||
| Output |
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| Harmonic distortion factor | 0.2% or Less (Rated Output) 0.1% or Less (at 1W Output) |
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| Cross modulation distortion factor (60Hz:7kHz=4:1) |
0.2% or Less (Rated Output) 0.1% or Less (at 1W Output) |
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| Frequency response (at 1W output) | 10 Hz to 100 kHz, + 0 -1dB | ||||||||
| Input Sensitivity / Impedance | 1V/50k Ω (at Rated Output) | ||||||||
| Signal-to-noise ratio | 100 dB or more | ||||||||
| Damping factor | 50 or More (1 kHz, 8 Ω) | ||||||||
| Preamplifier Section | |||||||||
| Input Sensitivity / Impedance | Phono : 2mV/50k Ω Aux, Tape1, 2, REC/PB (Input) : 150mV/50k Ω |
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| Signal-to-noise ratio | Phono : 70 dB or more (input 3 mV, B network) Aux, Tape1, 2 rec / PB (input section) : 90 dB or more (input 250 mV, A network) |
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| Output Level / Impedance | Rec Out : 250mV/10k Ω Pre Out : 1V/4.7k Ω REC/PB (Output Part) : 30mV/82k Ω |
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| Frequency characteristic | Phono : RIAA curve ± 1 dB Aux, Tape, REC/PB (Input) : 10 Hz ~ 70 kHz, + 0 -3dB |
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| Tone control | Bass : 100 Hz, ± 10 dB Treble : 10 kHz, ± 10 dB |
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| Filter | Low Filter : 50 Hz, 12dB/oct. High Filter : 9 kHz, 12dB/oct. |
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| <General> | |||||||||
| Semiconductor used | Transistor : 49 IC:5 Diode : 29 |
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| Pwer | 100 VAC, 50Hz/60Hz | ||||||||
| Power outlet | 300W, non-interlocked : 1 system | ||||||||
| Power consumption | 120W | ||||||||
| External dimensions | Width 471x Height 157x Depth 375 mm | ||||||||
| Weight | 15.3 kg, 18.6 kg (including packaging) | ||||||||