SONY TA-F7B
¥ 178,000 (around 1977)
Commentary
A top-of-the-class DC pre-main amplifier with fully developed basic configuration and V-FET.
A DC amplifier configuration is used from the preamp section to the power amplifier section to ensure accurate amplification up to the DC range and prevent phase rotation in the low frequency range.
To make the best use of this DC amplifier, the Phono input and all input capacitors are eliminated in the direct coupling method.
The first stage of the power amplifier is a cascode-connected differential amplifier using dual FETs, and the output is taken out by a current mirror circuit. The power amplifier stage employs a cascode-connected parallel push-pull / pure complimentary service SEPP-OCL circuit for a group of V-FETs with excellent pulse response and high-frequency transistors connected to a cascode-connected parallel push-pull / pure output SEPP-OCL circuit to maximize the V-FETs.
The power supply uses a 3-transformer system in which the power supply for each block is independent.
In order to avoid interference between the left and right channels, the power supply for the power amplifier stage uses a toroidal transformer exclusively for the left and right channels.
In addition, dedicated transformers are used for the Class A power amplifier stage and the preamplifier section. Four smoothing capacitors of 15,000 μ F are used for both channels for a total of 60,000 μ F. The use of an FET buffer power supply further reduces crosstalk.
The Phono input is directly coupled to a current mirror differential amplifier with dual FET.
In addition to the RIAA feedback circuit, the NF circuit employs a DC feedback circuit using an FET to stabilize the operating point.
The flat amplifier is a 2-stage direct-coupled DC amplifier with first stage FET differential amplification of direct coupling input.
Equipped with CR type tone control capable of switching the turnover frequency.
The tone amplifier is a direct coupling input first stage FET2-stage direct connection circuit.
A relay is used for changing the phono input and the speaker.
The volume control is a 32-step detent type.
.JPG)
Model Rating
| Type | Pre-main amplifier | ||||
| Effective output (both channels, 8 Ω) | 80W+80W(1kHz) 70W + 70W (20 Hz to 20 kHz) |
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| Output Bandwidth (IHF, 8 ω) | 5 Hz to 40 kHz | ||||
| Harmonic distortion factor | 0.015% or Less (20 Hz to 20 kHz, Effective Output) | ||||
| Cross modulation distortion factor (at effective output) | Not more than 0.015% | ||||
| Damping factor | 60 or More (1 kHz, 8 Ω) | ||||
| Phono input sensitivity | 2.5 mv (2 systems) | ||||
| Phono maximum allowable input (1 kHz) | 250mV | ||||
| Tone control |
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| Filter | Low : 12dB/oct. (30 Hz or less) High : 12dB/oct. (9 kHz or higher) |
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| Power consumption | 192W | ||||
| External dimensions | Width 430x Height 170x Depth 420 mm | ||||
| Weight | 20kg |