SONY TA-F777ES

Commentary

This is a pre-main amplifier of the high-end model of the ES series that goes through not only the circuit technology but also the construction and every part including the fine details due to the philosophy of simple and straight music signal.

An audio current transfer system has been adopted to improve the characteristics of four amplifiers (preamp, power amplifier, L and R).
In this method, a current conversion amplifier is inserted between the preamp section and the power amplifier section. The output of the preamp section, which comes out as a voltage signal, is first converted into a current signal, and then converted back into a voltage signal by a linear gain control attenuator installed at the final stage of the current conversion amplifier.
Therefore, the preamplifier section has infinite impedance as seen from the power amplifier, and is completely electrically isolated.
As a result, it is possible to pursue the characteristics of each of the four amplifier sections independently. In addition, it is possible to ignore the noise pollution factors such as the contact resistance of the switch and connector and the intrinsic impedance of the wire.
In addition, by adopting the linear gain control type attenuator, which can be used in the audio current transfer system, as the volume for volume adjustment, the impedance decreases as the gain is reduced. As a result, various characteristics at the volume position in actual use are improved.

The power supply for the preamp section uses a constant current shunt regulator to eliminate the influence of the power amplifier power supply and to ensure stable regulation.

A high-speed output element Hi-f is provided in the power amplifier section without shifting bias or changing the power supply voltage._TIt employs a Leger-Linear system in which the transistor operates in a very small cutoff region.
In addition, the 4-para push configuration reduces dynamic distortion such as switching distortion and crossover distortion over a wide band. In addition, it is equipped with a powerful power supply part of 2 power transformer, 6 winding, 7 power supply.

A DC amplifier system is used to prevent the negative effect of the signal capacitor on sound quality.
To stabilize the operation of the DC amplifier and section to stabilize the operation of the DC amplifier and obtain a rich low frequency range.
In order to eliminate thermal modulation distortion of the circuit and element, a constant PC circuit was adopted in the differential section of the equalizer amplifier and the first stage of the power amplifier to improve the resolution in the audible band.

LC-OFC is used for wiring materials, printed circuit boards, power cords, etc.
We also use a large number of carefully selected components such as high-capacity capacitors, copper-plated chassis to eliminate magnetostriction, and large heat sinks with high heat dissipation.

The core material is an amorphous alloy, and a booster transformer for MC cartridge is built in with special filling process.
In addition, a 2-position cartridge selector of 330pF/100pF for MM and 40 Ω / 3 Ω for MC is mounted.

Equipped with Direct/On switchable tone control.

Model Rating

Type	Stereo pre-main amplifier
Rated output	180W + 180W (20 Hz to 20 kHz, 0.004%, 4 Ω)
Harmonic distortion factor	0.004% (20 Hz ~ 20000 Hz, Rated Output)
Signal-to-noise ratio	Phono MM:82dB Phono MC:74dB
Dynamic range	120dB
Pwer	100 VAC, 50Hz/60Hz
Power consumption	300W
External dimensions	Width 430x Height 155x Depth 450 mm
Weight	19.0kg