SONY TA-F555ESA

Commentary

A pre-main amplifier with improved structure, material, and sound quality.

For the output stage, two pairs of power MOS FETs are used in parallel push-pull for each channel, for a total of eight power MOS FETs.
MOS FET (Field Effect Transistor) has been used mainly for circuits that handle small signals because of its excellent high-frequency characteristics and high integration capability. Also, because of its high input resistance, when used for power applications, MOS FET can be electrically separated a voltage amplification stage (A class stage) and a power amplification stage (B class stage).
In the TA-F555ESA, this device is further subjected to brush-up to improve the glossiness in the middle and high range, the elongation of high-frequency characteristics, and the sense of speed.

In order to pursue a vibration-free and resonance-free design, we have adopted a G-chassis structure.
The G chassis is made of unsaturated polyester with calcium carbonate, the main component of marble, and reinforced with glass fiber. Compared with metal, this material has higher internal loss and superior vibration damping characteristics. Moreover, it has higher strength and can be processed with high precision. The G chassis is made by molding this material into a shape that is acoustically examined, and realizes a strong chassis structure.
In addition, because of its non-magnetic and non-metallic nature, it does not generate electro-striction or eddy current induced by magnetic fields of transformers and condensers, and has succeeded in reducing sound quality degradation.
In addition, the TA-F555ESA uses a G-roof made of the same material as the G-chassis, increasing the rigidity of the body from the top.

The ES amplifier uses a G-chassis base structure that makes each part more rigid when mounted. Main parts such as printed circuit boards for audio circuits and power transformers are attached directly to the G-chassis and firmly fixed. In addition, the front chassis, terminal panel and case are attached at important points above the G-chassis so as to reinforce each other with connecting angles. This realizes a strong chassis structure and reduces sound quality degradation due to unnecessary vibration.

The heat sink uses a large extruded aluminum material with a thickness of as much as 20 mm near the power transistor mounting area.

S. T. D. power supply (Spontaneous Twin Drive) is used for the power supply part.
In this power supply circuit, the rectifying circuit to the power amplifier section is separated into the A-class stage and the power stage. By suppressing interference between the A-class stage and the power stage, sound quality is improved.

Class A and Class B capacitors are distributed, and the Class B capacitor is fixed with a vibration proof platform. The TA-F555ESA uses transformers selected through repeated hearings, including core materials and filler materials.

Equipped with an ES filter to prevent noise from the AC line.

High-quality parts such as mold-coated electrolytic capacitors and copper-clad small electrolytic capacitors are used.

The S. L. L. (Super Legato Linear) legato linear) method, which greatly reduces the switching distortion and crossover distortion of the output stage over a wide bandwidth.

An equalizer amplifier using a low-noise FET is mounted.

It is equipped with a direct IN jack that can be connected without going through a source direct switch or input selector.

OFC board with copper foil thickness of 70 μ m is adopted.

Gold plating is applied to all pin jack terminals and speaker terminals.

A microcomputer controlled small motor is used for the input selector.

There are 2 variations, gold and black.

Wireless remote control is included.

Model Rating

Type	Pre-main amplifier
Effective output (20 Hz to 20 kHz)	170W + 170W (4 Ω) 140W + 140W (6 Ω) 120W + 120W (8 Ω)
Output bandwidth	10 Hz to 100 kHz (60W output, 0.08% harmonic distortion rate, 8 Ω)
Harmonic distortion factor	0.001% (8 Ω at 10W output)
Cross modulation distortion factor	0.004% (at rated output, 8 Ω, 60 hz : 7 khz = 4 : 1)
Frequency characteristic	Phono MM : RIAA curve ± 0.2 dB Line system : 2 Hz ~ 200 kHz + 0 -3dB
Signal-to-noise ratio	Phono MM:87dB Phono MC:70dB Line system : 105 dB
Input Sensitivity / Impedance	Phono MM : 2.5mV/50k Ω Phono MC (40 Ω) : 170 μ V/1k Ω Phono MC (3 Ω) : 170 μ V/100 Ω Line system : 150mV/20k Ω
Output Level / Impedance	Rec out : 150mV/1k Ω Headphone : 25mW/8 Ω
Tone control	Bass : ± 7 dB (100 Hz) Treble : ± 6 dB at 10 kHz
Subsonic filter	15 Hz or less, 6dB/oct.
Suitable speaker impedance	4 Ω ~ 16 Ω
Pwer	100 VAC, 50Hz/60Hz
Power consumption	300W
External dimensions	Width 470x Height 175x Depth 435 mm Width with sidewood removed : 430 mm
Weight	24.6kg
Attachment	Wireless Remote Control RM-J350