SONY TA-F555ESG

Commentary

Based on the TA-F555ESR, this pre-main amplifier is equipped with a remote controller to improve operability and some parts are reviewed to improve sound quality.

The TA-F555ESG uses an internal rotary switch to switch the input function and control the volume by driving a microcomputer controlled small motor based on commands from the remote control. This enables remote control operation without using electronic switches or electronic volumes, which can cause sound quality concerns.
In addition, the microcomputer is deactivated when no remote control operation is performed, such as during listening, to prevent the effect on sound quality.

The chassis uses an Acoustic Tuned G chassis (Acoustically Tuned Gibraltar Chassis) that pursues a vibration-free and resonance-free design from all angles including material and shape.
The G-chassis is made of calcium carbonate, the main component of marble, reinforced with unsaturated polyester and glass fiber. This material has superior vibration damping characteristics with greater internal loss than metals, and is also strong and capable of high-precision machining. In addition, this material is non-magnetic and non-metallic, so there is no electro-striction or eddy current induced by magnetic fields of transformers and condensers, etc., and from the electrical aspect, sound quality degradation is reduced.
The shape of the G chassis is designed with careful attention paid to acoustic characteristics. It has a very simple structure with no protruding parts. It eliminates partial resonance and split vibration that occur at the protruding parts. In addition, the thickness of each part of the chassis is sufficiently large, and the rigidity is increased by running ribs vertically and horizontally. In addition, the thickness of the ribs and the spacing between ribs are changed randomly so that there is no specific resonance mode.

The TA-F555ESG is based on an acoustically well-tuned G-chassis that is further stiffened as each part is mounted. Major parts such as printed circuit boards for audio circuits and power transformers are attached directly to the G-chassis and firmly fixed.
The heat sink is made of extruded aluminum with a thickness of up to 20 mm near the power transistor mount.
In addition, the front chassis, terminal panel, and case are mounted on the G chassis so that they reinforce each other with connecting angles at important points, thereby realizing a stronger chassis structure.

S. T. D. (Spontaneous Twin Drive) power supply is used for the power supply part.
In the S. T. D. power supply, the rectifier circuit of the power amplifier is separated into the A power supply for the A-class stage and the B power supply for the power stage to prevent interference between the A-class stage and the power stage at high output.
The TA-F555ESG uses a stacking type in which several small capacitors are connected in parallel inside the case rather than increasing the capacity of the electrolytic capacitor in order to make it closer to the capacitor of ideal operation. This improves the instantaneous current supply capability while reducing the coil component of the wound foil to obtain more natural sound quality. In addition, in order to further enhance the vibration resistance, the case of the capacitor and the vibration proof platform to which the capacitor is fixed are treated with velvet-like electrostatic hair transplantation.
In addition, the transformer is a large-capacity type that takes into consideration the balance with the condenser. The magnetic shield case is filled with compound and firmly solidified, and then firmly fixed to the G chassis.
In addition, it is equipped with an ES filter to prevent noise from the AC line.

The tone circuit consists of only passive elements, so the amplifier circuit is simple with only two parts, the phono equalizer and the power amplifier.

The power amplifier employs the S. L. L. (Super Legato Linear) method, which reduces the switching distortion and crossover distortion of the output stage in a wide band / wide dynamic range. This not only reduces the distortion factor at the actual output, but also improves the distortion factor at the playback level in actual use.

The phono equalizer amplifier section for the MC cartridge uses a low-noise Hi gmFET that has excellent high-frequency response characteristics and eliminates TIM distortion.

The tone circuit consists of passive elements instead of active elements, and is equipped with a TONE switch that can pass the circuit with one touch operation.

A source direct switch is provided. Pressing this switch jumps through the tone control, subsonic filter, balance, mode switch, etc. The input signal selected by the INPUT selector is output through the minimum path of the attenuator and power amplifier.
It also has a direct-in terminal that does not pass through the input selector.

Equipped with an adapter terminal that is convenient for connecting a graphic equalizer, etc.

All pin jack terminals are gold-plated in order to reduce contact resistance.

Model Rating

Type	Pre-main amplifier
Effective output (20 Hz to 20 kHz)	180W + 180W (4 Ω) 150W + 150W (6 Ω) 120W + 120W (8 Ω)
Output bandwidth	10 Hz to 100 kHz (60W output, 0.04% harmonic distortion rate, 8 Ω)
Harmonic distortion factor	0.002% (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/50k Ω
Output Level / Impedance	Rec out : 150mV/1k Ω Headphone : 25mW/8 Ω
Tone control	Bass : + 4 -3.5 dB (100 Hz, 200 Hz turnover) + 6-5 dB (100 Hz, turnover 400 Hz) Treble : + 7-8 dB (10 kHz, turnover 3 kHz) + 4-5dB (10 khz, turnover 6 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 170x Depth 435 mm Width with sidewood removed : 430 mm
Weight	24.5kg
Attachment	Wireless Remote Control RM-J350