SONY TA-F555ESR
¥ 128,000 (released in 1988)
Commentary
This pre-main amplifier is based on the TA-F555ESXII and has been further tuned up to enhance its perfection.
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-F555ESR is based on a G-chassis that is acoustically well tuned and has a 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. The heat sink is made of a large aluminum extruding that is as thick as 20 mm near the power transistor mounting area.
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-F555ESR is equipped with an A-class electrolytic capacitor of 24,000 μ F in total and a power capacitor of 72,000 μ F. The transformer is a large-capacity type that takes into consideration the balance with the capacitor. The magnetic shield case is firmly fixed by compound filling to suppress vibration.
The electrolytic capacitors that make up the rectifier circuit are made with thorough anti-vibration measures, such as suppressing the squeal of foils, and have been carefully examined in terms of sound quality. In addition, the electrolytic capacitors are tightened with an integrated vibration proof platform and resin band to eliminate vibration.
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 MC cartridges has excellent high-frequency response characteristics and employs a low-noise Hi gmFET to eliminate TIM distortion. It is also equipped with a 3-position cartridge load selector of MM/MC40 Ω / MC3 Ω for various cartridges.
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.
Remote-type rotary switches are used for the Input selector and Rec out selector to reduce the amount of wiring caused by wires.
Equipped with an adapter terminal that is convenient for connecting a graphic equalizer, etc.
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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 load) |
| Harmonic distortion factor | 0.002% or Less (8 Ω Load at 10W Output) |
| Cross modulation distortion factor | 0.004% or Less (at Rated Output, 8 Ω Load, 60 Hz : 7 khz = 4 : 1) |
| Slew rate | 125 V / μ sec 250 V / μ sec (inside) |
| Damping factor | 100 (1 kHz, 8 Ω Load) |
| Frequency characteristic | Phono MM : RIAA curve ± 0.2 dB CD, Tuner, Tape, Adaptor, Direct : 2 hz to 200 khz + 0 to 3 db |
| Signal-to-noise ratio | Phono MM:87dB Phono MC:70dB CD, Tuner, Tape, Adaptor, Direct : 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 CD, Tuner, Tape, Adaptor, Direct : 150mV/50k Ω |
| Output Level / Impedance | Rec out : 150mV/1k Ω Speaker : Applicable impedance 4 Ω ~ 16 Ω Headphone : 25mW/8 Ω |
| Tone control | Bass : + 4 -3.5 dB (100 Hz, 200 Hz turnover frequency) + 6-5dB (100 Hz, 400 Hz turnover frequency) Treble : + 7-8 dB (10 kHz, 3 kHz turnover frequency) + 4 -5dB (10 kHz, 5 kHz turnover frequency) |
| Subsonic filter | 15 Hz or less, 6dB/oct. |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 300W |
| External dimensions | Width 470x Height 170x Depth 435 mm Side Wood Removal : Width 430 mm |
| Weight | 24.5kg |