SONY TA-1055A

Commentary

This is a pre-main amplifier that inherits the design philosophy of the ES series, eliminates coloring, and aims to extract program source faithfully.

The power amplifier section uses a direct-coupling type differential-amplified two power supply and semi- complimentary service circuit.
In the preamplifier section, a high-voltage low-noise IC specially developed for audio is used for the equalizer amplifier to improve linearity and distortion factor characteristics.

It has a built-in PNP-NPN2-stage direct amplifier dedicated for microphone mixing, so that the appropriate level can always be set by the microphone level control.
In the case of a single microphone, if it is plugged into the left side, even in monaural, only the sound of the microphone can be transmitted from both channels.

The tone control uses a slide type and comes with a center click so that flat position can be easily obtained.

Model Rating

Type	All-silicon transistor stereo premain amplifier
Circuit system	Power Amp : Direct coupling, quasi complimentary service - Symmetric SEPP circuit Preamplifier : NF type using monolithic IC Microphone Amplifier : PNP-NPN2-stage direct connection
Output (0.1% harmonic distortion factor)	Dynamic power (IHF, constant voltage supply method) : 70W (8 Ω) 90W (4 Ω) Effective power 1 kHz, both channels (0.5% distortion) : 23W + 23W (8 Ω) 27W + 27W (4 Ω) 40 Hz to 20 kHz, both channels : 20W + 20W (8 Ω)
Output band characteristic	10 Hz ~ 40 kHz (8 Ω, IHF)
Harmonic distortion factor	0.5% or Less (Rated Output) 0.2% or Less (at 1W output)
Cross modulation distortion factor (60Hz:7kHz=4:1)	0.5% or Less (Rated Output) 0.2% or Less (at 1W output)
Damping factor	22 (1 kHz, 8 Ω)
Residual noise	0.25 μ W or less
Input Sensitivity / Impedance	Phono : 2.5mV/10k Ω MIC : 1.8mV/47k Ω Tuner, AUX, Tape1, 2, Rec/PB (input section) : 250mV/50k Ω
Maximum allowable input	Phono:70mV
Output Level / Impedance	Rec Out1, 2 : 250mV/13k Ω Rec/PB (Output Part) : 30mV/82k Ω Speaker terminal : 4 Ω ~ 16 Ω compatible
Signal-to-noise ratio	Phono : 70 dB (input 2.5 mV, B-network) MIC : 65 dB (input 1.8 mV, B network) Tuner, Tape1, 2, Rec/PB (input section) : 90 dB (input 250 mV, A network)
Frequency characteristic	Phono : RIAA curve ± 1 dB MIC : 30 Hz to 20 kHz, + 0 -3dB Tuner, AUX, Tape1, 2, Rec/PB (Input) : 20 Hz to 60 kHz, ± 3 dB
Tone control	Bass : 100 Hz ± 10 dB Treble : 10 kHz ± 10 dB
Loudness control	50 hz + 10 dB, 10 khz + 3.0 dB
Filter	High Filter : 5 kHz or higher, 6dB/oct. (Volume-30dB)
<General>
Semiconductor used	Transistor : 24 Diode : 9 IC:1
Pwer	100 VAC, 50Hz/60Hz
Power consumption	65W
External dimensions	Width 416x Height 119x Depth 285 mm
Weight	6.1kg