SONY TA-N86

Commentary

Pulse power supply or Hi-f_TA stereo power amplifier developed with the latest technologies such as transistors.

In order to improve the distortion of the original sound waveform due to phase rotation in the low frequency range and the deterioration of reproducibility of overtone components due to the deterioration of transient response characteristics in the high frequency range, the DC amplifier and Hi-f are improved._TWe aim to improve sound quality by two means of development of transistor.

The first stage uses a dual FET with very low temperature drift, which was developed by taking advantage of Sony's proprietary semiconductor technology, to stabilize the operating point that causes problems in DC amplifiers.

Hi-f for the power transistor_TTransistor is used.
Bipolar transistors tend to have poor response characteristics to high-frequency signals as power is increased. This causes switching distortion and reduces the quality of high-frequency signals. In order to improve this point, Hi-f with a fine line-like pattern is adopted._TA transistor has been developed to enable stable operation even at high power. this Hi-f_TThe transistor is like an integration of numerous low-power transistors with good high-frequency response characteristics. The cut-off frequency is extended from 4 MHz to 20 MHz to 60 MHz or more, and the high-frequency response speed is extremely fast, thus improving the reproducibility of the high-frequency range.

The voltage amplification stage is a 3-stage differential DC amplifier configuration.
In this circuit, we seek to improve the bare characteristics before applying NF, so that the distortion factor is extremely low. In addition, the distortion in the NF loop is also reduced because the gain is sufficient. In addition, a constant current circuit with large impedance is inserted in the first stage (source side) and the next stage (emitter side) to suppress fluctuations in the power supply current and improve the sound quality.

The power amplifier consists of 3-stage Darlington DC amplifier.
In general, it is necessary to increase the load resistance of the transistor in order to obtain a large gain in the voltage amplification stage and the middle stage. In this case, the input impedance of the power amplification stage must be high enough. The Darlington connection effectively doubles the internal resistance of the transistor, making the most of the capacity of the voltage amplification stage and the middle stage.

The power supply section uses a pulse power supply that was created after four years of development.
The pulse power source directly rectifies AC100V to convert it into a 20 kHz pulse, and then rerectifies it after reducing it with a high-frequency transformer. This method reduces voltage fluctuation, but the TA-N86 uses a pulse-width-controlled constant-voltage circuit in combination with the TA-N86. The pulse-width-controlled constant-voltage circuit converts the voltage fluctuation into a pulse width change. In the form opposite to the pulse waveform, the DC obtained by the primary rectifier circuit is turned ON / OFF to obtain a voltage with the fluctuation canceled. Thus, the voltage fluctuation rate is than 1%.
With pulse power supply, AC100V is turned DC as soon as it is in the amplifier, so there is basically no magnetic leakage caused by 50Hz/60Hz AC power supply. Therefore, there is no signal system interference due to hum. With pulse rectification method, DC state is almost achieved just by rectification, and the pulse current component is only equivalent to the switching time of the transistor that converts DC to pulse, and the pulse current component is almost 0.

It is possible to switch between class A operation, class B operation and monaural operation.
For switching between class A and class B, we have adopted a design in which the method of supplying bias current is changed by a relay circuit, making it possible to easily switch between class A and class B. In addition, a lead relay is provided at an appropriate position on the printed circuit board, and the switch on the rear panel is controlled remotely to minimize the signal path.

The internal construction is a twin mono configuration in which the left and right channel signal systems are separated, reducing sound quality degradation due to mutual interference.

Model Rating

Type	Power amplifier
Circuit system	All Stages Directly Connected Pure complimentary service SEPPOCL 3-stage differential voltage amplifier, 3-stage Darlington power amplifier
Effective power (20 Hz to 20 kHz, both channel operation)	Class A operation : 18W + 18W (8 Ω) Class B operation : 80W + 80W (8 Ω) Monaural amplifier operating : 200W (8 Ω)
Signal-to-noise ratio	120 dB or more (closed circuit, A-network)
Harmonic distortion factor	20 Hz to 20 kHz 5 Hz to 50 kHz Effective output time At 10W output At 1W output Class A : Class B : mono: Class A : Class B : mono: Class A : Class B : mono: 0.007% 0.007% 0.015% 0.0025% 0.0035% 0.008% 0.001% 0.003% 0.008% 0.02% 0.02% 0.07% 0.005% 0.007% 0.03% 0.006% 0.007% 0.025% * The distortion factor at the time of 1W output is measured with a spectrum analyzer after removing noise components.
Cross modulation distortion factor (60Hz:7kHz=4:1)	Effective output time At 10W output At 1W output Class A : Class B : mono: Class A : Class B : mono: Class A : Class B : mono: 0.004% 0.004% 0.005% 0.002% 0.003% 0.004% 0.002% 0.003% 0.004%
Output bandwidth characteristics	5 Hz to 45 kHz (Class B operation, IHF, 8 Ω) 5 Hz ~ 60 kHz (Class A operation, IHF, 8 Ω) 5 Hz ~ 30 kHz (Monaural Operation, IHF, 8 Ω)
Damping factor	70 (1 kHz, 8 Ω)
Residual noise	25 μ V (8 Ω, A Network)
Frequency characteristic	DC ~ 200 khz + 0 -1dB (Direct Terminal) 7 Hz ~ 200 kHz ± 1 dB (C-Coupled Terminal)
Gain	Class A : 27.4 dB Class B : 27.4 dB mono:33.4dB
Input sensitivity	1.1 V (at Class B effective output)
Impedance	50k Ω
Output terminal	Speaker Class B Operation : Compatible with 4 Ω ~ 16 Ω Class A, monaural operation : suitable for 8 Ω ~ 16 Ω speakers
Semiconductor used	Transistor : 63 Diode : 54 pcs FET : 4 pcs
Pwer	100 V, 50Hz/60Hz
Power consumption	180W
External dimensions	Width 480x Height 80x Depth 360 mm
Weight	8.0kg