SONY TA-NR10
¥ 800,000 (around 1992)
Commentary
This monaural power amplifier is based on TA-NR1 and enhanced with custom-made power MOS FET.
Custom-made power MOS FET is used for the output stage.
Power MOS FETs have excellent bubble characteristics. First of all, since they are voltage controlled devices, there is no current flow from the preceding stage, and mutual interference between stages can be eliminated. Also, there is no charge storage effect that causes switching distortion due to majority carrier control. In addition, the input and output show good enhancement characteristics. Especially when used as an complimentary service pair, they cancel each other's squared characteristics which are similar to each other, and high linearity can be obtained up to a minute level.
In the TA-NR10, we focused on this power MOS FET and newly developed and mounted a custom-made power MOS FET with a large capacity of 200 V withstand voltage and 12A maximum drain current. Moreover, non-magnetic gold plating is applied to the mounting base and lead. This element is a 10 parallel push-pull configuration with pure A-class operation, giving a wide current supply capability and enabling 1 Ω load continuous drive without load switching.
In addition, bare distortion is minimized by the amplifier operation unique to pure A-class, and NFB is limited to a low feedback amount of 6 dB.
A pure copper block is used for the heat sink to fix the output stage.
Pure copper has approximately 1.6 times the thermal conductivity of ordinary aluminum. The base thickness is 18 mm and each unit is 10 kg. This heat sink has high heat radiation characteristics that can be used with natural air cooling and vibration control that suppresses noise of output elements.
The power supply section uses a silent S. T. D. (スポンティニアス Twin Drive) power supply.
In the S. T. D. system, the supply to each stage is separated from the rectifier circuit to eliminate interference at high output.
The power transformer employs a 10 kg low-leakage flux toroidal transformer with an enlarged core size of φ 120 mm. The smoothing capacitor employs a multielement aluminum electrolytic capacitor with a stacking structure that improves sound quality by equalizing characteristic distribution by separating and laminating electrode foils. The voltage amplifier stage is equipped with 9,200 μ Fx2/330 μ Fx2, and the power amplifier stage is equipped with 22,000 μ Fx2.
A high-carbon steel chassis is used for the chassis.
The material is cast iron used as the base of machine tools and has high rigidity and excellent vibration damping characteristics. This material has a rigid structure with a maximum wall thickness of 21 mm and a weight of 10.5 kg, which firmly supports heavy parts.
In addition, the internal construction has a symmetrical configuration in which power blocks are arranged symmetrically with the power supply between them, giving a good balance in terms of electrical and weight.
In addition to the unbalanced input, the XLR terminal balanced input is also equipped. The balanced input is also equipped with positive / negative phase input of pin-jack specification. Power can be increased by connecting two TA-NR10 units by bridge connection.
The front and rear panels are made of extruded aluminum with a thickness of 7 mm. The top panel is made of extruded aluminum with a glass-fiber reinforced mold vent. The corner posts are also made of extruded aluminum. Wood is used for both side plates facing the circuit board of the power block. In addition, the bottom plate is made of a combination of iron and bakelite, making it an acoustic tune structure that matches the sense of hearing.
The parts used are mainly composed of sound quality parts, and reliable parts are used in consideration of listening characteristics that cannot be understood from specifications alone. Especially for the signal system, from one resistor to one capacitor are selected after trial listening.
For each circuit board of voltage amplification stage and power amplification stage, an OFC rolled copper foil 70-micron thick glass sandwich board with enhanced damping is adopted.
The balanced input transformer uses a large super-permalloy core that boasts high permeability due to its uniform material properties, and realizes low distortion over the entire signal band.
A specially designed vice type speaker terminal with a brass machined gold plated finish is used for the speaker terminal.
A banana jack is also provided separately to accommodate a banana plug.
The leg uses an insulator made of cast iron.
Non-resilient rubber is used for the contact surface between the insulator and the floor to suppress vibration.
Equipped with a protection circuit by overcurrent / DC detection method.
High-quality 12-contact 6-para relay is used.
The power cord uses Class 1 OFC and has a very thick 2-core structure with a soft sheath. This cable has a polarity indicator on the plug.
The power cord is pulled out from the bottom plate directly below the transformer.
Equipped with an analog type temperature meter with back light, the operating temperature of the amplifier can be monitored from the time of warm-up.
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Model Rating
| Type | Monaural power amplifier | ||
| Circuit system |
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| Effective power |
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| Total harmonic distortion factor | 0.005% (at 8 Ω load, 10W output) 0.05% (8 Ω Load, Effective Output) 0.08% (4 Ω Load, Effective Output) |
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| Cross modulation distortion factor | 0.05% (8 ohm load, effective output, 60 hz : 7 khz = 4 : 1) | ||
| Damping factor | 100 or More (1 kHz, 8 Ω) | ||
| Residual noise | 30 μ V or less (A Network) | ||
| Signal-to-noise ratio | 120 dB or more (A network) | ||
| Frequency characteristic | 5 Hz ~ 100 kHz + 0 -3dB | ||
| Input Sensitivity / Impedance | Unbalanced : 1.1V/47k Ω Balanced : 0.55V/600 ohm |
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| Adaptive load impedance | 1 Ω ~ 16 Ω | ||
| Pwer | 100 VAC, 50Hz/60Hz | ||
| Power consumption | 460W | ||
| External dimensions | Width 470x Height 220x Depth 455 mm | ||
| Weight | 62kg |