SONY/ESPRIT TA-N902
¥ 280,000 (around 1983)
Commentary
This is a stereo power amplifier that has been developed by carefully tuning the three elements of circuit, device and mechanism using ears and sensitivity for three and a half years.
The TA-N902 can be used in two ways : a stereo power amplifier and a monaural power amplifier. You can switch between them using the switch on the rear panel.
The power stage consists of a distortion reduction circuit and a Hi-fTIt consists of the SEPP output of an emitter follower with five transistors connected in parallel.
The Sony original distortion reduction circuit incorporated in this device controls the drive voltage so as to correct the linearity of the power stage, and operates the power element in A-class operation in most regions. This eliminates the NFB circuit to the pre-stage, greatly reduces the influence of the reaction of the TIM and the speaker load, and achieves higher sound quality.
The power supply section is equipped with two large power transformers for each channel on the left and right sides. This transformer is used as the core of the power supply section, combined with an electrolytic capacitor that reduces high-frequency impedance by examining sound quality.
We also pay attention to the power cord and use star quad structural wires with good transmission characteristics.
A symmetrical twin monaural configuration has been adopted for all stages. The ground line is a concentrated ground to eliminate harmful components generated the difference in ground potential between stages.
By adopting a layout in which the heat sink is exposed to the outside, it is possible to design a power supply circuit with sufficient space.
In addition, the heat sink itself is made of large, highly rigid aluminum die-cast to provide a strong structural base for the entire cabinet.
In addition, with attention paid to the effect of fin squeal on sound quality, we have made a special rubber vibration isolator with carefully examined shape and material and installed it in the most ideal position for audibility.
In consideration of the effect of the vibration of the transformer and condenser on sound quality, the transformer is filled with a material with excellent vibration resistance, and a rubber damper is interposed between the transformer and chassis to prevent vibration transmission between the transformer and chassis.
The condenser is also made of special damping material from the outside to suppress vibration.
In addition to the adoption of damping material to suppress the vibration of the top plate, the mounting leg of special material to remove unnecessary vibration component from the outside is adopted, and thorough vibration isolation design is applied.
Equipped with Route 3 input terminals.
The level and balance of the Variable connector can be adjusted with the attenuator on the front panel. A program source such as a CD player can be directly connected to the Variable connector to play in a purer state.
The two fixed jacks have fixed output levels and are designed to connect the preamplifier output to the Direct and Coupled jacks.
In order to solve the conventional problem of mechanical resonance and loss due to applied voltage, film capacitor is used. Film is tightly wound and fixed around it. In addition, the electrode and film itself are selected to have excellent mechanical strength and electrical characteristics, and the materials and bonding state of the lead wire, electrode junction, and electrode are also taken into consideration.
High-purity aluminum foil is used for both the anode and cathode of the large-capacity capacitor in the power supply section, and a chemical conversion method is adopted for the oxide film, which is a derivative of the capacitor, to optimize sound quality. In addition, a high-speed, low-distortion type electrolytic solution with excellent temperature stability is used, magnetic materials are eliminated from the terminal material to the plating, and high-frequency impedance is reduced to less than 1/2 of the conventional one.
We are the first in the world to use linear crystal (LC) -OFC for power supply and signal wires.
In LC-OFC, the size of the first class oxygen-free copper (purity of 99.995% or more) is enlarged and the number of crystal boundaries is reduced to reduce the degradation of music signals due to capacitive reactances. In LC-OFC, the number of crystals per 1 meter of normal OFC is more than 50,000, but in LC-OFC, the number of crystals is reduced to more than 20, so the apparent signal path is expanded by 2,500 times.
The front panel of the amplifier is equipped with a temperature monitor. After the power is turned on, it gradually changes to blue until the temperature reaches approximately 40 ℃, green under the best condition (40 ℃ to 90 ℃), and red when the temperature rises too much. If the overheat condition continues for a long time, the protection functions and the signal is cut off.
It is equipped with a peak power indicator that lights up the speaker output of the L or R channel, whichever is higher, in six levels depending on the level.
This indicator lights up fully and the protection is activated in case of overload.
Comes with removable JIS/EIA eia rack-mount mounting bracket for free setting.
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Model Rating
| Type | Stereo power amplifier | ||||||
| Circuit system |
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| Effective output (20 Hz to 20 kHz) |
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| Output bandwidth | 5 Hz ~ 80 kHz (at 65W output, 8 Ω load, rated harmonic distortion rate) | ||||||
| Slew rate | 120 v / μ sec (8 Ω) | ||||||
| Damping factor | 50 (1 kHz, 8 Ω) | ||||||
| Harmonic distortion factor (at effective output) |
0.1% or Less (8 Ω) 0.2% or Less (4 Ω, Monaural 8 Ω) |
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| Cross modulation distortion factor (at effective output) |
0.1% or Less (8 Ω) 0.2% or Less (4 Ω, Monaural 8 Ω) |
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| Residual noise | 30 μ V or Less (8 Ω, A Network) | ||||||
| Signal-to-noise ratio | 120 dB or more (closed circuit, A-network) | ||||||
| Frequency characteristic | DC ~ 100 kHz + 0 -3dB (Direct) 5 Hz to 100 kHz + 0 -3db (Coupled) |
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| Input Sensitivity / Impedance | 1.3V/50k Ω (Effective Output) | ||||||
| Speaker output | Stereo : Compatible with 4 Ω ~ 16 Ω Mono : 8 Ω ~ 16 Ω compatible |
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| Pwer | 100 VAC, 50Hz/60Hz | ||||||
| Power consumption | 330W | ||||||
| External dimensions | Width 480x Height 155x Depth 485 mm | ||||||
| Weight | 28kg | ||||||
| Rack mount | Possible with JIS standard rack (mounting pitch 100 mm) |