YAMAHA A-2000a
¥ 195,000 (around 1987)
Commentary
A pre-main amplifier equipped with a Dual Amp Class A with ZDR circuit by combining a pure class A amplifier and a high power class AB amplifier (bootstrap amplifier).
The ZDR circuit cancels output stage is also canceled by the ZDR circuit.
Equipped with Yamaha's original RICHNESS CIRCUIT.
The NS-1000x / NS-1000M -1000x / NS-1000M, and general-purpose reinforce the low-frequency f-special with the most natural one octave width. 2000
For the capacitor of the power supply section, an audio Chemicon with a hyperfractionation foil multi-terminal structure is adopted from the standpoint of emphasizing sound quality. The two channels of 55000 μ Fx2 in the current amplifier stage and 4700 μ Fx2 in the voltage amplifier stage provide a large capacitance of approximately 240000 μ F in total.
In addition, by adopting a transformer with independent pre-amplifier and power amplifier sections, stable power supply is possible even under dynamic load fluctuations.
In addition, by using a non-current ground and one point ground that does not supply power to the ground, modulation and wamble of the output signal are eliminated and amplification stability is maintained.
The volume employs a precision 4-series volume that is narrowed down at the front and back of the flat amplifier, and noise is suppressed even at low volume by improving the S/N ratio in actual use.
Quality parts such as copper-plated chassis, oxygen-free copper wires, and gold-plated pin jack terminals are used to improve sound quality.
Exterior features include solid aluminum machined volume knob, sealing panel internal knob, poly-coated real walnut side panel, etc.
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Model Rating
| Type | Pre-main amplifier |
| Rated Output (20 Hz ~ 20 kHz) | 150W + 150W (6 Ω, 0.003% strain) 130W + 130W (8 Ω, 0.003% strain) |
| Power bandwidth | 10 Hz ~ 100000 Hz (65W, 8 Ω, Distortion 0.02%) |
| Damping factor | 200 or More (1 kHz, 8 Ω) |
| Input Sensitivity / Impedance | Phono1 MC : 100 μ V/100 Ω, 1k Ω Phono1 MM : 2.5mV/47k Ω (220 pF, 330 pF) 100 Ω Phono2 mm : 2.5mV/47k Ω 220 pF AUX : 150mV/47k Ω Main In : 1V/100k Ω |
| Total harmonic distortion factor | MC:0.004% AUX:0.003% Main In:0.002% |
| RIAA deviation | MM, MC : 20 Hz to 20000 Hz, ± 0.2 dB |
| S/N ratio (IHF-A) | MC:83dB MM:88dB |
| Richness | 1 : + 7.5 dB, 30 Hz 2 : + 7.5 dB, 40 Hz 3 : + 7.5 dB, 50 Hz |
| Pwer | 100 VAC, 50/60Hz |
| Power consumption | 420W |
| External dimensions | Width 473x Height 169x Depth 464 mm |
| Weight | 26kg |