Accuphase P-300X
¥ 300,000 (released in June 1980)
Commentary
Based on the P-300 and P-300S, this is a stereo power amplifier that has been greatly improved by introducing the latest technology.
A MOS FET is used for the drive stage and a wide-band transistor is used for the output.
By using a MOS FET in the preceding stage, the bias voltage of the output stage is stabilized, and the emitter resistance of the output stage can be removed, so that the bias of the output transistor at the time of large output is not cut off and the generation of switching distortion is almost eliminated.
The MOS FET drive has a high input impedance, which makes it easier to operate in the previous stage, thus enabling higher performance.
The pre-drive stage employs a cascode connection of transistors for stable wide-band amplification.
The input circuit uses a cascode bootstrap differential push-pull input to obtain a large gain, improve the high-frequency characteristics, and prevent the deterioration of the distortion factor due to the increase of the input impedance.
By configuring the FET input, the input coupling capacitor is removed and connected directly.
In addition, DC feedback is applied by a DC servo amplifier to shut off DC, and DC drift generated in the circuit is suppressed.
In the power supply section, the power transformer is wound only on the right and left sides, and interference between the left and right sides caused by the exclusive rectifier and filter circuit is suppressed.
It has a built-in bridge circuit that enables you to use a stereo power amplifier as a monaural power amplifier. You can change it to a high-power monaural power amplifier by switching the switch.
In the bridge connection, the amplifier works in the + direction and the - direction respectively, and the voltage applied to the speaker is doubled, so the power is increased and the distortion is also canceled out, so the characteristics are also improved.
Equipped with a step-type attenuator that changes in 1 dB steps up to -20dB.
Equipped with a logarithmic compression type peak level meter, the output power of 8 Ω load can be read directly with the dB scale.
In addition, peak holding is possible by the meter function changeover switch, and the peak value during that period can be held and displayed every 3 seconds.
Input / output terminals are mounted on the front panel.
We have a wood cabinet sold separately.
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Model Rating
| Type | Stereo power amplifier | ||||
| Continuous average power (20 Hz to 20 kHz, Distortion Rate 0.01% or Less) |
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| Total harmonic distortion factor (0.25W ~ Rated Output, 20 Hz ~ 20 kHz) |
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| IM distortion factor (new IHF) | 0.003% | ||||
| Frequency characteristic | 20 Hz ~ 20 kHz + 0 -0.2 dB (Rated Output, Level Control Maximum) 0.4 Hz ~ 500 kHz + 0 -3.0 dB (output 1W, level control maximum) 0.4 Hz ~ 150 kHz + 0 -3.0 dB (output 1W, level control -6dB) |
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| Gain | Stereo : 27.8 dB Bridge connection : 33.8 dB |
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| Load impedance | Stereo : 4 Ω ~ 16 Ω Bridge connection : 8 Ω ~ 16 Ω |
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| Damping factor (new IHF, 50 Hz) | Stereo : 150 Bridge connected : 75 |
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| Input Sensitivity / Impedance |
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| S/N (A correction) |
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| Stereo headphone | Low output impedance type | ||||
| Subsonic filter | 17 Hz, -12dB/oct. | ||||
| Output meter | Logarithmic Compression Type, With Peak Hold Switching -40dB to + 3 dB and output direct reading scale |
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| Semiconductor used | Transistor : 42 FET : 12 IC : 7 Diode : 61 Units |
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| Power supply voltage | AC100V/117V/220V/240V, 50Hz/60Hz | ||||
| Power consumption | No input : 80W 8 Ω load rated output : 550W |
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| External dimensions | Normal : 445 mm width x 160 mm height (including legs) x 373 mm depth With Wood Case : Width 466x Height 190 (Including Legs) x Depth 385 mm |
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| Weight | 22.5kg | ||||
| Sold Separately | Wood Case A-8 (¥ 16,000) |