Accuphase P-370
¥ 360,000 (released in March 2001)
Commentary
This is a stereo power amplifier that has inherited the design technology that has been cultivated over the years and has polished the sound quality by maturing the technology and sensitivity.
The output device uses a high-power transistor with a collector loss of 150W and a collector current of 15A that has excellent characteristics such as frequency characteristics, linearity of current amplification factor and switching. This transistor is composed of 3 parallel push-pull and is mounted on a large heat sink to realize effective heat radiation processing.
This realizes linear high output power up to ultra-low impedance loads.
It uses a current feedback amplifier circuit that feeds back the output signal in the form of current.
The principle of this circuit is that a current is detected by reducing the impedance of the input terminal on the feedback side, and the current is converted to I-V (current-voltage) by a transimpedance amplifier to produce an output signal.
Since the impedance of the feedback input part is extremely low, phase rotation hardly occurs, and as a result, there is almost no need for phase guarantee. Therefore, the characteristics can be greatly improved with a small amount of NFB, and a natural energy response with excellent dynamic characteristics such as rising is realized.
The power supply section uses a toroidal power transformer with a large power capacity of approximately 700 VA. In addition, it is fixed to the case using a filler with excellent heat conduction and anti-vibration effect to prevent external influence.
Toroidal transformers have features such as extremely low impedance, small size and high conversion efficiency because thick copper wire is wound around a doughnut-shaped core. The P-370 uses a super-ring type, and has excellent characteristics because the cross-section of the iron core is close to a circle and the coil is close to a circle and adhesion is good.
The aluminum electrolytic capacitor is equipped with two 47,000 μ F large-capacity capacitors.
It has an input terminal for balanced connection that is resistant to external induction noise.
It can also be used as a monaural power amplifier by bridge connection.
In the bridge connection method, two amplifiers with different polarities are fed with opposite phase signals, and a speaker is connected to the output terminals of both amplifiers. This way, more power can be supplied.
Use the mode selector switch on the rear panel. In the dual mono position, it can be used as an output for the center woofer or as a single channel signal output from both speakers for bi-amplifier drive.
Equipped with an analog type large power meter.
It also has a switch to turn on/off the meter operation and lighting.
Equipped with two speaker terminals that can be used with thick speaker cables.
Although it is normally used by switching, it is also possible to operate both A and B systems for bi-wiring connection.
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Model Rating
| Type | Stereo power amplifier | ||||
| Rated continuous average output (20 Hz to 20 kHz) |
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| Total harmonic distortion factor |
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| IM distortion factor | 0.003% | ||||
| Frequency characteristic | 20 Hz ~ 20 kHz + 0 -0.2 dB (at rated continuous average output) 0.5 Hz ~ 160 kHz + 0 -3.0 dB (at 1W Output) |
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| Gain | 28.0 dB (both stereo and monaural specifications) | ||||
| Load impedance | Stereo specification : 2 Ω ~ 16 Ω Monaural specification (bridge connection) : 4 Ω ~ 16 Ω * Only for music signals, stereo 1 Ω and monaural 2 Ω loads are possible. |
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| Damping factor | 200 (both for stereo / monaural specifications) | ||||
| Input sensitivity (at 8 Ω load) |
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| Input impedance | Unbalanced input : 20k Ω Balance Input : 40k Ω |
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| S/N (A correction, input short) | 120 dB (at rated continuous average output) | ||||
| Output meter | Logarithmic Compression Type with Display / Off Function -50dB to + 3 dB |
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| Pwer | 100 VAC, 50Hz/60Hz | ||||
| Power consumption | 44W (non-input) 475W (Electrical Appliance and Material Control Law) 335W (at 8 Ω load rated output) |
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| Maximum external dimensions | Width 475x Height 180x Depth 417 mm | ||||
| Weight | 24.4kg | ||||
| Attachment | AC power cord |