Audio Database

The

Accuphase P-370
360,000 yen(March, 2001 release)

Description

Stereo power amplifier which inherited the design technology cultivated so far and applied the polish to sound quality further by maturing of technology and sensitivity.

It excelled in many characteristics, such as a frequency response, a current gain linearity, and switching, and the high power transistor of the collector loss 150W and collector current 15A is adopted as an output element. This transistor was constituted from a 3 parallel push pull, and effective heat dissipation processing is realized by attaching on a large-sized heat sink.
This has realized Oide power even with linear super-low impedance load.

The current feedback (current feedback type) magnification circuit which returns an output signal in the form of current is adopted.
The principle of this circuit lowers the impedance of the input terminal by the side of a return first, detects current, carries out I-V (current-voltage) conversion of that current with a transformer impedance amplifier, and makes an output signal.
Since the impedance of the return input portion is very low, it was hard to generate phase rotation and, as a result, the necessity for a phase guarantee of it has almost been lost. For this reason, since the characteristic is sharply improvable by a little NFB(s), the natural energy response excellent in dynamic characteristics, such as a standup, has been realized.

In the power-source part, the large power-capacity Troy Dahl type of about 700 VA is adopted as a power transformer. Furthermore, the high load material of the A vibrationproofing effect was used for heat conduction, it adhered to the case, and the influence on the exterior is prevented.
The Troy Dahl type transformer has the features, like impedance is very low, it is small, and conversion efficiency is high in order to coil thick copper wire around a doughnut-like core. In P-370, the super ring type was adopted, the section of the iron core was close to the circle, the coil could also be rolled closely circularly, and since adhesion nature is good, the outstanding characteristic has been acquired.
Moreover, two 47,000-micro F mass capacitors are carried in the aluminum electrolytic capacitor.

The input terminal strong against external guidance noise for balance connection is carried.

It can be used also as monophonic power amplifier by bridge connection.
Bridge connection inputs a negative phase signal into two amplifier with which polarity differs, is the method of connecting a speaker to the output end of both amplifier, and can supply richer power.
The mode changeover switch by the side of a rear panel performs a change. By a dual mono-position, it is possible to use the output for center Woofers, or to output channel signal of one of the two from both the speaker terminal, and to use it for a by amplifier drive.

The analog type large-sized power meter is carried.
The switch which turns on and off operation and lighting of meter is also carried.

Two speaker terminals which can respond also to a thick speaker cable are carried.
Usually, although it is used changing, it is also possible to operate A/B both systems and to make bi-wiring connection.

Rear Power
Use
Ass(ies), Power Filter Large-sized
A

Rating of a mode
Form Stereo power amplifier
Rated continuation average output
(20Hz - 20kHz)
At the time of stereo specification : 400 W/ch (it restricts to 1 ohm and a music signal)
300 W/ch (2ohms)
150 W/ch (4ohms)
75 W/ch (8ohms)
At the time of monophonic specification :
(Bridge connection)
800W (it restricts to 2 ohms and a music signal)
600W (4ohms)
300W (8ohms)
THD
At the time of stereo specification : 0.05% (2-ohm load)
0.02% (4ohms - 16-ohm load)
At the time of monophonic specification : 0.02% (4ohms - 16-ohm load)
IM distortion 0.003%
Frequency response 20Hz-20kHz+0 -0.2 dB (at the time of a rated continuation average output)
0.5Hz-160kHz+0 -3.0dB (at the time of 1W output)
Gain 28.0dB (at the time of a stereo / monophonic specification)
Load impedance At the time of stereo specification: 2ohms - 16ohms
At the time of monophonic specification (bridge connection): 4ohms - 16ohms
* Restrict to a music signal and Stereo 1 ohm and monophonic 2ohm load are possible.
Dumping factor 200 (at the time of a stereo / monophonic specification)
Input sensitivity (at the time of 8-ohm load)
At the time of stereo specification : 0.98V (at the time of a rated continuation average output)
0.11V (at the time of 1W output)
At the time of monophonic specification :
(Bridge connection)
1.95V (at the time of a rated continuation average output)
0.11V (at the time of 1W output)
Input impedance Imbalanced Input: 20kohm
Balance input: 40kohm
S/N
(A compensation, input short-circuit)
120dB (at the time of a rated continuation average output)
Power output meter A logarithm compression type, with a display putting-out-lights function
- 50dB - +3dB
Power source AC100V, 50Hz/60Hz
Power consumption 44W (at the time of no inputting)
475W (Electrical Appliance and Material Control Law)
335W (at the time of an 8-ohm load Output power)
The maximum Dimensions Width 475x height 180x depth of 417mm
Weight 24.4kg
Attachment AC power cord