Audio Database


Accuphase P-650
680,000 yen(June, 2000 release)


Stereo power amplifier thrown in and developed in the element of the highest grade while investigating the reduction in the impedance of an amplifier output, and the constant-voltage drive of the speaker and inheriting old design technique.

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 130W and collector current 15A is adopted as an output element.
This element is constituted from a 6-parallel push pull, and efficient heat dissipation processing is performed by fixing on the heat sink by aluminum die-casting.

The current feedback type magnification circuit which returns an output signal in the form of current is adopted as a magnification circuit.
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. In this circuit, since the impedance of a return input portion is very low, it is hard to generate phase rotation and there is almost no necessity for phase compensation.
Many characteristics have improved sharply by a little NFB by this, it excelled in dynamic characteristics, such as a standup, and the natural energy response has been obtained.

The change of mono-/ stereo / bridge connection is possible at the mode changeover switch by the side of a rear panel.
By a dual mono-position, it is possible to use the output for center Woofers or to use it as an object for the by amplifier drive only for low-pass / high region.
Moreover, by a bridge position, it can be used as Oide power monophonic power amplifier by bridge connection. Bridge connection inputs a negative phase signal into two amplifier with which polarity differs, is connecting a speaker to the output end of both amplifier, and can supply the Oide power.

The printed circuit board by a Teflon (woven glass fabric fluoro-resin) board is adopted as an electric power magnification circuit.
Teflon has the features, like the heat resistance and the high frequency characteristic which have a low dielectric constant, and very little leak current between the patterns formed on the printed circuit board are excellent.
By use of the Teflon base, since the dielectric constant is low, the propagation velocity of a signal becomes quick and makes purer signal transmission possible from there being little path loss.

The balance input which cannot receive visitor guidance noise other than the usual imbalanced input easily is carried in the input terminal.

The plate with gold is given to the parts which a signal passes.
To P-650, a grounded plate, a capacitor terminal, an input terminal, a speaker terminal, etc. in which a printed board Copper-foil side and big ripple current flow are aiming at improvement in the thorough sound quality.

The large power-capacity Troy Dahl type of 1000VA which took the newly developed measures against a higher harmonic wave is adopted as a power transformer, and also it excels in heat conduction, and using the high load material of the vibrationproofing effect, it adheres to the unresonated aluminum case of efficient heat dissipation structure, and the influence on the exterior is intercepted.
The toroidal 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. Especially in P-650, 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 realized.
Moreover, two large scale types of 47,000 micro F are carried in the electrolytic condenser.

The large-sized speaker terminal also corresponding to a very-thick speaker cable is adopted.
Brass Naked material is used for the material of a terminal, it begins to delete, a golden plate is formed, and the mould cap of the insulated purpose is put from on the.

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

Rear Protection
Power Block Power Speaker

Rating of a mode
Form Stereo power amplifier
Continuation average output
(20Hz - 20kHz)
At the time of stereo specification : 650 W/ch (it restricts to 1 ohm and a music signal)
400 W/ch (2ohms)
200 W/ch (4ohms)
100 W/ch (8ohms)
At the time of monophonic specification :
(Bridge connection)
1300W (it restricts to 2 ohms and a music signal)
800W (4ohms)
400W (8ohms)
At the time of stereo specification : 0.05% (2ohms)
0.02% (4ohm-16ohm)
At the time of monophonic specification : 0.02% (4ohm-16ohm)
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: 4ohms - 16ohms
* Restrict to a music signal and Stereo 1 ohm and monophonic 2ohm load are possible.
Dumping factor 270 (at the time of a stereo / monophonic specification)
Input sensitivity (8-ohm load)
At the time of stereo specification : 1.12V (at the time of a rated continuation average output)
0.11V (at the time of 1W output)
At the time of monophonic specification : 2.25V (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) 120dB (at the time of input short-circuit and 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 80W (at the time of no inputting)
625W (Electrical Appliance and Material Control Law)
390W (at the time of an 8-ohm load Output power)
The maximum Dimensions Width 475x height 223x depth of 491mm
Weight 38kg