Audio Database


Accuphase P-11
230,000 yen(July, 1989 release)


Stereo power amplifier which aimed at improvement in low impedance drive capability which sends in sufficient energy for a speaker not only with basic engine performance, such as a frequency response, a distortion, and S/N, but complex nature.

The output stage constitutes the large-sized output transistor of Pc(collector loss)130W from a 3 parallel push pull, and has gained the output stabilized by this also at the time of low impedance.
Moreover, the original power MOS FET of only an Accuphase is adopted as a drive stage as an electric power element which was excellent in the characteristic of bearing the high voltage.

The buffer stage is prepared in order to prevent interference with the preamplifier which is making the differential amplification stage take charge of voltage magnification of the preceding paragraph, and is connected in front of this stage, and an input level control.
The cascode system by FET is adopted as this buffer stage, it excels in the high frequency characteristic, and operation stabilized also in a large change of input impedance is carried out.

The large-sized toroidal transformer which was excellent in rate of change is adopted as a power-source part, and margin sufficient also at the time of the maximum except take-off is given to it.
Moreover, in order to prevent the mutual intervention in each stage, it has supplied and separated into an output stage and each preceding paragraph from the winding wire with which the transformer became independent. Furthermore, the preceding paragraph carries out right and left to independent composition with an exclusive commutator and a filter, and is suppressing interference of the order stage and the right-and-left channel to the minimum.

The incoming signal has adopted the direct connection system inputted direct.
When the large preamplifier of direct-current drift etc. is connected, it is amplified and it appears in an output, and in order to prevent damaging a speaker, while having adopted direct-current servo system and omitting a direct current, direct-current drift of the amplifier by a temperature change itself is stabilized.

Use is possible with bridge connection also as monophonic power amplifier in which a more powerful output is possible.
Bridge connection is inputting the signal of 180 degrees (negative phase) of phase difference in the same magnitude as the same amplifier, and taking out sy copy power from the output end of both amplifier,It is equivalent to carrying out the push pull drive of two sets of the amplifier with the system that the twice as many output in the 4-ohm load at the time of a stereo drive as this will be obtained at the time of 8-ohm load.
Usually, although a phase inversion circuit is inserted in one amplifier at the time of bridge connection, the polarity of the difference input circuit of two amplifier is used, and the ideal change circuit which inserts no amplifier consists of P-11.

The balance input full-scale besides the usual phono jack input is carried.
The balance input circuit of P-11 is considered as the ideal composition which inputs a signal into plus of a difference input circuit, and a minus input as it is.
Moreover, the 1dB step twin Attenuator with few interlocking errors is adopted as the level control which must be inserted in each of plus and minus in this case.

Two output terminals are carried so that 2 sets of speakers can be driven.
It is controlled by the large current relay which became independent, respectively, and in A+B, two lines become parallel connection and a bi-wiring speaker can be connected.

The overload indicator which tells a maximum-except-take-off level is carried.

Based on the panel of champagne gold scratch hair line finishing which is the keynote of an Accuphase, a display with thick glass is prepared in the center, and it has become the design which processed both sides by the thick metal end block.

Internal Power

Rating of a mode
Form Stereo power amplifier
Continuation average output (20Hz - 20kHz)
At the time of stereo specification (both ch(es) operation) : 170 W/ch (4ohms)
120 W/ch (8ohms)
60 W/ch (16ohms)
At the time of monophonic specification (bridge connection) : 340W (8ohms)
240W (16ohms)
At the time of stereo specification (both ch(es) operation) : 0.02% (4ohms)
0.01% (8ohm-16ohm)
At the time of monophonic specification (bridge connection) : 0.02% (8ohm-16ohm)
IM distortion 0.003%
Frequency response 20Hz-20kHz+0 -0.2 dB (at the time of a continuation average output level-control maximum)
0.5Hz-160kHz+0 -3.0 dB (at the time of 1W output the level-control maximum --6dB)
Gain (profit) 28.0dB (at the time of a stereo / monophonic specification)
Load impedance At the time of stereo specification: 4ohms - 16ohms
At the time of monophonic specification (bridge connection): 8ohms - 16ohms
Dumping factor At the time of stereo specification: 200
At the time of monophonic specification (bridge connection): 100
Input sensitivity (8ohms)
At the time of stereo specification
(both chanenl operation) :
1.23V (at the time of a continuation average output)
0.12V (at the time of 1W output)
At the time of monophonic specification
(bridge connection) :
2.08V (at the time of a continuation average output)
0.12V (at the time of 1W output)
Input impedance Balance: 40kohm
Unbalance: 20kohm
S/N (A compensation) 115dB (at the time of input short-circuit and a continuation average output)
93dB (at the time of input 1kohm and 1W output)
Stereo head phone Conformity impedance: 4ohms - 100ohms
The semiconductor used Transistor: 41 pieces
FET: 14 pieces
IC: Four pieces
Diode: 60 pieces
Power supply voltage AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption At the time of no inputting: 45W
Electrical Appliance and Material Control Law: 300W
At the time of an 8ohm Output power: 480W
Dimensions the width 445x height 131(piece -- it includeds) x depth of 388mm
Weight 18.1kg