Audio Database


Accuphase P-300V
350,000 yen(July, 1987 release)


The Integrated Amplifier which constituted all to a drive stage from cascode connection excellent in the high frequency characteristic on the basis of all the magnification stage push pull drives.
It continues from the founder P-300, the model change is undergone with P-300S, P-300X, P-300L, and P-300V, and it hits the 5th generation, and also super-low impedance drive which also bears 1-ohm load, and realization of the more perfect balance input circuit are aimed at.

the broadband transistor whose collector loss Pc of an output stage is 130W -- 10 -- it is parallel and constitutes from a total of 20 pieces.
Thereby, if total Pc makes 70% power efficiency of per [ 2600W ] channel and an output stage, the theoretical marginal output amounts to 3700W, and has the structure where linear and good electric power is sendable also into a low load impedance by this.
20 transistors -- 10 -- it can be parallel, since it constituted, the large current at the time of low impedance load can also be coped with, and the low impedance of 1 ohm can also be driven.

Bridge connection is possible.
the same magnitude as amplifier with the same bridge connection -- a phase -- reverse (negative phase) -- it is the method of obtaining the double output in the 4-ohm load at the time of a stereo drive, by putting in a signal and connecting a speaker to the output end of both amplifier.
Usually, although a phase inversion circuit is inserted in one amplifier, the polarity of the difference input circuit of two amplifier is used, at the time of bridge connection, it is the method of making a connection change so that a negative phase signal may be inputted mutually, and it constitutes the pure change circuit from P-300V.

The full-scale 40kohm balance input is carried. It is possible to connect the balance output of all impedance with 3 P-XLR type connector of an international standard.
The balance input circuit of P-300V has the composition of pouring in a signal as it is, to plus of a difference input circuit, and a minus input, and has ideal composition.
Moreover, in the case of this system, a level control must be inserted in plus and each minus input, but the 1dB step Attenuator with few interlocking errors is adopted.

In order to suppress the switching distortion at the time of the Koide power produced in an output stage, the operating point is strictly set up so that the element of each PNP/NPN may not be cut off with an incoming signal. Moreover, the preceding paragraph which drives a final stage consists of cascode push pulls equivalent to a non switching Class-A drive by MOS FET. And the preceding paragraph is also considered as Class-A cascode push pull composition.
This has realized few stable output stages distorted from the Koide power of a noise domain to the Oide power of an Output power.

The input circuit constitutes the cascode bootstrap push pull circuit.
A cascode bootstrap circuit is further excellent in the frequency response and the phase characteristic of a super-high region with high gain, and is the circuit with which it was satisfied of the conditions with which the input stage that there is no aggravation of a distortion also to change of input impedance should be equipped.
constituting this circuit from a push pull -- a broadband drive stage -- conjointly -- the base in NF loop -- the characteristic is improved.

A power-source part prepares the winding only for a preceding paragraph magnification circuit in a transformer, rectifies right-and-left independence, and supplies it through a filter circuit.

The incoming signal has adopted the direct connection system direct inputted into Input.
For this reason, it is while omitting a direct current with direct-current servo system used as Accuphase original since there is a possibility of it being amplified, appearing in an output and damaging a speaker when the large preamplifier of direct-current drift etc. is connected,direct-current drift of the amplifier by a temperature change itself is also stabilized.

The output meter convenient to monitor is carried.
The Direct reading of the output electric power at the time of 8-ohm load can be carried out with dB in logarithm compression type peak power meter.

Three inputs of one balance and two unbalance are carried, and it can change with the switch of the front panel.
One line in an imbalanced input is prepared in the sub panel of the entire front panel.

Connection of A and B-2 system is possible for a speaker.
Since the speaker of those who are not using it may resonate in response to vibration and may spoil sound quality, it considers so that the speaker which is not operating may be short-circuited automatically and resonance may be prevented.

The surface panel upper part serves as gold tone scratch hair line finishing, and the lower sub panel serves as black hair line finishing.
Moreover, the sideboard of the natural persimmon is attached to both sides.


Rating of a mode
Form Stereo power amplifier
Output power
(20Hz - 20kHz, 0.01% of distortion)
At the time of stereo specification (both channel simultaneous operation)
2ohm load: 350 W/ch
4ohm load: 280 W/ch
8ohm load: 180 W/ch
16ohm load: 90 W/ch
At the time of monophonic specification (bridge connection)
4ohm load: 700W
8ohm load: 560W
16ohm load: 360W
THD At the time of stereo specification: 0.01%
(both channel simultaneous operation, 2ohms - 16-ohm load)
At the time of monophonic specification: 0.01%
(bridge connection, 4ohms - 16-ohm load)
IM distortion 0.003%
Frequency response 20Hz-20kHz+0 -0.2 dB
(at the time of a continuation average output level control MAX)
Gain 28.0dB (at the time of stereo monophonic specification)
Load impedance At the time of stereo specification: 2ohms - 16ohms
At the time of monophonic specification (bridge connection): 4ohms - 16ohms
Dumping factor At the time of stereo specification: 300
At the time of monophonic specification (bridge connection): 150
Input sensitivity (8-ohm load) At the time of stereo specification
At the time of a continuation average output: 1.5V
At the time of 1W output: 0.12V
At the time of monophonic specification (bridge connection)
At the time of a continuation average output: 2.7V
At the time of 1W output: 0.12V
Input impedance Unbalance: 20kohm
Balance: 40kohm
(the time of A compensation and stereo mono-specification)
120dB (at the time of input short-circuit and a continuation average output)
100dB (at the time of input 1kohm and 1W output)
Stereo headphone Conformity impedance: 4ohms - 100ohms
Power output meter Logarithm compression type
- 40dB - +3dB, and an output Direct-reading scale
A use transistor, a diode Transistor: 90 pieces
FEt: 16 pieces
IC: Eight pieces
Diode: 73 pieces
Power source AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption At the time of no inputting: 130W
Electrical Appliance and Material Control Law: 630W
At the time of an 8ohm load Output power: 600W
Dimensions the width 475x height 170(piece -- it includeds) x depth of 408mm
Weight 24.8kg