Audio Database

The

Accuphase P-300S
\260,000 yen(September, 1977 release)

Description

Stereo power amplifier which constituted all the magnification stages from a symmetrical type push pull, and also realized the physical characteristic of the measurement limit by the formation of direct-current unit amplifier, adoption of a careful selection part, and an audition test.

Based on the active device which was excellent in the high frequency characteristic, all the magnification stages consist of symmetrical type push pulls.
The standup characteristic, linearity, and stability excellent in a little NFB could be realized by this, and while preventing generating of TIM, low distorted-ization is realized.

In order to realize sound quality with few colorations, the condenser in a NFB loop is removed and it has direct-current amplifier composition.
Moreover, long-term operational stability is realized by stabilizing a power source much more, in order to suppress direct-current drift, adopting a dual transistor as an input, and stabilizing center voltage, and also attaining equalization of the temperature change of an active device.

The heavy weight class large-sized power transformer and the mass filter capacitor of 40,000 micro Fx2 are carried in the power-source part.
Moreover, the parts currently used for the circuit have adopted what was selected carefully based on the examination about sound quality change, a durability test, etc.

When the speaker protection circuit is carried and abnormalities occur to the short circuit, and amplifier/speaker of a speaker cord, a speaker protection circuit catches abnormalities and intercepts between P-300S and a speaker by relay.
Moreover, measures are taken so that the shock noise generated when the power source of amplifier is turned on and off using this circuit may not be generated, either.

In order to cut the low-pass noise by the curvature and eccentricity of a record, the Subsonic Filter which cuts 17Hz or less by 18 dB/oct is carried.

- Carry the right-and-left independent type Attenuator which can be adjusted at a 1dB step to 20dB.

The output Direct-reading type large-sized power meter is carried, and the number of watt at the time of 0dB and 8-ohm load can be read for an output.
Moreover, a range changeover switch of -10dB-20dB is prepared so that it can use also in the time of small volume.

For a reason when you would like to restrict the power more than needed, the power limiter switch is carried. Full power, 1/2, and 1/4 can be chosen.

There was a wood case of natural tree walnut finishing as an option.


At Rear
A
Internal

Rating of a mode
Form Stereo power amplifier
Output power
(Bothchannel drive, 20Hz - 20kHz, 0.03% or less of distortion)
200 W/ch (4ohms)
150 W/ch (8ohms)
75 W/ch (16ohms)
THD (20Hz - 20kHz) 0.03% or less (at the time of an Output power)
0.01% or less (at the time of a -3dB output)
0.05% or less (at the time of a 50mW output)
IM distortion 0.01% or less (at the time of an Output power)
Frequency response 20Hz-20kHz+0 -0.2dB (at the time of an Output power)
1Hz-250kHz+0 -3dB (at the time of 1W output)
Dumping factor (8-ohm load, 40Hz) 60
A rated input / input impedance 1.4V/50kohm
S/N ratio (input short-circuit, IHF-A curve) 115dB or more (at the time of an Output power)
Stereo headphone Low Output-load-impedance type
Subsonic Filter 17Hz, 18 dB/oct
Power limiter Full power, 1/2, 1/4, a switch change
The semiconductor used Transistor: 97 pieces
FET: Two pieces
IC: One piece
Diode: 92 pieces
Power supply voltage AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption At the time of no inputting: 100W
At the time of an 8ohm load Output power: 510W
Dimensions the width 445x height 160(piece -- it includeds) x depth of 355mm
Weight 25kg
Option Wood case A-2 (15,000yen)