Accuphase P-600
¥ 650,000 (released in April 1983)
Commentary
A stereo power amplifier developed in pursuit of the ideal power amplifier for the new era.
To compensate for the large output with continuous operation, the output stage consists of 14 wide-band transistors with a Pc (collector loss) of 200W per channel, 7-parallel push-pull, providing a power capacity of 2.8 kW.
It is possible to drive a low load of up to 2 Ω even under normal operating conditions. However, a Low Load Impedance Operation switch is provided to drive with even lower impedance for commercial use.
This switch allows a large current to be supplied while maintaining the safety of the output transistor, so that an output of 450W/ch can be obtained for a 1 Ω load.
The drive stage that drives the output stage is composed of a MOS FET for power amplification. It performs low-impedance large-current drive and significantly improves high-frequency characteristics.
Since the thermal characteristics stabilize the bipolar transistor, the bias current of the output stage is stabilized. As a result, the emitter resistance of the output stage can be lowered. Moreover, the equivalent emitter resistance of 1/7 is lowered by 7-parallel, and the switching distortion caused by the cutoff of the bias of the output transistor is almost eliminated.
The pre-drive stage consists of a Darlington cascode push-pull, which drives a MOS FET with excellent high frequency characteristics without mirror effect and high amplitude operation with good linearity.
In addition, the Darlington connection composed of the pre-drive stage increases the input impedance of this stage so that it does not affect the operation of the differential input circuit, which becomes a load, enabling high-quality amplification.
The input amplifier circuit uses a cascode bootstrap push-pull circuit of the FET input.
The cascode bootstrap is high gain and improves the high-frequency characteristics to prevent the deterioration of the distortion caused by the increase of the input impedance (change of input level control).
It uses a push-pull input circuit with dual FET so that the input capacitor can be removed without generating DC at the input.
In addition, in order to prevent DC from appearing at the output and adversely affecting the speaker when used in combination with a DC leakage preamplifier, DC feedback is applied by a DC servo amplifier to cut off DC and to suppress the drift generated in the circuit.
It can also be used as a monaural amplifier by bridge connection.
The principle of bridge connection is that by inputting signals of the same waveform and opposite phase to each amplifier and connecting the speakers to the outputs of both amplifiers, the voltage applied to the speakers is doubled, and in principle four times the output can be taken out.
It also has the advantage that even harmonic distortion is canceled due to the reverse phase drive, and the characteristics are improved. In addition, since the energy flowing from the power supply flows alternately in positive and negative directions and the energy in only one direction does not flow to both amplifiers, the apparent power fluctuation factor is improved, and energy with good linearity can be sent to the speakers.
In addition to the normal 20k Ω unbalanced input (phono jack), a full-scale 600 Ω balanced input (3P cannon type) is equipped.
The phase inversion of the P-600 balance input is not a transformer, but a low-differential-band 歪広 amplifier circuit is adopted.
Equipped with a digital power meter that can directly read peak values.
Digital power meters consist of a 12-bit A/D converter and a 4-bit microprocessor. Analog signals are converted to digital signals by an A/D converter for accurate display.
Since the display is 3-digit, it is equipped with range switching so that you can directly read from 0.001W to 999W by range switching. You can also choose a hold time of 3 seconds or 30 minutes. If you use the 30 minute range, you can read the peak value of one side of the record and know the maximum cutting level.
The digital power meter of the P-600 converts the output voltage into electric power and displays it. However, even if the output voltage is the same, the output power varies greatly depending on the speaker impedance. In order to display the accurate output power, an impedance selector switch for the power meter is provided to adjust the operation of the display to the nominal impedance of the speaker.
Equipped with a 25-contact rotary switch for communication equipment and a full-scale attenuator with high precision resistance.
A 1-dB step can be selected between 0 dB and -20dB, followed by -23dB, -26dB, -30dB and - ∞ with a precision of ± 0.1 dB.
Equipped with a subsonic filter.
For switching the filter, a relay is installed in the circuit on the printed circuit board, and this relay is controlled by a switch on the front panel to prevent deterioration of characteristics.
We have a Persimmon panel with 24 mm thick wood finish sold separately.
There is a heat radiation fan sold separately, and the fan can be installed when it is set in a place where heat radiation effect is bad or when large output drive is carried out for a long period.
.JPG)
.JPG)
.JPG)
.JPG)
.JPG)
Model Rating
| Type | Stereo power amplifier | ||||||||||||
| Continuous average power (20 Hz to 20 kHz Strain rate 0.02%) |
|
||||||||||||
| Total harmonic distortion factor |
|
||||||||||||
| IM Distortion Factor (EIA) | 0.01% | ||||||||||||
| Frequency characteristic | 20 Hz ~ 20 kHz + 0 -0.2 dB (Continuous Average Output, Level Control MAX) 0.5 Hz ~ 250 kHz + 0 -3dB (at 1W Output, Level Control MAX) 0.5 Hz ~ 150 kHz + 0 -3dB (Level Control -6dB at 1W Output) |
||||||||||||
| Gain | 27.8 dB (stereo specification) 33.8 dB (monaural specification) |
||||||||||||
| Load impedance | Stereo specification : 1 Ω ~ 16 Ω Monaural specification : 2 Ω ~ 16 Ω |
||||||||||||
| Damping factor (EIA 50Hz) |
Stereo specification : 300 Monaural specification : 150 |
||||||||||||
| Input sensitivity |
|
||||||||||||
| Input impedance | 20k Ω unbalance 600 Ω equilibrium |
||||||||||||
| S/N (A correction) |
|
||||||||||||
| Subsonic filter | 10 Hz, -12dB/oct. | ||||||||||||
| Output meter |
|
||||||||||||
| Semiconductor used | Transistor : 90 FET : 8 IC : 36 Diode : 104 units LED : 8 pcs |
||||||||||||
| Power supply voltage | AC100V/117V/220V/240V, 50Hz/60Hz | ||||||||||||
| Power consumption (Normal Load Imp. Operation) |
165W (no input) 1100W (Electrical Appliance and Material Control Law) 1100W (at 8 Ω load rated output) |
||||||||||||
| External dimensions | Width 480x Height 232 (Including Legs) x Depth 476 mm | ||||||||||||
| Weight | 38.5kg | ||||||||||||
| Sold Separately | Persimmon / Wood Panel A-14 (Set with mounting bracket, ¥ 16,000) Heat Dissipation Fan O-81 (set, ¥ 8,000) |