本帖最後由 kk_ho 於 2010-6-20 22:10 編輯
DENON POA8000, what happen?
Monophonic power amplifier which adopted the DENON non-feedback system.
In POA-8000, it turned around from the system which negates dynamic distortion, and the non-feedback system which does not generate dynamic distortion from the beginning is adopted.
In a non-feedback system, the incoming signal is amplified only to one way and the signal transmission and the magnification system which transient response distortion does not generate probably are adopted. Distortion and noise which were generated by the magnification system are removed in the distorted removal circuit.
Since the circuit composition of POA-8000 is the composition that the main magnification system has neither a phase compensation circuit nor beta circuit and can reduce a magnification stage by half, the main magnification system amplified the signal in real time from the input to the output, and also since [ which does not have return ] one-way traffic, it did not produce transitional distortion, either, but has acquired the outstanding dynamic characteristic.
A distorted removal circuit carries a voltage type in the first rank, and carries the electric power type in the final stage.
This distorted removal circuit compares the incoming signal and output signal of magnification system amplifier, and has detected all the ingredients other than an incoming signal as a magnification element being distorted. Next, after making into negative phase the distorted ingredient taken out here, it amplifies so that it may become equivalent at the mixing point of the distorted ingredient by the side of an output, and the main magnification output circuit. And the completely same distorted ingredient (negative phase) as the distorted ingredient by the side of an output is added to the output side.
In this circuit, it is distorted, and also it considered that all ingredients other than an incoming signal are distorted, and the dynamic change of an amplification degree, a frequency response, the drift of a operating point, noise, etc. has removed them.
The basic circuit is constituted centering on a three-step Darlington power stage, and is the composition of [ all ] the unreturned amplifier of the complimentary Class-A push pull circuit from the first rank to the last stage.
The first rank is the complimentary push pull composition of FET of low noise and high gain, and performs unreturned voltage magnification by a distortion removal circuit once here. This output lets a high ft small signal transistor emitter-follower circuit pass, is formed into low impedance and sent into a pre-driver stage.
The pre-driver stage has simple circuit composition of the one-step magnification by the complimentary push pull. 4 parallel use of the high proof-pressure type transistor of ft130MHz, Pc1W, and VCEO200V is carried out, the current burden of each transistor is eased, and it is made to operate on best conditions here. Moreover, the resistance which determines the profit of this stage used ±1% of the accuracy error, and the high precision metal vapor deposition type with a temperature coefficient of ±50 ppm, and has secured the characteristic that stability is high.
It is a cascode emitter-follower circuit with ft400MHz and two small signal transistors of a high linearity from which a power stage is three-step Darlington composition and which the fast driver stage surpassed in the high region characteristic. A second driver is a parallel push pull circuit of four transistors. The last output stage has composition of 6 parallel push pull circuit by 12 Pc150W high-speed power transistors.
The glass epoxy radical board of 140micro of Copper-foil thickness which made circuit resistance the minimum, and the oxygen-free-copper board are used for the circuit board of a power transistor part. This is suppressing the signal transmission loss by the circuit manual training at the time of high output.
The digital display carried in the front of a front usually carries the speaker referential function of SP1orSP2 at the time of operation with the muting counter function counted down from 7 to 0 with the power source on.
Furthermore, the self-diagnostics function is carried, and it confirms whether the set is operating stably, it expresses as the English character (E-7-0) which had abnormalities coded, and self-diagnostics of the error part is carried out. In the display of E-0, by an abnormal temperature rise and the display of E-3, as it said that the middle point electric potential of a main circuit was unusual, it is displayed. An output relay is intercepted by the detector circuit in an instant at the time of such abnormalities and the mistaken use.
The output level meter of a peak indicating type is carried.
Even the -50dB-+5dB is indicated by a peak by the display of dB and WATT (0dB=200W/8 ohm). Moreover, the peak level of the output serves as the peak hold facility which the red light emitting diode embedded to the core of meter turns on for several seconds, if an instant also exceeds an Output power.
In the power-source part, the secondary carries the large-sized transformer of four winding wire, and supplies high pressure and Takayasu constant current to the power part (160V) and the voltage amplifier (220V) at it.
Furthermore, the power-source part consists of adviser plates which adopted a high proof pressure and a mass electrolytic condenser, and a 1.5mm brass plate.
The 15mm thick sheet glass of a high-density cut is adopted as a face of panel. Moreover, 6mm thickness smoked glass is adopted as upper surface glass covering.
The top plate is equipped with the ventilator which carried out cutting processing of the extrusion aluminum material which performed black alumite processing.
Alumite processing is given to the side panel with the escutcheon bar at champagne gold.
The thing of 60mm in diameter aluminum shaving appearance is adopted as an insulator.
.JPG)
Form Monophonic power amplifier
Music output 320W (8ohms)
Output power (sine wave continuation, 20Hz - 20kHz) 200W (8ohms)
THD (sine wave continuation, 20Hz - 20kHz) 0.003% or less (8ohms)
Cross modulation distortion
(at the time of 60Hz:7kHz=4:1 and an Output power) 0.005% or less
Output bandwidth (THD 0.01%) 5Hz - 100kHz
Input sensitivity/input impedance 1V/50kohm
Output load impedance (1kHz) 0.1ohm or less
Signal to noise ratio (IHF-A) 120dB or more
Frequency response (at the time of 1W output) 1Hz-200kHz+0dB-3dB
Output terminal Two lines
Subsonic-Filter characteristic 16Hz, 6 dB/oct
Slew rate ±380v/microsec
<Level meter characteristic>
Indicating type Peak value indicating type level meter
Indicating range - 50dB - +5dB (0dB=200W/8 ohm)
Frequency response 10Hz-100kHz±3dB
An attached function Output-power peak hold display
<Digital display function>
Muting display Countdown to the initial value 7->0
Speaker display SP1, SP2
Self-diagnostics function A main circuit and distorted removal circuit, the diagnosis of
operation at the time of an abnormal temperature rise
<Others>
Power supply voltage AC100V, 50Hz/60Hz
Power consumption 330W (Electrical Appliance and Material Control Law)
160W (at the time of a non-signal)
Dimensions Width 310x height 188x depth of 462mm
(it is an included about the height of knobs and a base)
Weight 22kg |
[複製鏈接]
收藏
轉播
分享
淘帖
頂
踩
樓主
