Audio Database

The

DENON PMA-730
49,800yen(around the 1982 time)

Description
 
The stereo Integrated Amplifier which carries the power amplifier unreturned [ of 0dB ], and a super equalizer.

The direct distortion servo circuit has realized the non-feedback system.
This servo circuit compares the signal (main signal + distorted ingredient) and incoming signal which are acquired from the output side, detects only a distorted ingredient, carries out phase inversion of this distorted ingredient, and adds it to an input side. Thereby, static distortion is reduced to the domain of theory top zero.
In this non-feedback system, in order not to return an output signal to an input side like a negative return (NFB) system, dynamic distortion did not occur but the features, like "simple-ized" "high-speed-izing" of the circuit can be carried out have been acquired, without being influenced by the back electromotive force of a speaker.

In order to correspond also to the speaker of low impedance, the power-source part and the electric power magnification stage are strengthened so that he may feel easy even about a 4-ohm speaker and a full power play can be performed.

The first rank uses circuit composition of a power amplifier part as a 2 steps of differential current mirror with a low noise transistor, and it attains low impedance-ization and it is making it separate it completely with an electric power amplifier by the complimentary emitter-follower.
The electric power magnification stage has push pull composition of a high-speed power transistor, and is attaining high power-ization.
The filter which cuts a harmful super-low-pass noise is built in the input unit of this power amplifier.

In order to correspond to wide-range-ization of a cartridge or power amplifier, the super equalizer is developed and carried, and the frequency response of 100kHz is realized.
The first rank considers it as the differential amplification by low noise dual FET, and the following stage consists of an op amplifier and a CR form equalizing filter, and consists of direct-current servo systems.

In order to demonstrate the engine performance of MC cartridge, while removing the input capacitor which influences sound quality greatly from MC input terminal, it is considered as a perfect Capacitor-Less to Rec out, and also high gain-ization is also performed.

Tone control, loudness control, and a Rec out selector are carried.

The high-speed protection circuit is carried.

The

Rating of a mode
Form Integrated Amplifier
<Power amplifier part>
Circuit system Unreturned [ of 0dB ] power amplifier system
Output power
(both channel drive, a sine wave continuation output)
60W+60W (4ohm-8ohm, 20Hz - 20kHz)
Input sensitivity/impedance Tuner, Tape, Aux:150mV/47kohm
THD (20Hz - 20kHz, Output-power-3dB o'clock) 0.009% or less
Cross modulation distortion (60Hz:7kHz=4:1) 0.005% or less (at the time of an Output-power equivalent amplitude output)
TIM distortion Below a measurement limit
Slew rate 150v/microsec
Output bandwidth (IHF, both ch(es) drive, THD 0.1%) 5Hz - 80kHz
Frequency response (at the time of 1W output) 4Hz-150kHz+0 -3 dB
Output load impedance (1kHz) 0.1ohm
Output terminal Speaker AorB: 4ohms - 16ohms
Speaker A+B: 8ohm-16ohm
Headphone: 230mW/eight ohms
<Preamplifier part>
Circuit system The super equalizer system by direct-current servo
Input sensitivity/impedance Phono MM: 2.5mV/47kohm
Phono MC: 0.2mV/100 ohms
The maximum except take-off/Output power 10V/150mV
RIAA deflection (MC/MM) 20Hz-100kHz±0.3dB
THD 0.002% or less (at the time of 1kHz and 8V output)
<Synthesis>
Signal to noise ratio (IHF-A, input short circuit) Phono MM:86dB
Phono MC:70dB
Tuner, Aux, Tape: 106dB
Tone control Bass: ±8dB (100Hz)
Treble: ±8dB (10kHz)
Loudness characteristic Low-pass: +7dB (100Hz)
High region: +6dB (10kHz)
Power source AC100V, 50Hz/60Hz
Power consumption
(Electrical Appliance and Material Control Law)
150W
Dimensions Width 434x height 112x depth of 390mm
Weight 9kg