Audio Database

The

DENON PMA-750
69,800yen(around the 1981 time)

Description
@
The amplifier which realized dynamic distortion 0 unreturned [ of 0dB ], and the Integrated Amplifier which carries a super-broadband super equalizer.

Circuit composition consists of a real drive circuit, amplifier of a direct DS system which carries a direct A system unreturned [ of 0dB ], and a MC/MM super equalizer.
This basic circuit has the same composition as PMA-770 which is an upper model.

Furthermore, one has adopted as all the signal courses of a speaker output terminal the Capacitor-Less composition between which it is not placed by the coupling capacitor from MC input terminal.

The MC/MM super equalizer is carried and the broadband characteristic of 20Hz-100kHz}0.2dB is realized.
Composition consists of the NF form direct-current amplifier and CR form equalizing filter by newly developed low noise dual FET, and the first rank serves as dual FET differential amplification of the direct direct-current servo system.

The power amplifier part has adopted the amplifier unreturned [ of 0dB ].
By this system, static distortion produced by the magnification characteristic that a power transistor is non-linear is driven in to the domain of zero according to the effect of a direct DS circuit, and high-quality sound-ization is attained.
Circuit composition was used as the 3 steps of differential current mirror by first rank low noise FET, by the complimentary emitter-follower, attained low impedance-ization and has separated it completely with the electric power magnification stage. High speed-ization of a signal is realized, while using an electric power magnification stage as the push pull output stage by a high-speed power transistor and aiming at improvement in each characteristic.

A zero crossing linear bias circuit original with DENON is carried in an output stage, generating of the switching distortion by cutoff of a power transistor is banished, and the quality of Class-A amplifier and efficient and high-output coexistence of Class B amplifier are aimed at.

The real drive circuit which reduces distorted generating of the amplifier at the time of speaker mounting is carried.
Thereby, by the load resistance of the speaker which changes with frequency, phase difference arises between voltage and current, it stops having made distortion increase, and distortion is reduced to 50 by about 1/near speaker fo.

The construction in a chassis is considering it as the layout which separated each section of equalizer amplifier and power amplifier, and is suppressing the mutual intervention.

Tone control, the Subsonic Filter, the loudness control switch, and the Rec out selector are carried.
Moreover, the direct couple switch and the mode switch in which a stereo reverse monophonic play is possible are carried.

The high-speed protection circuit is built in.


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, 20Hz - 20kHz)
100W+100W (4ohms)
80W+80W (8ohms)
Input sensitivity/impedance 150mV/47kohm
THD (20Hz - 20kHz, Output-power-3dB o'clock) 0.005% or less
Cross modulation distortion
(at the time of a 60Hz:7kHz=4:1 and Output-power equivalent amplitude output)
0.002% or less
Output bandwidth (IHF, both ch(es) drive, THD 0.035%) 5Hz - 100kHz
Frequency response (at the time of 1W output) 1Hz-250kHz+0 -3 dB
Output load impedance (1kHz) 0.08ohm
Output terminal Speaker AorB: 4ohms - 16ohms
Speaker A+B: 8ohm-16ohm
Headphone: 310mW/eight ohms
<Preamplifier part (Input sensitivity/impedance is removed and it is Phono in ->Rec out)>
Circuit system The super equalizer system by a direct direct-current servo
Input sensitivity/impedance Phono MM: 2.5mV/47kohm
Phono MC: 0.25mV/100 ohms
Tuner, Aux, Tape:150mV/47kohm
The maximum except take-off/Output power 10V/150mV
RIAA deflection (MC/MM) 20Hz-100kHz}0.2dB
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:88dB
Phono MC:72dB
Tuner, Aux, Tape: 110dB (at the time of a 150mV input)
Tone control Bass: }8dB (100Hz)
Treble: }8dB (10kHz)
Subsonic Filter 18Hz, 6 dB/oct
Loudness characteristic Low-pass: +7dB (100Hz)
High region: +6dB (10kHz)
Power source AC100V, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law) 200W
Dimensions Width 434x height 132x depth of 407mm
Weight 12kg