Audio Database

The

DENON PMA-950
150,000yen(around the 1981 time)

Description
 
The Integrated Amplifier which pursued whether they were efficient-izing and high output while harnessing the quality of Class-A operation.

In order to realize the almost same body size as the equivalent amplifier of Class B operation with loading by Class-A power amplifier, the real bias circuit is carried.
A real bias circuit is the same principle as POA-3000 or PMA-970, and the method of preceding bias current and making it recover from signal current is used for it. As compared with the conventional system that this supplies much bias current at the time of a non-signal, about 1/of power consumption improvements of 10 are realized.

The circuit of the power amplifier part is constituted from a low-noise FET parallel differential amplification + direct direct-current servo and a pre-driver stage of the 3 steps of differential amplification current mirror cascode bootstrap output which has powerful drive capability in the 2nd step by the first rank.

The real drive circuit is carried and the voltage at the time of speaker real load and the phase difference of current are improved.
In this circuit, it adds to parallel use of a power transistor paying attention to operation of the amplifier at the time of speaker mounting,When the real drive line by an electronic device is installed in a protection circuit, lack of the signal at the time of the Taishin number is canceled and a common speaker system is connected, near fo of the Oide power, distortion is improved about 1-/50.

The equalizer circuit consists of the NF type direct-current amplifier and CR type equalizing filters by newly developed low-noise dual FET, and the first rank is 4 parallel differential amplification circuit of direct direct-current servo system dual FET, and is planning a low-noise and Quantity SN.
Moreover, the cascode bootstrap circuit which does not receive the influence of input impedance in the first rank of an equalizer is adopted, and distortion is reduced.

The original direct direct-current servo circuit where stability is high was carried, and capacitor removal is realized from all the signal courses of resulting in SP output from MC input.

The tone control part consists of only passive devices required for tone control, and has the simple composition of having removed the mass capacitor harmful to sound quality from the signal course, by including it in some power amplifier.
Moreover, it has the structure where the composition of a main circuit is not affected at the time of a tone defeat, either.

A large-sized toroidal transformer and a 44,000-micro F block capacitor are carried in the power-source part.
Furthermore, in order to supply current to the right-and-left channel of a power stage on the same conditions, the layout of a power current pure radiation construction system is adopted, and shortening of wiring is also attained.
Moreover, sufficient shield for the power transformer circumference is given, and the influence on a signal system circuit and the influence on external apparatus are suppressed.

The high-speed protection circuit which served as muting operation at the time of power switch ON is carried.

The headphone jack which carries the impedance change function of High/Low is equipped.

The function of a Subsonic Filter, loudness control and a muting function, a direct couple switch, etc. is carried.

The side wood of the Brazi LeAnn rosewood tone is attached to the side.

Rear
Internal

Rating of a mode
Form Integrated Amplifier
<Power amplifier part>
Circuit system Direct direct-current servo system Denon class A
Output power (both channel drive, a sine wave continuation output) 80W+80W (8 ohms, 20Hz - 20kHz)
100W+100W (4 ohms, 1kHz)
Input sensitivity/impedance 150mV/40kohm
THD (at the time of 60Hz:7kHz=4:1 and an Output power) 0.004% or less
Output bandwidth (IHF, both ch(es) drive) 5Hz - 100kHz (THD 0.03%)
Frequency response (at the time of 1W output) 1Hz-250kHz+0 -3 dB
Signal to noise ratio (IHF-A) 110dB
Output load impedance 0.1ohm or less
Slew rate 250v/microsecond
<Preamplifier part (equalizer amplifier)>
Input sensitivity/impedance Phono1, 2 MM:2.5mV /, 47kohm
Phono1, 2 MC: 125 microvolts/100 ohms
Tuner, AUX, Tape1, 2:150mV/40kohm
The maximum except take-off/Output power 10V/150mV
RIAA deflection 20Hz-100kHz±0.2dB (MM and MC)
THD 0.001% (1kHz, output 8 V:00)
<Synthesis>
Signal to noise ratio (IHF-A, input short circuit) Phono1, 2 MM: 90dB
Phono1, 2 MC: 75dB (at the time of a 250-microvolt input)
Tuner, AUX, Tape1, 2:110dB
Tone control bass: ±8dB (100Hz)
treble: ±8dB (10kHz)
Subsonic Filter 18Hz, 6 dB/oct
Loudness control 100Hz : +7dB, 10kHz : +6dB
Muting -20dB
Power supply voltage AC100V, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law) 265W
Dimensions Width 470x height 140x depth of 410mm
Weight 15kg