Audio Database

The

DENON PMA-550
89,800yen(around the 1980 time)

Description
 
The Integrated Amplifier which carries a super equalizer in order to utilize the engine performance of a cartridge.

Basic composition has 2 amplifier composition of MC/MM super equalizer amplifier and non switching A power amplifier, and is considered as the perfect direct-current composition which does not use a coupling capacitor for a signal course from MC input terminal even to SP output terminal in addition to this simple composition.
This perfect Capacitor-Less composition has realized the direct direct-current servo system of DENON by carrying in an equalizer and both the amplifier of power, shut out direct-current drift and has realized original sound quality of direct-current composition amplifier.

In order to aim at correspondence to the cartridge in which a broadband play is possible, the super equalizer is carried in the equalizer part.
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 parallel differential amplification of dual FET of a direct direct-current servo system.
This has gained the high gain which is overly equal to the head amplifier only for MC in addition to wide-range-izing. Moreover, MC cartridge of a low output is also supported.
Moreover, the dual listening mechanism of a cartridge is carried and not only change use of MC/MM but the comparison audition of two MC or two MM can be operated with the push button of the front panel.

Direct direct-current servo system high gain non switching A power amplifier is carried in the power amplifier part.
Composition is the low impedance buffer amplifier by a first rank low noise FET parallel differential +IC high-speed operation (operation) amplifier,It is a driver stage of a 3 steps of differential current mirror, and an output stage of the high-speed power transistor 2 parallel push pull, and the direct direct-current servo is applied to the first rank of buffer amplifier from the output terminal of power amplifier at overalls. This is aiming at the characteristic improvement of amplifier, such as Sadamu a high speed, high gain and Takayasu, and a low distortion.
Moreover, while carrying the high speed thermal feedback circuit in the zero crossing linear bias circuit original with DENON and banishing switching distortion which is a merit of non switching in a bias circuit, high operational stability is realized.

Real-time tone control is carried in the tone circuit.
It consisted of only passive devices required for tone control, and the distortion of the tone circuit itself and the problem of S/N are solved by not giving an amplifying function.

Leakage flux, the large-sized toroidal transformer which thought the rate of voltage fluctuation as important, and a 44,000-micro F block capacitor are carried in the power-source part.
This power-source part has been arranged at the center of the power amplifier part of right-and-left independence, and has adopted the layout of the power current pure radiation construction system which is a curtate distance about wiring and makes L/Rch the equal distance.

Functions, such as a direct couple switch, a Rec out off function, an effective equalizer Subsonic Filter only at the time of a record play, and loudness control, are carried.

Rear

Rating of a mode
Form Integrated Amplifier
<Power amplifier part (Tuner in->SP out)>
Output power (both channel drive, a sine wave continuation output, 20Hz - 20kHz) 140W+140W (4ohms)
100W+100W (8ohms)
Input sensitivity/impedance 150mV/40kohm
THD (20Hz - 20kHz, Output-power-3dB) 0.005% or less
Cross modulation distortion (an equivalent for 60Hz:7kHz=4:1 and an Output power) 0.008% or less
Output bandwidth (IHF, both ch(es) drive) 5Hz - 400kHz (THD0.035%)
Frequency response (at the time of 1W output) 1Hz-400kHz+0 -3 dB
Output load impedance (1kHz) 0.1ohm
Speaker output AorB: 4ohms - 16ohms
A+B: 8ohm-16ohm
<Preamplifier part (Input sensitivity/impedance is removed and it is Phono in->Rec out)>
Input sensitivity/impedance Phono MM: 2.5mV/50kohm
Phono MC1, 2:0.125 mV/100 ohms
Tuner, AUX, Tape:150mV/40kohm
The maximum except take-off/Output power 10V/150mV
RIAA deflection (MM, MC) 20Hz-100kHz±0.2dB
THD (at the time of 1kHz and 9V output) 0.001% or less
<Synthesis>
Signal to noise ratio (IHF-A, input short circuit) Phono MM: 90dB (at the time of a 2.5mV input)
Phono MC: 73dB (at the time of a 0.25mV input)
Tuner, AUX, Tape: 108dB
Tone control Bass: ±8dB (100Hz)
Treble: ±8dB (10kHz)
Subsonic Filter 18Hz, 6 dB/oct
Loudness control 100Hz : +7dB, 10kHz : +6dB
Power supply voltage AC100V, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law) 255W
Dimensions Width 434x height 132x depth of 407mm
Weight 13.5kg