Audio Database

PM-5
Commentary

Pre-main amplifier capable of switching between pure class A and class AB.

In addition to pure A-class 20W/ch, AB-class 80W/ch can be switched. Moreover, in order to raise the quality of AB-class to the level of pure A-class, a high-speed high-fT transistor with a high cut-off frequency of 90 MHz is adopted in the power stage, eliminating the switching distortion that is a defect of AB-class to the limit.

The PM-5 adopts a complete push-pull DC amplifier configuration in all stages to eliminate TIM distortion from every corner of the amplifier, thereby improving the bare characteristics.
Transient cross-modulation distortion and static characteristics are improved without applying a large amount of NFB.

In order to improve the stable operation of the power transistor, a newly developed heat pipe system has been adopted for the heat radiation mechanism. Since heat is out of the circuit and cooled by a radiator, the transistor can be placed in an ideal position, simplifying the circuit and reducing distortion.
The power supply section is equipped with a large-capacity capacitor developed for audio equipment and a compact high-power transformer filled with a special resin for heat resistance.

The phono amplifier block is designed with low distortion and high S/N ratio by using transistors lavishly.
In addition, a straight DC circuit connecting the phono amplifier directly to the power stage is incorporated to improve the quality of disc playback.
In addition, the phono amplifier incorporates a high-precision MC head amplifier and subsonic circuit.
The subsonic function works only for the equalizer to simplify other functions.

The tone control is adjustable by ± 8 dB from 100 Hz to 10 kHz. The balance can be adjusted independently on the left and right sides. Moreover, the use of high precision volume realizes a flat response at the midpoint of the knob.
It is also equipped with a loudness control that compensates for the low and high frequencies.

The center of the front panel is equipped with a full-scale peak power meter.
Unlike bar display, both pure A class and AB class LED display power as points, so clear and accurate output can be directly read.
Under the meter, there are various functions such as a dubbing circuit that enables mutual recording from deck to deck, and a speaker selector switch that enables listening comparison between two speakers and simultaneous playback.

Model Rating
Type Stereo pre-main amplifier
Rated output
(20 Hz to 20 kHz, both channels driven simultaneously)
80W + 80W (8 Ω, Class AB)
20W + 20W (8 Ω, pure Class A)
Total harmonic distortion factor 0.015% or Less (Effective Output, 20 Hz to 20 kHz, 8 Ω Load)
Cross modulation distortion factor 0.015% or Less ((60 Hz : 70 kHz = 4 : 1, effective output, 8 Ω)
Frequency characteristic + 0, -0.2 dB (20 Hz to 20 kHz)
5 Hz to 100 kHz (+ 0, -2dB)
Damping factor 100 or More (8 Ω Load, 1 kHz)
Input Sensitivity / Impedance phono1 mm : 2.2mV/47k Ω
phono2 mm : 2.2mV/47k Ω
phono2 mc : 200 μ V/75 Ω
TAPE, TUNER, AUX : 150mV/40k Ω
Rated Output / Impedance TAPE OUT : 150mV/600 Ω
RIAA deviation ± 0.2 dB (20 Hz to 20 kHz)
Tone control characteristics ± 8 dB (Low Frequency 100 Hz)
± 8 dB (high frequency 10 kHz)
S/N ratio (IHF-A) phono MM:86dB
phono MC:68dB
TAPE, TUNER, AUX : 108 dB
Phono maximum allowable input MM:220mV(1kHz)
MC:20mV(1kHz)
Rated power consumption Electrical Appliance and Material Control Law : 200W
Pwer 100 V, 50/60Hz
External dimensions Width 416x Height 146x Depth 332 mm
Weight 13kg