Marantz MA-5
¥ 100,000 (released in 1979)
Commentary
Monaural power amplifier capable of switching between class A and class AB operation.
The circuit configuration is a Low-TIM design, and it is a 3-stage Darlington circuit with a power amplification stage which is a parallel push-pull type of super high-fT transistor excellent in high-frequency characteristics and switching characteristics.
A large transformer and 22,000 μ Fx2 large audio capacitor are used for the power supply.
The main amplifier uses a specially selected Meiler capacitor for phase correction.
In addition, three boards (power supply board, relay circuit board, and main board) are made into a joint structure, and the power supply for the pre-stage amplifier of the main amplifier is made into a separate board. In order to improve the sound quality, priority is given to the pattern of the signal system.
Equipped with a temperature-sensitive protection circuit, a temperature sensor detects when the heat sink reaches an abnormal temperature and a high-speed relay circuit protects each circuit.
The input terminal can be either an AC couple or a DC couple, and each has a different system of direct input terminals.
The terminal uses a gold plated terminal with less trouble of contact failure.
A peak level meter using LED is used for the level meter.
Display up to + 4 dB 75W at A-class operation, and up to + 4 dB 300W at AB-class operation.
Switching between class A operation and class AB operation is possible.
Switching is performed by operating the switch on the rear panel.
Instead of the conventional bar graph display, the power meter displays the output as a point with LED.
Uses a high-speed response protection circuit that directly detects the temperature of the heat sink with a thermal sensor.
AC amplifier and DC amplifier can be selected. Moreover, it is equipped with a gold-plated direct input terminal that does not pass through SW and has little sound quality degradation.
The power switch and gain control are housed in a traditional sub-panel.
.JPG)
Model Rating
| Type | Monaural power amplifier |
| Rated Output (20 Hz ~ 20 kHz) | 120W (8 Ω, Class AB Drive) 150W (4 Ω, Class AB Drive) 30W (8 Ω, pure Class A drive) |
| Total harmonic distortion factor | 0.01% (8 Ω, 20 Hz to 20 kHz) |
| Cross modulation distortion factor | 0.01% |
| Frequency characteristic | 20 Hz ~ 20 kHz + 0 -0.2 dB DC ~ 100 kHz + 0 -1dB |
| Input Sensitivity / Impedance | 1.5V/30k Ω |
| Damping factor | 100 or More (8 Ω Load) |
| Residual noise (IHF-A curve) | 0.034mV |
| Pwer | 100 VAC, 50/60Hz |
| Power consumption | 150W |
| External dimensions | Width 208x Height 146x Depth 334 mm |
| Weight | 10kg |