Marantz PM-6a
¥ 160,000 (around 1981)
Commentary
Pre-main amplifier equipped with QuarterA system.
In QuaterA, the bias current is fixed until a certain power level (30W for PM-6a) is reached and the operation is fully pure class A. When the power level is exceeded (from 30W to 120W for PM-6a), the operation is automatically switched to class AB.
The switching is done purely electronically using a high-speed switching circuit newly developed by Marantz.
The power amplifier section equipped with this QuaterA system is fully push-pull DC configuration with built-in DC-servo circuit, and excellent characteristics are obtained by the Low-TIM design that reduces transient distortion by improving bare characteristics and reducing NFB of the amplifier.
Dedicated to the MC cartridge, it is equipped with a genuine headphone amplifier with 13 transistors per channel from the 4-parallel push-pull input stage with ultra-low noise transistors to the SEPP configuration output stage.
The phono amplifier section uses Marantz's unique push-pull circuit configuration for all stages to achieve high SN and high dynamic range. In addition, the equalizer element uses a metal-coated resistor with an error of 1% and a polypropylene capacitor with an error of 2% to achieve excellent characteristics.
Equipped with a TONE switch that can bypass the entire tone amplifier circuit.
In the Tone Out position, the output of the flat amplifier is directly connected to the power amplifier, so you can enjoy a purer quality.
The power supply section is equipped with a small large-capacity power transformer with improved heat resistance by filling with special resin, and a super audio condenser of 22,000 μ Fx2 that is carefully selected for sound quality.
In addition, a heat pipe system with high heat radiation effect is adopted, and stable operation is obtained even in pure A class which consumes a large current.
It is equipped with two phono inputs, of which Phono1 is equipped with 27k Ω, 47k Ω and 100k Ω MM load clock in addition to the MC head amplifier position.
In addition, it is equipped with functions such as a tape copy switch that allows two decks to dub each other, two levels of loudness, and independent tone control on both sides.
There was a mahogany cabinet sold separately.
Model Rating
| Type | Stereo pre-main amplifier |
| Rated Output (20 Hz ~ 20 kHz) | 120W + 120W (8 Ω) |
| Total harmonic distortion rate (20 Hz to 20 kHz) | 0.015% or Less (at Rated Output) |
| Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) | 0.015% or Less (at Rated Output) |
| Frequency characteristic | 5 Hz ~ 100 kHz + 0 -2dB |
| RIAA deviation | 20 Hz to 20 kHz ± 0.2 dB |
| Signal-to-noise ratio (IHF-A) | Phono MM:86dB Phono MC:68dB Tape, Tuner, AUX : 110 dB |
| Rated power consumption | 350W |
| External dimensions | Width 416x Height 146x Depth 332 mm |
| Weight | 16.0kg |
| Sold Separately | Wood Cabinet WC-77N (¥ 12,500) |