General:

Marantz amplifier made around 1974 that used to be a competitor to the Luxman amplifiers, but was cheaper as the Luxmans and Sansui's.

 

 

Front ^

 

Back ^

 

Special futures:

This is a very nice solid state amplifier, with 30 Watts RMS per channel power capacity.
The schematic diagram shows a very traditional setup amplifier, with not very modern technology used at the time,
The Sansui's and certainly the Luxmans were much more advanced in their used electronic technology.

It has that midrange tone knob together with traditional bass & high, just like the Sansui's had at the time.

The amp is rugged built and has the typical Marantz looks and is virtually indestructable, a real work horse.

 

User Manual:

Not yet available

 

Schematic:

Click here to download the service manual in PDF format

 

Intergated amplifier with single power supply rail up to +70 Volts, - to ground.
Assymetric power supply, output capacitors, complementary drivers, semi-complemetary final output stage.
Vertical pcb power-amp section. All AC-capacitor-coupled stages from pre-amp to power-amp section.

 

Power amp component side ^

 

Power amp pcb copper side ^

 

 

 

Typical power amplifier build as Marantz did for several years. ^

 

Modifications:

Many capacitors must be exchanged, some transistors may produce noise, corrosion of the chassis is often an issue.

Set the amplifier mains to 240V in Europe due to the detrimental Voltage change in EU.

The main capacitor of the power supply is important in this kind of design: if exchanged, choose a good one of high capacity
and proper voltage.

 

Bottom view ^

 

Restore of the power amp ^

 

pre-amp section. ^

 

RIAA amp section. ^

 

The Hitachi power transistors, Marantz used Toshiba, Motorola, Ti and Fairchild as well ^

 

Alignment after the repair/restore, setting bias and DC-offset ^

 

Sound:

Good sound amplifier, well built and good parts used.