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Monarch SA-450 amplifier
Lower priced audio amplifier from the 1960's with nice specs, good design and very good sound.
This amp has a very nice, slim and good design, has a good look and is well constructed.
It was cheaper at the time but certainly as good as the most expensive competitors
of exclusive brands like the Luxman SQ700, the Sansui AU101, the Akai AA5210,
and the Kenwood KA4000 and many more.
Front detail ^
Click here to download the usermanual in ZIP format
Front detail ^
Manufacturer: Monarch (Monacor in Germany)
Type: Integrated amplifier
Year of construction: 1969 - 1972
Made in: Japan
Color: front black, wooden case
Power consumption: 60 W max.
Dimensions (WxHxD): 345 x 95 x 240 mm
Weight: 6 kg
Original price approx: ~275 DM
Phono MM: 3 mV
Phono ceramics: 150 mV
Tuner: 300 mV
AUX: 300 mV
Tape Play 300 mV
Connections for 1 pair of speakers
Continuous power RMS:
8 ohms: 2x 10 Watts
4 ohms: 2x 12 Watts
8 ohms: 2x 15 Watts
4 ohms: 2x 18 Watts
Total harmonic distortion at RMS: 1% at 8 ohms
Damping factor: 25
Frequency response: 20 - 20,000 Hz
Signal to noise ratio:
Phono: 60 dB
High level: 75 dB
Bass: ± 10 dB at 100 Hz
Treble: ± 10 dB at 10 kHz
High Filter: yes
Slider for balance, bass, treble
Mono / stereo switch
There were more than one version issued of this amp. The first version is with early transistors and driver transformers.
The second version is more modern and is OTL with semi-complementary assymetric output stage.
The schematic diagram of this amp is very common, like other brands have issued amps with similar schematic diagram,
the Luxman SQ700, the Sansui AU101, the Kenwood KA2000, are examples.
The schematic is of the first version. the photo's are of the 2nd version.
Click here to download the schematic diagram in PDF format
Amplifier board copper side 2nd version ^
Amplifier board 2nd version, not updated ^
Updating this amp is very rewarding:
Most Towa electrolytic capacitors are out of specs and should be replaced all over the amplifier.
Updating the power supply section is a must as this section is not up to modern standards anymore.
Apply power-supply star topology.
Replace the tiny power supply diodes for 100V 3A diodes.
Some transistors in the pre-amp section can get quite noisy, as the 2SC372 on pcb main board in one channel
produced quite some hiss, use BC550C or equivalent.
Set the power transformer to 240 V line voltage when you are in Europe, the used power transformer will break down
as its not designed for Europe's today 230+ Voltage in the standard selected 220V position.
Power transistor ^
Pilot light ^
Monacor 2nd version with tuner ^
This amplifier was also sold by Dixons in some European countries, such as the UK, under the name PrinzSound SA-1001 ^
The sound is very good, the 2nd version has more power.
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© PE1MMK Hans Hilberink, last update: 18-09-2019.