Marantz Model1150

Commentary

This is a pre-main amplifier that has been polished over time with an emphasis on listening quality in addition to physical characteristics.

All stages of the push-pull drive are L circuit directly connected to all stages of the push-pull drive. The output-stage uses the inverted Darlington method. complimentary service
The power supply unit capacitor uses an internal tandem with very small plus / minus capacitance deviation, reducing distortion in the high frequency range and improving stability.

The equalizer amplifier section uses a 3-stage direct-coupled NF type circuit that uses differential amplification for the input.
This circuit consists of a set of differential input transistors, a constant current source, a high-gain amplifier stage, and a stabilized + - power supply, allowing a wide range of cartridges to be used without overloading.
In addition, 100% DC feedback improves amplifier stability.

The tone amplifier section uses four transistors for each of the left and right channels, and consists of two stages of Darlington connection.
This circuit can be adjusted in three stages (bass, mid and treble) by means of independent sliding knobs on the left and right sides. Moreover, the range of influence of the tone control can be shifted to 250 Hz or less in the low range and to 4 kHz in the high range by operating the turnover switch.
Also, if the tone switch is turned out, the signal can bypass the tone control circuit and is connected to the pre-out while maintaining the flat characteristics.

Equipped with high, low, and subsonic active filter circuits.
When the front panel pushbutton is pressed, the corresponding filter element is connected to the feedback circuit of the amplifier, resulting in a roll-off of 12dB/oct at 10 Hz, 30 Hz and 9 kHz.

A PEP (Pure Electronic Protection Device) circuit is used for the protection circuit to protect the power transistor from excessive current and voltage caused by a sudden load short-circuit. The protection circuit is also equipped with a temperature compensation circuit to ensure proper operation even under extreme temperature conditions. The control circuit elements are perfectly Darlington connected.
In addition, there is a built-in speaker protection relay to protect the speakers, which is also a delay circuit that disconnects the switch for approximately four seconds after the power switch is turned on.

There is also a dubbing jack on the front panel so you can connect it without removing it from the rack or shelf.
When you plug in the Dubbing in jack, the Tape2in jack is automatically disconnected, and the Dubbing out jack and Tape2out jack are connected in parallel so that you can record to three tape recorders simultaneously and dubbing from Tape1 to one of the other and vice versa.
In addition, any tape recorder can be monitored at any time by operating the monitor switch.

The cabinet was sold separately and there were 2 types, mahogany and walnut.
There was also an optional rack mount adapter.

Model Rating

Type	Pre-main amplifier
Rated Output (20 Hz to 20 kHz, Both Channel Drive)	80W + 80W (8 Ω)
Frequency characteristic	20 Hz to 20 kHz ± 1.0 dB
Total harmonic distortion rate (20 Hz to 20 kHz)	Not more than 0.1%
Intermodulation distortion factor (20 Hz to 20 kHz)	Not more than 0.15%
Power band wiz	7 Hz to 45 kHz
Damping factor	45 or More (8 Ω Load)
Gain	Phono → preamplifier output : 58 dB Phono → Recording output : 40 dB High level → preamplifier output : 18 dB
Input impedance	Phono : 47k Ω High level : 60k Ω
Input sensitivity	Phono:1.8mV Aux:180mV
Phono input equivalent noise	1.0 μ V (Input Conversion Value)
Filter	High:9kHz Low:30Hz Subsonic : 10 Hz
Pwer	100 VAC, 50Hz/60Hz
Power consumption	250W
External Dimensions (width and height are panel dimensions)	Width 390x Height 146x Depth 315 mm
Weight	15kg
Sold Separately	Mahogany Cabinet WC-3N (¥ 11,000) Walnut Cabinet WC-3 (¥ 5,900) Rack Mount Adapter RA-2 (¥ 5,900)