Marantz 1180
A stereo pre-main amplifier from Marantz emphasizing low transient intermodulation distortion and wide-band performance.
Overview
The Marantz Model 1180 is a stereo pre-main amplifier designed to minimize transient intermodulation distortion (TIM) and deliver stable, high-fidelity performance across a wide frequency range. Built with Marantz’s signature attention to DC stability and protection, it features a fully DC-coupled power amplifier section and advanced circuitry aimed at reducing phase distortion. The unit includes a tone defeat switch, loudness contour with Fletcher-Munson curve adjustment, and an independent Tape Copy circuit for dual-deck monitoring and duplication.
Specifications
| Rated output (20 Hz to 20 kHz, both channel drive) | 90W + 90W (8 Ω) 115W + 115W (4 Ω) |
| Frequency Response (20 Hz to 20 kHz) | + 0, -0.2 dB |
| Total harmonic distortion factor | 0.03% |
| Cross modulation distortion factor | 0.03% |
| Damping factor | 60 |
| Input Sensitivity / Impedance Main amplifier input | 1.5V/30k Ω |
| Input Sensitivity / Impedance Phono MM | 1.8mV/47k Ω |
| Input Sensitivity / Impedance Microphone | 1.8mV/47k Ω |
| Input Sensitivity / Impedance High level | 180mV/25k Ω |
| Rated Output / Impedance Pre Out | 1.5V/200 Ω |
| RIAA deviation (20 Hz to 20 kHz) | + / - 0.2 dB |
| Tone control characteristics Bass (100 Hz) | + / - 10 dB |
| Tone control characteristics Mid (700 Hz) | ± 6 dB |
| Tone control characteristics Treble (10 kHz) | ± 10 dB |
| Filter Low | 15 Hz, 18dB/oct. |
| Filter High | 9 kHz, 18dB/oct. |
| Power consumption | 240W (Electrical Appliance and Material Control Law) |
| Power | 100 V, 50Hz/60Hz |
| External dimensions | Width 416x Height 146x Depth 316 mm |
| Weight | 15kg |
| Standard Walnut Cabinet | WC-110 (¥ 7,000) |
| Standard Mahogany Cabinet | WC-110N (¥ 12,000) |
Design
The power section uses a pure complementary OCL parallel push-pull 3-stage Darlington circuit in a DC configuration, with low-noise components custom-made by Marantz. The first stage of the power amplifier employs a differential amplification cascode bootstrap circuit using low-noise FETs to minimize temperature and time drift. The equalizer amplifier uses a 5-transistor configuration with a first-stage differential 3-stage direct-coupled circuit and specially designed low-noise elements. A Bessel filter provides sharp 18dB/oct. roll-off at 9 kHz and 15 Hz with minimal phase distortion. The amplifier includes an ESP circuit inherited from the P510M that protects against overcurrent, overvoltage, and DC output by limiting driver signals without interrupting playback. A 4-second relay delay prevents turn-on shock, and speaker protection disconnects the output in case of transistor failure. A peak indicator aids level setting to avoid clipping, and a DC/AC amplifier selection switch is provided.
Context
The Marantz Model 1180 shares its ESP protection circuit with the P510M, indicating a direct design lineage within Marantz’s high-end amplifier family of the late 1970s.
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