Marantz 140 Manual

The Marantz 140 is a high-performance stereo amplifier known for its exceptional audio quality and robust construction. Featuring 70 watts per channel RMS power output, dual mono design, high-current capability, and premium components, this amplifier delivers pristine sound reproduction for audiophile systems. Below are key sections covering specifications, installation, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Dual mono power amplifier design, gold-plated RCA inputs, heavy-duty speaker terminals, aluminum front panel, power meters, and protection circuitry.

Feature	Description
Power Output	70 watts per channel RMS (8 ohms)
Frequency Response	20Hz - 20kHz ±0.5dB
Total Harmonic Distortion	<0.05% at rated power
Input Sensitivity	1.2V for rated output
Input Impedance	47k ohms
Damping Factor	>100 at 8 ohms
Speaker Terminals	Heavy-duty binding posts
Power Requirements	120V AC, 60Hz, 350W max
Dimensions	17" W × 5.5" H × 13.5" D
Weight	28 lbs

Installation

Unpack and inspect contents. Place on stable, well-ventilated surface.

1. Position amplifier: Ensure adequate ventilation space (minimum 4 inches on all sides).
2. Connect speakers: Use heavy-gauge speaker wire to binding posts.
3. Connect audio sources: Use high-quality RCA cables from preamp or source components.
4. Connect power cord: Plug into grounded AC outlet.

WARNING! Amplifier generates heat during operation; ensure proper ventilation. Use correct speaker impedance (4-16 ohms).

First-Time Setup

Power on amplifier; observe initial operation.

1. Check connections: Verify all cables are secure and properly connected.
2. Power sequence: Turn on source components first, then amplifier.
3. Volume control: Start with volume at minimum, gradually increase to desired level.
4. Monitor operation: Observe power meters and ensure normal operation.

CAUTION! Always use proper power sequence to prevent speaker damage.

Specifications

• Power Output: 70W + 70W (8 ohms, 20Hz-20kHz)
• Dynamic Power: 90W (8 ohms), 120W (4 ohms)
• THD: <0.05% (20Hz-20kHz at rated power)
• IM Distortion: <0.05%
• Signal-to-Noise Ratio: >100dB
• Inputs: 2 line-level RCA pairs
• Speaker Outputs: A/B selector, binding posts
• Protection: DC offset, thermal, short circuit
• Power Consumption: 350W maximum
• Finish: Black or silver aluminum

Controls and Connections

Front Panel: Power switch, power meters, speaker selector, input selector.

Rear Panel: AC power input, fused AC receptacle, RCA input jacks, speaker binding posts, ground terminal.

Operation: Power switch (on/off), Input selector (1/2), Speaker selector (A/B/A+B/Off), Power meters (left/right channel indicators). Protection: Automatic shutdown for overload, thermal protection, DC offset protection.

Connecting Audio Sources

Inputs: Two line-level RCA inputs. Speakers: A/B outputs with binding posts.

1. Turn off all components before connecting.
2. Connect source components to INPUT 1 or INPUT 2 using RCA cables.
3. Connect speakers to SPEAKER A or B terminals, observing polarity.
4. Ensure all connections are secure and cables are routed properly.

Tip: Use high-quality cables and keep signal cables away from power cords.

Operation Guide

Designed for high-fidelity stereo reproduction.

1. Power on: Switch amplifier on after source components.
2. Select input: Choose INPUT 1 or INPUT 2 as required.
3. Select speakers: Choose A, B, or A+B speaker outputs.
4. Monitor levels: Observe power meters for proper operation.
5. Volume control: Adjust using connected preamplifier.
6. Power off: Turn off amplifier first, then source components.

WARNING! Do not operate without proper load. Avoid shorting speaker terminals.

Maintenance

Unplug before cleaning. Use soft, dry cloth for exterior; compressed air for vents.

CAUTION! No user-serviceable parts inside. Refer servicing to qualified personnel.

Regulatory Information

FCC Part 15: Class B digital device; complies with interference limits. UL listed. Copyright © Marantz America, Inc. For support, visit www.marantz.com or contact authorized service centers.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Power cord/fuse	Check AC connection; replace fuse if blown.
No sound	Connections/selector	Verify input and speaker connections; check selector settings.
Distorted sound	Overload/impedance	Reduce volume; check speaker impedance compatibility.
Protection mode	Overload/short circuit	Turn off, check for shorts, allow cooling, restart.
Hum/buzz	Grounding/cables	Check ground connections; reroute cables away from power.

Reset: Power cycle amplifier if protection engages.

Service: Contact authorized Marantz service center for internal issues.