Rotel RA-840B - User Manual

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Summary

Important Information

Design Philosophy and Headphone Use

Discusses design philosophy, headphone listening, and disconnecting speaker leads.

MM;MC Switch and Volume Control

Notes MM/MC switch location and volume control usage before switching or powering.

Dubbing Function

Explains tape-to-tape copying using TAPE 1 and TAPE 2 buttons.

Introduction and Setup

Introduction

Welcomes users, highlights Rotel's design and quality.

Power Supply and Connections

Provides instructions for power supply and connecting components.

Hooking Up Speakers

Connects speaker leads to "L" and "R" terminals, ensuring correct polarity.

Controls and Operation

Switches and Controls Overview

Details the functions of the power button, headphone jack, and selector buttons.

Operation Guide

Instructions for listening from turntable, CD, tuner, and playing/recording tape decks.

Hum and Noise Troubleshooting

Provides guidance on identifying and resolving hum and noise issues.

Protection Circuit

Explains the unit's protection circuit and actions for no sound output.

Voltage Selection

Information on voltage settings and compatibility for different regions.

The Rotel RA-840B/RA-840BX is a stereo integrated amplifier designed for high-fidelity audio reproduction. Its design philosophy emphasizes a "STRAIGHT LINE" loudspeaker path to minimize sound degradation from oxidation, ensuring a pure audio signal. This means that for private listening with headphones, it is necessary to disconnect the loudspeaker leads from the amplifier to maintain optimal sound quality.

Function Description

The amplifier features a range of controls and input options to manage various audio sources. The front panel includes a Power Button that turns the unit on and off, indicated by an LED. A Headphone Jack allows for private listening, with the volume controlled by the main Volume Control. The Mono Button enables monaural reproduction of any input signal, reverting to stereo when released.

For source selection, the amplifier is equipped with Tape Monitor Buttons (TAPE 1 and TAPE 2) for listening to signals from connected tape decks. When these buttons are released, the Function Selector comes into play, allowing users to choose between different program sources: PHONO (for turntables with either MC or MM cartridges), C.D. (for compact disc players), and TUNER (for radio broadcasts). The MM/MC switch, conveniently located on the front panel, allows selection between moving magnet (MM) and moving coil (MC) phono cartridges. It is crucial to set the volume control to zero before switching between MM and MC, or before turning the amplifier on or off, to prevent potential damage or sudden loud noises.

The Volume Control is a dual concentric knob, enabling either separate or combined adjustment of both channels, providing precise control over the listening level. An additional Dubbing Function allows for tape-to-tape copying from TAPE 1 to TAPE 2 by simultaneously depressing both TAPE 1 and TAPE 2 buttons.

On the rear panel, the amplifier provides a comprehensive set of connections. These include input terminals for a Turntable (with separate MC and MM phono inputs), a C.D. Player, a Tuner, and Cassette Decks (TAPE 1 and TAPE 2 with both input and output terminals). There are also Speaker Terminals for connecting right and left speakers, designed for systems with impedance ratings of 4-16 ohms. A grounding wire terminal (GND) is provided for turntable connections to minimize hum.

Usage Features

Before operating the amplifier, it is essential to ensure all connections are properly made and the volume control is set to minimum.

Listening from a Turntable: Set both Tape Monitor buttons to the released (OFF) position. Depress the PHONO button on the function selector, and also the MM/MC button corresponding to your turntable's cartridge type. Start playback on the turntable, then gradually raise the volume.
Listening from a Compact Disc Player or Tuner: Ensure Tape Monitor buttons are in the released (OFF) position. Depress the C.D. button for a compact disc or the TUNER button for radio broadcasts. Begin playback or tune to the desired station, then adjust the volume.
Playing Back a Tape Deck: Depress either the TAPE 1 or TAPE 2 Tape Monitor button, depending on the tape deck in use. Start playback and raise the volume.
Recording Program Source: Play the desired program source as described above. The signal will be sent through the TAPE MONITOR OUT terminals on the rear panel. Put the tape deck into record mode. During recording, the Volume control and Mono button will not affect the signal sent to the TAPE MONITOR OUT terminals.

The amplifier incorporates a Protection Circuit to prevent accidental damage to the unit or speakers. If no sound is produced, a blown fuse might be the cause. In such cases, turn off the unit, disconnect the plug, and consult a dealer or qualified electrician.

Maintenance Features

Proper installation and care are crucial for the longevity and optimal performance of the Rotel RA-840B/RA-840BX.

Power Supply: Always connect the AC line cord to a household wall outlet with a voltage matching the unit's electrical rating, as indicated on the rear panel. Connect or disconnect the AC cord only after turning off the power switch to prevent shock noise or speaker damage.
Ventilation: Ensure the unit is well-ventilated. Never block the ventilation holes on the top and bottom, and provide ample space around the unit. Poor ventilation can lead to excessive heat and potential damage.
Cabinet: Do not open the cabinet to avoid electric shock or damage. If a foreign object enters the unit, turn off the power, disconnect the wall plug, and consult a qualified electrician or dealer.
Installation Location: Place the unit on a level, flat surface, free from humidity, vibration, high temperatures, and direct sunlight. Avoid highly enclosed spaces like near a wall or on a bookshelf, as this can impede ventilation.
Moving the Unit: When transporting, remove the AC cord and all other connected cords from the rear panel to prevent wire breakage and short circuits.
Moisture: If the unit gets wet, immediately disconnect the AC cord and consult a dealer or qualified electrician.
Cleaning: Do not use chemicals such as benzine or thinners on the front panel. Always use a soft, dry cloth to clean the unit.
Owner's Manual: Keep the owner's manual near the unit and record the serial number (found on the rear panel) on the cover for future reference.

Addressing Hum and Noise:

In high-fidelity installations, hum can arise from the interconnection of components, wiring, grounding issues, or component placement. If hum is experienced, disconnect all components except the speakers from the unit. Then, plug in the turntable and, if hum persists, move it away from the speakers. Defective cable connections or cables run too close to strong AC fields can also induce hum. Noise during broadcast reception is often caused by external objects like fluorescent lamps or household appliances. Relocating the unit away from noise sources or using an improved outdoor antenna can help resolve the issue. If the cause cannot be identified, consult a dealer or qualified electrician.

Rotel RA-840B Specifications

General

Total Harmonic Distortion (THD)	0.03%
Input Sensitivity (line)	150 mV
Signal to Noise Ratio (line)	90 dB
Input Sensitivity (MM)	2.5 mV
Signal to Noise Ratio (MM)	75 dB
Output (line)	1 V
Power Output	40W per channel into 8Ω
Frequency Response	10Hz - 100kHz
Dimensions	430 x 330 x 100 mm
Speaker Load Impedance	4Ω - 16Ω