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Instructions for safe power supply connection, unit placement, and ventilation.
Guidance on connecting speaker systems with appropriate impedance ratings.
Detailed steps for connecting speaker leads to the amplifier terminals.
Explanation of the phono cartridge load selector for optimizing performance.
Description of PRE OUT and MAIN IN terminals for pre-amplifier or power amplifier use.
Function of the power button and description of Power/Bridged Mono Indicators.
Usage of the headphone jack for private listening.
Function and meaning of the protection circuit indicator.
How to use the volume control and select audio reproduction modes.
Selecting signals for listening or tape copying.
Steps for listening to turntables, CD players, or tuners.
Instructions for playing back and recording from tape decks.
Procedure for copying tapes from one deck to another.
The Rotel RA-870 is a stereo integrated amplifier designed for high-fidelity audio reproduction. It combines a preamplifier and a power amplifier in a single unit, offering a comprehensive solution for driving speaker systems and managing various audio sources. The amplifier is engineered with a focus on sound quality and user-friendly operation, incorporating Rotel's long experience in audio equipment manufacturing.
The primary function of the RA-870 is to amplify audio signals from various sources and deliver them to speakers. It features multiple input terminals on its rear panel, including PHONO (MM/MC), CD, TUNER, TAPE 1, and TAPE 2, allowing connection of a wide range of audio components such as turntables, CD players, tuners, and cassette decks.
The amplifier includes a built-in phono stage with selectable Moving Magnet (MM) and Moving Coil (MC) cartridge compatibility. This allows users to connect different types of turntables directly to the amplifier without the need for an external phono preamplifier. A phono cartridge load selector is also provided, offering three capacitance settings (100pF, 200pF, and 300pF) to optimize performance for various cartridges.
For output, the RA-870 provides speaker terminals for connecting a pair of stereo speakers. It also features a headphone jack on the front panel for private listening, which mutes the speakers when headphones are plugged in. The volume of the headphone output is controlled by the main volume knob.
Beyond its integrated amplifier function, the RA-870 offers flexibility through its PRE OUT and MAIN IN terminals. The PRE OUT terminals supply a signal from the preamplifier section, allowing the unit to be used as a standalone stereo preamplifier when connected to a separate power amplifier. Conversely, the MAIN IN terminals provide input to the unit's main amplifier section, enabling the RA-870 to function as a stereo power amplifier when connected to a separate preamplifier. This modular design allows for system expansion and customization.
A unique feature is the ability to combine the RA-870 with a Rotel RB-870 stereo power amplifier in a bridged connection (BTL). In this configuration, the main amplifier section of the RA-870 can be utilized as a monaural power amplifier to drive one channel, while the RB-870 drives the other channel in bridged mode, significantly increasing the power output capability for each channel. A NORMAL-BRIDGED/SEPARATE selector on the rear panel manages these configurations.
The amplifier incorporates a protection circuit designed to prevent damage from abnormal conditions such as excessively high temperatures or short circuits. If activated, the protection indicator on the front panel will light up, and sound output will be temporarily cut off. This circuit also prevents popping noises when the unit is turned on or when switching the Phono MM/MC selector.
The RA-870 is designed for straightforward operation. The front panel features a power button, a volume control, a mode selector (STEREO, MONO, REVERSE), a tape monitor selector, and function selector buttons (PHONO, CD, TUNER, TAPE 1, TAPE 2).
The volume control is a dual-concentric knob, allowing for either separate or combined adjustment of both channels. The mode selector allows users to choose between normal stereo reproduction, monophonic reproduction, or reverse channel reproduction. The tape monitor selector enables listening to signals from connected tape decks and facilitates tape-to-tape copying between two decks.
The function selector buttons allow users to easily switch between different input sources. When the tape monitor selector is set to SOURCE, these buttons become active for selecting the desired audio input.
For recording, the RA-870 sends the selected program source signal through its TAPE MONITOR OUT terminals on the rear panel. During recording, the volume control and mode selector do not affect the signal being sent to the recording device, ensuring a clean signal path.
The rear panel also includes two switched AC outlets, each rated at 100 watts maximum. These outlets provide power to other audio equipment (turntable, CD player, tuner, cassette deck) that are used in conjunction with the RA-870, turning them on or off with the amplifier's main power switch. Users are cautioned not to connect equipment exceeding the rated power consumption or other power amplifiers to these outlets.
The RA-870 requires minimal maintenance. For cleaning the front panel, users are advised to use a soft, dry cloth and avoid chemicals such as benzine or thinners.
Proper ventilation is crucial for the unit's longevity and performance. Users should ensure that ventilation holes on the top and bottom of the unit are not blocked and that ample space is provided around the unit to prevent excessive heat buildup, which could activate the protection circuit. The amplifier should be placed on a level and flat surface, away from humidity, vibration, high temperatures, and direct sunlight.
In case of a foreign object falling inside the unit or if the unit gets wet, users are instructed to immediately turn off the power, disconnect the AC cord, and consult a qualified electrician or dealer. The cabinet should never be opened by the user to avoid electric shock or damage to components.
For troubleshooting hum and noise, the manual suggests checking cable connections, ensuring proper grounding, and relocating the turntable or the unit away from speakers or strong AC fields. For broadcast noise, relocating the unit or using an improved outdoor antenna is recommended.
The manual also provides guidance for addressing protection circuit activation. Users should first turn off the power, disconnect the plug, and check for short-circuited speaker cables or speakers with impedance below 8 ohms. After checking these points, turning the power back on should deactivate the protection circuit and restore normal operation. If the issue persists, users are advised to consult a dealer or qualified electrician.
The RA-870 is designed for variable voltage operation (120V, 220V, or 240V), though this feature is not available for all regions. Users moving to an area with a different power supply voltage should consult their dealer. The serial number, located on the rear panel, should be recorded on the manual's cover for reference.
Power Output| continuous power output | 60 watts per channel |
|---|---|
| DIN output | 118 watts per channel |
| power output (BTL) | 120 watts (mono) |
| total harmonic distortion | 0.03% |
Impedance| output speaker impedance | 8-16 ohms |
|---|---|
| headphone impedance | 4-16 ohms |
| phono (MC) input sensitivity/impedance | 0.2 mV/200 ohms |
| phono (MM) input sensitivity/impedance | 2.5 mV/47 kohms |
Power Requirements| power requirement | 120V/60 Hz. 220V/50 Hz, 240V/50 Hz |
|---|---|
| power consumption | 500 watts |
Weight and Dimensions| dimensions | 430 (W) x 91 (H) x 317 (D) mm |
|---|---|
| weight | 9.8 kg/21.56 lbs |
