Riviera R904 Bluetooth marine stereo amplifier is a standalone four-channel audio amplifier for 12 V DC installations. It receives audio wirelessly from compatible smartphones, tablets, and computers, allowing a marine audio system to be set up without a separate stereo or radio unit in the dashboard. An external 2.4 GHz antenna provides a stated Bluetooth range of over 10 meters.
The amplifier delivers 4 × 80 W RMS at 4 Ω or 4 × 120 W RMS at 2 Ω. It can also be bridged to 2 × 230 W RMS at 4 Ω. Power ratings are measured at 14.4 V and 1% THD+N, and the connected speaker load must not be lower than 2 Ω. Up to eight 4 Ω speakers can be distributed across the four channels, and documented setups with four speakers and a subwoofer also exist.
Channel sets A and B each have a choice between high-pass filter, full frequency range, and low-pass filter via an HP/FULL/LP selector. Both high-pass and low-pass filters can be adjusted from 50 to 500 Hz, while the built-in gain control is used to adjust the input sensitivity. The overall frequency range is 10–35,000 Hz, the signal-to-noise ratio is over 90 dB, and the channel separation is over 60 dB.
In addition to Bluetooth, the R904 features an RCA audio input for external audio sources as well as a buffered RCA audio output and remote output for interconnection with additional amplifiers. The permitted input level is 0.2–5 V, and the RCA source must provide at least 200 mV. Intelligent switching between Bluetooth audio and RCA signal as well as automatic reconnection after the initial pairing facilitates daily operation. If a device requires a pairing code, the PIN code 0000 is used.
The electronics are constructed with SMT/SMD components on a double-sided printed circuit board and a MOSFET-based DC-DC PWM converter. Gold-plated terminals provide connection for speakers, +12 V, REM, and ground. Built-in protection circuits include overload, short-circuit, over-temperature, and under-voltage protection. Thermal protection is activated at 80 °C, and separate indicators show power, alarm/protection, and Bluetooth status.
The amplifier must be mounted with four screws on a flat, solid, and ventilated surface in a dry location with low vibration and sufficient heat dissipation. A 4–8 AWG supply cable is recommended depending on cable length, at least 16 AWG speaker wire, and an external 40 A fuse close to the battery's positive terminal. Speaker polarity must be observed, and speaker wires must not be connected directly to chassis ground. Four mounting screws, two plastic end covers, and an external Bluetooth antenna are listed as included.
The manufacturer number for the separate R904 amplifier is 62.00788.00. The model is also included in the complete Riviera Bluetooth Sound System sets 62.00786.00 with two 120 W speakers and 62.00787.00 with two 200 W speakers.
Key featuresFour-channel Bluetooth stereo amplifier for 12 V DC
4 × 80 W RMS at 4 Ω or 4 × 120 W RMS at 2 Ω
Bridgeable to 2 × 230 W RMS at 4 Ω
Minimum speaker load: 2 Ω
RCA input as well as buffered RCA output and remote output
Adjustable high-pass and low-pass filters from 50 to 500 Hz
External 2.4 GHz Bluetooth antenna with range over 10 m
Protection against overload, short-circuit, over-temperature, and under-voltage
Recommended external fuse: 40 A
Four mounting screws and two plastic end covers included
