Power Amplifier 5 W Stereo / 18 W Mono

The RDL RU-PA518 is a compact power amplifier built around two selectable operating configurations. In stereo mode, it delivers more than 5 W RMS per channel into 8 ohms and more than 9 W RMS per channel into 4 ohms. In bridged mono mode, it delivers more than 18 W RMS into 8 ohms. Two line-level inputs, balanced and unbalanced connection options, front-panel control, a selectable built-in peak limiter, and a one-third-rack chassis define its core feature set.

Ideal Use Cases

The RU-PA518 is best matched to installations whose speaker load and power requirement fall within its published output ratings. Stereo mode serves two-channel systems with 8-ohm or 4-ohm loads, while bridged mono mode addresses a single 8-ohm load. Its selectable configuration allows the same amplifier model to support either of these defined system layouts.

• Two-channel amplification requiring more than 5 W RMS per channel into 8 ohms.
• Two-channel amplification requiring more than 9 W RMS per channel into 4 ohms.
• Bridged-mono operation requiring more than 18 W RMS into an 8-ohm load.
• High-density equipment layouts that benefit from a one-third-rack form factor.

Why Choose This Model

The amplifier accommodates two line-level inputs with support for +4 dBu nominal balanced signals and -10 dBV nominal unbalanced signals. Balanced connections are provided on a barrier block, while unbalanced connections use phono jacks. Input impedance is 20 kilohms balanced bridging or 10 kilohms unbalanced. This gives installers clearly specified interfaces for integrating the amplifier with different line-level sources.

Front-panel control is provided for the two inputs. The built-in peak limiter is selectable, allowing it to be engaged according to the requirements of the installation. Stereo or bridged-mono operation is also selectable, placing the amplifier’s principal configuration choices within one compact model.

Installation and Integration

The RU-PA518 measures 1.7 inches high, 5.8 inches wide, and 8.0 inches deep, equivalent to 4.3 by 15.0 by 20.3 centimeters. Its one-third-rack format supports high-density rack mounting. Balanced barrier-block and unbalanced phono-jack inputs provide two documented connection methods without requiring assumptions about the source interface.

Power is ground-referenced 24 Vdc. Current requirement is 1500 mA at RMS output or 1000 mA with continuous music or voice. The recommended power supplies are the PS-24V3A for the USA and PS-24V3 for international use; the power supply is not included. The specified ambient operating range is 0 to 40 degrees C, with 20 degrees C recommended. Minimum input levels for rated power are -6 dBu balanced and -20 dBV unbalanced. Maximum input levels are +20 dBu balanced and +6 dBV unbalanced.

Performance Highlights

Frequency response varies with operating mode and load. In stereo mode with an 8-ohm output at 5 W RMS, response is 20 Hz to 40 kHz at ±1 dB. In stereo mode with a 4-ohm output at 9 W RMS, response is 25 Hz to 40 kHz at ±1 dB. In bridged-mono mode with an 8-ohm output at 18 W RMS, response is 25 Hz to 30 kHz at ±1 dB.

THD+N is specified at less than 0.05% below rated power at 1 kHz and less than 0.1% below 18 W RMS from 50 Hz to 20 kHz. Noise is specified at less than -85 dB below rated output. CMRR is greater than 55 dB from 50 Hz to 120 Hz, while stereo-mode crosstalk is less than -60 dB at 1 kHz. These published measurements make it possible to evaluate the amplifier against defined signal, load, and bandwidth requirements.

What Makes It Different

The RU-PA518 combines two output arrangements with load-specific power ratings in a single one-third-rack chassis. Its stereo capability is not limited to the 5 W rating at 8 ohms; the published output increases to more than 9 W RMS per channel with 4-ohm loads. Bridging the amplifier provides more than 18 W RMS into 8 ohms for systems requiring a single mono output.

The combination of balanced and unbalanced inputs, front-panel input control, selectable peak limiting, and selectable stereo or mono operation distinguishes the model’s integration options. Each operating mode is supported by its own published output and frequency-response information.

Final Assessment

The RDL RU-PA518 is a focused choice for systems that match its defined stereo or bridged-mono ratings. It offers two line inputs, balanced and unbalanced connectivity, front-panel control, selectable limiting, and compact rack integration. Before installation, confirm the required speaker impedance, input signal standard, operating mode, and 24 Vdc power arrangement. Because the recommended power supply is not included, it should be selected separately for the intended region.