Rebec RS4.1D – 4.1-Channel Class D DSP Amplifier with Dedicated Subwoofer Power

Product Overview

The Rebec RS4.1D is a DSP amplifier from Rebec’s RS Series, combining four full-range amplifier channels with one dedicated high-power channel in a single Class D platform.

Its 4.1-channel architecture is the defining characteristic of the RS4.1D. At 4Ω, the four main channels provide 100W RMS each, while the fifth channel delivers 250W RMS. The dedicated channel can operate at lower impedances, increasing to 400W RMS at 2Ω and 600W RMS at 1Ω.

This allows the RS4.1D to handle both the main loudspeakers and a subwoofer from one integrated DSP amplifier, while eight low-level DSP outputs provide additional flexibility for system expansion.

4 + 1 Class D Amplifier Architecture

Unlike a conventional four- or multi-channel DSP amplifier with identical channels throughout, the Rebec RS4.1D divides its amplification into two distinct sections.

At 14.4V and 4Ω, rated output is:

100W RMS × 4CH + 250W RMS × 1CH, at 0.1% THD.

The first four channels are intended for the main loudspeaker system, while the fifth channel provides substantially higher output for a more power-demanding section of the system.

This architecture allows multiple speaker sections to be managed without requiring a separate mono amplifier simply to obtain a higher-power channel.

Dedicated High-Power Channel with 1Ω Capability

The fifth channel is one of the most important characteristics of the RS4.1D.

Its rated output increases according to load impedance:

250W RMS ×1 @4Ω
333W RMS ×1 @3Ω
400W RMS ×1 @2Ω
600W RMS ×1 @1Ω

All of these RMS ratings are specified at 14.4V and 0.1% THD.

The ability to operate the dedicated channel down to 1Ω makes it particularly relevant for subwoofer amplification, while the four main channels continue to power the rest of the speaker system.

In practical system design, this means DSP processing, four-channel speaker amplification and dedicated subwoofer amplification can all be integrated into the same unit.

Strong Four-Channel Main Amplification

The Rebec RS4.1D is not built around the subwoofer channel alone.

Its four main amplifier channels provide 100W RMS ×4 at 4Ω, increasing to 133W RMS ×4 at 3Ω and 150W RMS ×4 at 2Ω, all specified at 0.1% THD.

This gives the main channels considerably more output capability than the lower-powered integrated channels found in many compact DSP amplifier architectures.

Depending on the system configuration, these four channels can be assigned to different front or rear speaker sections while the fifth channel independently handles the subwoofer.

Bridge Capability for Channels 1–4

The first four amplifier channels can also be configured in bridged pairs.

CH1+CH2 and CH3+CH4 can provide:

300W RMS ×2 at 4Ω, measured at 0.1% THD.

Maximum bridged output is specified at 600W ×2 at 4Ω, measured at 10% THD.

This provides an alternative way of using the four main amplifier channels when a system requires fewer channels but greater output per channel.

The dedicated fifth channel remains separate from this bridge configuration.

8-Channel DSP Output for System Expansion

Although the RS4.1D contains five amplified channels, it provides eight low-level outputs at 2.35V.

This gives the DSP platform greater channel flexibility than the built-in 4.1-channel amplifier architecture alone.

External amplifiers can be connected to these processed outputs when additional speaker channels or a different amplification arrangement is required.

The RS4.1D can therefore function as an integrated 4.1-channel solution or become the processing center of a larger audio system.

AP5868 DSP Processing

The Rebec RS4.1D uses the AP5868 DSP chipset, combined with a CJC4344 DAC and ES7210 ADC.

DSP processing operates at a 48kHz sampling frequency, with a specified dynamic range of 93dB and signal-to-noise ratio of 105dB.

For acoustic adjustment, the processor provides 31-band EQ.

Its crossover section supports Butterworth, Linkwitz and Bessel filter types, providing different filter characteristics for configuring individual loudspeaker operating ranges.

The system also provides six presets for saving and recalling tuning configurations.

Unlike several RPX-B models that specify PC-only tuning, the RS4.1D supports tuning through PC or App.

Analog and Factory-System Integration

The RS4.1D provides four high-level inputs supporting 7.9–24.9Vpp, allowing integration with compatible factory speaker-level sources.

It also provides four low-level inputs supporting 1.3–5.1Vpp.

This gives the unit both speaker-level and line-level analog integration options, depending on the source system used in the vehicle.

192kHz/24-Bit Digital Inputs

Digital connectivity includes both Optical (Toslink) and Coaxial inputs supporting up to 192kHz/24-bit.

The Rebec RS4.1D also provides a dedicated USB Audio input.

For wireless audio, built-in Bluetooth 5.4 provides another source option.

The RS4.1D can therefore receive audio from factory high-level sources, analog low-level sources or several forms of digital input within the same DSP platform.

Signal Performance and Integrated Design

The Rebec RS4.1D has a specified frequency response of 20Hz–20kHz.

Signal-to-noise ratio is rated at 105dB, while total harmonic distortion is specified at below 0.01% for low-level signals and below 0.03% for high-level signals.

The unit operates from a 10–16V automotive electrical supply and has a specified maximum current of 170A.

Its chassis measures approximately 221 × 208 × 50 mm.

Within this enclosure, Rebec integrates DSP processing, four main amplifier channels, a dedicated high-power channel and multi-channel processed output.

One DSP Amplifier for Main Speakers and Subwoofer

The main advantage of the Rebec RS4.1D lies in how its amplifier channels are structured.

Instead of simply providing five identical channels, it combines four 100W RMS channels with one substantially more powerful channel capable of up to 600W RMS at 1Ω.

This allows the four main channels and the subwoofer channel to perform clearly differentiated roles within the same amplifier.

The ability to bridge channels 1–4 into 300W RMS ×2 at 4Ω adds another configuration option, while the eight low-level DSP outputs allow external amplification to be incorporated when the system needs to expand.

Combined with AP5868 DSP processing, 31-band EQ, Butterworth/Linkwitz/Bessel crossover options, six presets, PC/App tuning, 192kHz/24-bit Optical and Coaxial inputs, USB Audio and Bluetooth 5.4, the RS4.1D provides a versatile integrated platform for car audio systems requiring both multi-channel speaker amplification and dedicated subwoofer power.

Rebec RS4.1D

4.1-Channel Class D DSP Amplification with Dedicated High-Power Output for Integrated Speaker and Subwoofer Systems.