R-A90S R-Series 6/5/4/3 Channel Hi-Res Audio Power Amplifier

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  • Regular price $799.95
Tax included.


  • All-new Advanced Digital Design
  • Compact Chassis
  • Easy Access Controls
  • Low-level RCA Inputs and High-level Speaker Inputs
  • Bandpass Filter
  • Superior Sound Stage
  • Bridgeable
  • Bass EQ
  • High Pass/High Pass High/Low Pass Filters (HPF/HPF-H/LPF)
  • Thermal Protection
  • Rotatable Alpine Badge
  • Remote Bass Knob Ready (RUX-KNOB.2)
  • Hi-Res Audio Certified



  • Output Channels: 6 Channels

RMS Power Ratings

  • Power (@14.4V 1% THD)
    • 75W RMS x 4 +150W RMS x 2 [4Ω@14.4V]
    • 100W RMS x 4 +250W RMS x 2 [2Ω@14.4V]
    • 200W RMS x 2 +500W RMS x 1 [4Ω@14.4V]
  • THD+N (Reference: 10W / rated power into 4 ohms): 0.03% (CH-1/2/3/4)
  • THD+N (Reference: 10W / rated power into 2 ohms): 0.05% (CH-1/2/3/4)
  • THD+N (Reference: 10W / rated power into 4 ohms): 0.03% (CH-5/6)
  • THD+N (Reference: 10W / rated power into 2 ohms): 0.05% (CH-5/6)
  • S/N Ratio: (IHF A Weighted, Reference: rated power into 4 ohms): >103 dB (CH-1/2/3/4)
  • S/N Ratio: (IHF A Weighted, Reference: rated power into 4 ohms): >106 dB (CH-5/6)
  • S/N Ratio: (IHF A Weighted, Reference: 1W into 4 ohms): >85 dB (CH-1/2/3/4)
  • S/N Ratio: (IHF A Weighted, Reference: 1W into 4 ohms): >85 dB (CH-5/6)
  • Damping Factor (Reference: 10W into 4 ohms at 100Hz): >500 (CH-1/2/3/4)
  • Damping Factor (Reference: 10W into 4 ohms at 100Hz): >500 (CH-5/6)

Input Impedance

  • Input Impedance: 10k ohms (CH-1/2/3/4)
  • Input Impedance: 10k ohms (CH-5/6)

Frequency Response 

  • Frequency Response: 10Hz-45kHz (+/-3dB) (CH-1/2/3/4)
  • Frequency Response: 10Hz-45kHz (+/-3dB) (CH-5/6)
  • Frequency Response: 10Hz-45kHz (+/-1dB) (CH-1/2/3/4)
  • Frequency Response: 10Hz-45kHz (+/-1dB) (CH-5/6)


  • Dimensions (WxHxD): 273 x 50.8 x 322mm


  • Weight: 4.52kg

The all-new R-A90S is extreme and class-leading in every way. Beneath its sophisticated and bold design, brings a powerhouse of Alpine ingenuity and technical innovation to create an industry first ‘full-system’ 6-Channel Hi-Res compliant power amplifier.

Delivering serious amounts of power, the R-A90S has the capability to power an entire system with a subwoofer, or can be configured to power an array of 3-way high-end speaker systems with precision using the LP/HP/HP-H/BP crossovers. What’s more, power output is staggered with the capability to deliver different levels of power to each channel regardless of the system configuration.

With performance at the highest standard, the R-A90S has a dynamic range of up to 45kHz and a >500 dampening factor to deliver high power output with precision, as well as a superlative high-definition sound experience.




What is Hi-Res Audio?

You can now appreciate a higher sampling rate than in CD’s for the encoding and playback of music, it brings your favourite tracks to life with extreme clarity. Alpine’s painstaking engineering has delivered faithful audio reproduction from high resolution sound sources and recordings at 96kHz/24Bit or greater, they are optimised for high definition playback and breathtaking performance.

Why Hi-Res Audio?

Listening to Hi Resolution Audio allows you to feel every emotion and hear every nuance; every detail of your favourite artist’s original studio performance is reproduced to perfection. Hi-Res Audio provides absolutely no distortion for the ultimate listening experience.

Versatile System Builds

The R-A90S features a staggered power channel layout that allows each channel to host different levels of power, compared to traditional, multi-channel amplifiers. This allows the R-A90S to effectively function as both a 3-way active amplifier and a 5-channel amplifier by delivering the power you need to the channels where you need it the most.

Now you can use one amplifier to either power an active 3-way sound system or use it to power your speakers and subwoofer without the bulk of an additional amplifier. With ground-breaking multi-functionality and high-power output, Alpine’s all new R-A90S R-Series amplifier enters a new world of Hi-Res sound.

Check out the video at the bottom of the page for more tips on how the R-A90S can take your system to the next level!

All-new Advanced Digital Design

The innovative R-Series amplifier boasts an advanced digital design which unlike a typical Class-D amplifier circuit adds all-digital dual post-filter feedback loop for unmatched accuracy and control, while minimising internal noise.

Extraordinary Damping Factor

The R-A90S R-Series amplifier produces an extraordinary damping factor of >500 for channels 1/2/3/4 and >500 for channels 5/6. This achieves precision control of cone movement at high power outputs with virtually zero distortion.

Hi-Res Audio Compliant

The R-A90S is Hi-Res Audio certified and engineered to operate in an extended frequency range of 10Hz~45kHz. Furthermore, signal-to-noise specifications are at benchmark levels with 103dB for channels 1/2/3/4 and 106dB for 5/6.

Precision Crossovers

The R-A90S is built for system flexibility and precision setup with its extensive crossover capabilities. You can set the HP/LP filters for a full system with a subwoofer, or use the HP-H and bandpass filters for an active 3-Way speaker system.

Benchmark Sound Staging

The R-A90S is optimised for benchmark sound quality, as well as staging and imaging. Rivaling the industry with an incredibly low phase shift of 46° this superior phase curve ensures accurate and defined sound imaging.

Accurate Sound Reproduction

Using the same exclusive technology launched in Alpine’s premium X-Series amplifiers, the R-A90S has dual “Sierra” post-filter feedback loops that correct signal distortion by making the output as close as possible to the original input.


RCA and Speaker Level Inputs

The R-A90S is equipped with low-level RCA inputs, which can also accept high-level speaker signal inputs (via the optional KCE-SP2R). This allows for installation of the amplifier into virtually any aftermarket or OEM factory audio system.

Heavy Duty Gauge Terminals

The speaker and power cable terminals are conveniently located on the 6-channel amplifier providing easy and clean installation. The compact and robust design delivers lossless connectivity.

Control Your Subwoofer

The optional RUX-KNOB.2 remote bass knob controller plugs right into the R-A90S amplifier, providing quick direct subwoofer control to make bass adjustments on the fly enhancing your listening experience. Does your system run two bass knob ready amplifiers? With the use of an additional accessory*, control the bass levels of both of your amplifiers with only one controller.

* Requires a 3rd party RJ45 Splitter

Optimised for Alpine’s R-Series Sound System

Alpine’s stunning R-Series line of speakers, subwoofers, and amplifiers have a heritage of sound quality that can be heard from a block away. The R-A90S 6-channel amplifier is tuned to emphasise the characteristics of the R-Series speakers and subwoofers for a legendary R-Series experience. Visit the systems page to browse our range of systems packs.


For information on installing the R-A90S amplifier in your vehicle, please see the illustrations below.



Front 2-Way + 2 Subwoofers

Front 3-Way + Subwoofer 2 Amplifier System (Connection example with R-A75M)




Front 3-Way System

2 Speakers + Subwoofer (Bridged)

4 Speakers + 2 Subwoofers


4 Speakers + Subwoofer (Bridged)