Velocity Stage 4 Ultimate A2B Plug & Play Amp And Speaker Package with Modular Subwoofer Kit For 2026 Harley Davidson® Road Glide Limited Motorcycles

Tired of struggling to hear your factory Harley speakers at highway speeds? Or constantly replacing blown speakers? You’re not alone!

At Volunteer Audio, we understand these common frustrations, and we’ve created a solution that will revolutionize your riding experience. Our Velocity Razor Stage 4 amplifier, speaker, and subwoofer system delivers the clarity, output, midbass, and low-frequency performance needed to keep your music sounding incredible even at highway speeds.

Why Choose the Volunteer Audio Stage 4 System?

• Exceptional Sound Clarity: Our Velocity Razor package delivers powerful, clear audio with excellent vocal detail, crisp highs, and strong midbass, allowing you to enjoy your favorite music without distortion even at highway speeds.
• Easy Upgrade: Keep your factory radio while enhancing your sound system. Our prewired Velocity Razor Pro amplifier is set up for optimal performance with your factory Skyline OS Infotainment radio.
• True Low-Frequency Performance: The American Hard Bag IP24SWEV Modular Subwoofer Kit adds the deep, musical bass and low-frequency impact that your full-range motorcycle speakers simply can't reproduce on their own.
• Durability: The Velocity Razor Pro amplifier and Velocity Razor Coax Neo speakers are designed for demanding motorcycle audio applications, providing reliable, high-output performance in real-world riding conditions.

What’s Included in the Stage 4 Package?

• Prewired Velocity Razor Pro RZP2000.6 Amplifier: Gains and filters are professionally adjusted specifically for your factory Skyline OS Infotainment radio.
• 1 Pair of Velocity Razor Coax Neo RCN65 6.5” Upper Fairing Speakers: High-output neodymium coaxial speakers designed to deliver crystal-clear vocals, detailed highs, and powerful midbass at highway speeds.
• 1 Pair of Velocity Razor Coax Neo RCN65 6.5” Tour Pack Speakers: Matching high-output neodymium coaxial speakers that provide excellent rear fill and balanced sound for both rider and passenger.
• American Hard Bag IP24SWEV Modular Subwoofer Kit: Complete modular bass system featuring the Velocity Performance Edition 10-inch subwoofer, engineered specifically for the American Hard Bag enclosure to deliver tight, musical bass with outstanding impact and low-frequency performance.
• Velocity Razor Power/Ground Harness: Ensures clean, reliable power and grounding for optimal amplifier performance and longevity.
• Volunteer Audio HD-A2B8 Interface: Seamlessly integrates with your Harley-Davidson®, expertly tuned for Velocity Razor systems.
  

Why Volunteer Audio?

• Pre-Configured Convenience: We do all the hard work for you. Your kit arrives with gains and filters already set, making installation straightforward.
• Step-by-Step Support: Our detailed videos guide you through the installation process, making your upgrade as straightforward as possible.
• Lifetime Tech Support: We offer lifetime support for any items purchased from us, ensuring you have assistance whenever needed.

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American Hard Bag Modular Bass System

Velocity Performance Edition

Engineered Specifically for the American Hard Bag Enclosure

The Velocity 10-inch subwoofer wasn’t selected from an existing catalog.

It was engineered specifically for the American Hard Bag enclosure, creating a system where the driver, enclosure, and passive radiator were developed together as a complete acoustic package.

Rated at 300 Watts RMS and 600 Watts Maximum Power, the Velocity subwoofer features an injection-molded cone, Santoprene surround, oversized 56-ounce ferrite motor, and a 38 mm TIL voice coil to deliver exceptional punch, musicality, and long-term reliability.

If your playlist is filled with country, rock, blues, classic rock, or live recordings, the Velocity Performance Edition delivers outstanding impact and natural musical accuracy.

Ideal For: Country, Rock, Classic Rock, Southern Rock, Blues, and Live Recordings

Performance Highlights:

• 300 Watts RMS

• 600 Watts Maximum Power

• Frequency Response: 20–400 Hz

• Injection-Molded Cone

• Santoprene Surround

• 38 mm TIL Voice Coil

• 56 oz Ferrite Magnet

Expect:

• Tight, punchy bass

• Incredible kick drum impact

• Excellent bass guitar definition

• Fast transient response

• Natural, musical low frequencies

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HD-A2B8 Amplifier Replacement Interface

Compatibility:

• Designed for Harley-Davidson models equipped with the Skyline OS Infotainment Unit.

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Purpose:

• Allows for the removal of the stock amplifier.

• Facilitates the installation of higher power aftermarket amplifiers.

• Maintains compatibility with factory-installed Rockford Fosgate subwoofers and rear-mounted secondary amplifiers.

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Manufacturer:

• Designed and manufactured by SeirenHD exclusively for Volunteer Audio.

• Engineered and manufactured in the USA.

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Pre-Tuned for Plug-and-Play Performance

The HD-A2B8 interface from Volunteer Audio and SeirenHD is ready to install right out of the box—no tuning required for standard systems.

Already optimized for immediate use:

• Flat EQ Curve – Delivers a clean, uncolored audio signal

• Pre-Set Output Levels – Optimized to run clean at full volume with zero clipping

• Speed-Controlled Volume – Fully retained and pre-configured to match factory behavior

• Fader Support – Works immediately without any setup

• All Factory Features Intact – Including navigation prompts, radio EQ selections, and more

Tuning is optional, only necessary when:

• Activating crossovers

• Using the 31-band or 10-band EQ to customize for specific speaker setups

• Adjusting time alignment or per-channel output levels

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Plug-and-Play Harnessing

The HD-A2B8 includes a harness that connects directly to all factory speaker wiring with zero modification to your motorcycle.

For expanded setups, additional plug-and-play harnessing is available below:

• Underseat Harness – Pins into the factory plug on base model bikes

• Lid Disconnect Harness – Clean, quick-disconnect solution for 6x9 lid speaker installations

• Tour Pack Harness – Adds plug-and-play rear audio for Tour Pack installations

• Lower Fairing Harness – Simple solution for adding speaker pods to your lower fairings

All harnessing options are pre-configured and labeled for quick installation and available for purchase below.

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Integration Features:

• Utilizes the OE A2B chip for seamless factory integration

• Supports all factory infotainment updates

• Retains full factory functionality, including:

 • Fader

 • EQ selections with DSP profile adjustments

 • Speed-controlled volume

 • Navigation prompts

 • Digital A2B subwoofer output for HD Audio by Rockford systems

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DSP Specifications:

• 10 Output Channels with Full DSP Control:

 • 8 Analog RCA Outputs

 • 2 Digital A2B Outputs (for Rockford subwoofers)

• Equalization:

 • Per-channel 31-band graphic EQ or 10-band parametric EQ

 • Global 7-band parametric EQ mirrors infotainment custom EQ settings

• Time Alignment:

 • Independent delay settings for every channel

• Crossover Control:

 • Independent high-pass and low-pass filters per output pair

• Level Adjustment:

 • Individual channel-level control for precise tuning

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Technical Specifications:

• RCA Outputs:

 • 8 Channels, 4v RMS

 • Front, Rear, Subwoofer, and Auxiliary output configuration

• Frequency Response: 20 Hz – 24 kHz

• Signal-to-Noise Ratio: 112 dB

• DSP Resolution: 32-bit

• Operating Voltage: 6–28 volts

• Current Draw:

 • Idle: 14 µA

 • Full Power: 300 mA

• Warranty: 1 Year

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DSP Tuning Access:

• All DSP settings and tuning are available through the SeirenHD DSP tuning interface.

• Includes preloaded DSP tunes for:

 • Hertz Audio Systems

 • Velocity Audio Systems

 • Extreme Audio Systems

 • …and many more manufacturers coming soon!

• Easily pairs with universal amplifiers for fast, optimized installation.

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Ready to Elevate Your Ride?

At Volunteer Audio, we’ve combined the Velocity Razor Pro amplifier, Velocity Razor Coax Neo RCN65 speakers, and the American Hard Bag IP24SWEV Modular Subwoofer Kit to create a Stage 4 system that delivers far more than just additional volume.

You get crystal-clear sound from the upper fairing, excellent rear fill from the Tour Pack, strong midbass, and tight, musical low-frequency impact from the Velocity Performance Edition 10-inch subwoofer.

The result is a complete motorcycle audio experience with the clarity, output, and bass needed to enjoy your music the way it was meant to be heard.

Ready for a sound transformation? Let Volunteer Audio help you take your Harley audio to the next level.