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 Stage 4 amplifier and speaker system ensures your music sounds incredible, even at 100 mph.
Why Choose the Volunteer Audio Stage 4 System?
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Exceptional Sound Clarity: Our package delivers powerful, clear audio, allowing you to enjoy your favorite tunes without distortion, no matter how fast you’re going.
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Easy Upgrade: Keep your factory radio while enhancing your sound system. Our prewired amplifier is set up for optimal performance with your factory Skyline OS Infotainment radio.
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Durability: The IP64 rated compact amplifier is moisture-resistant, and the Hertz speakers feature weather-resistant cones, making them perfect for any riding conditions.
What’s Included in the Stage 4 Package?
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Prewired Amplifier: Gains and filters adjusted specifically for your factory Skyline OS Infotainment radio.
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1 Pair of Hertz SX165NEO 6.5” Upper Fairing Speakers: High-quality replacements for your factory speakers.
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1 Pair of Hertz SV165NEO 6.5” Tour Pak Speakers: Designed for clear sound and durability.
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Hertz Power/Ground Harness: Ensures reliable power and grounding for optimal performance and longevity.
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Volunteer Audio HD-A2B8 Interface: Seamlessly integrates with your Harley Davidson, expertly tuned for Hertz systems.
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BC-SPG Tour Pak Grilles: Stylish and functional grilles to protect your new speakers and complete your audio upgrade with a sleek look.
Why Volunteer Audio?
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Pre-Configured Convenience: We do all the hard work for you. Your kit arrives with gains and filters already set, making installation straightforward.
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Step-by-Step Support: Our detailed videos guide you through the installation process, and our lifetime tech support is always here to help.
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Lifetime Tech Support: We offer lifetime support for any items purchased from us, ensuring you have assistance whenever needed.
American Hard Bag Modular Bass System
The American Hard Bag Modular Bass System is available with your choice of two premium 10-inch subwoofers.
Both have been extensively tested in this enclosure and both deliver exceptional performance. Neither is better. They simply have different personalities.
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
Hertz Reference Edition
Legendary Hertz Performance
The Hertz CS 250 S2 has earned a reputation for delivering exceptionally deep, controlled bass from compact enclosures, making it an ideal match for the American Hard Bag Modular Bass System.
Rated at 300 Watts RMS and 600 Watts Maximum Power, the CS 250 S2 utilizes a high-density ferrite motor, polypropylene cone, and precision-engineered suspension to reproduce the lowest octaves with outstanding authority and control.
If your music library includes hip-hop, rap, EDM, pop, or other bass-heavy genres, the Hertz Edition delivers the effortless low-frequency extension that brings those tracks to life.
Ideal For: Hip-Hop, Rap, EDM, Pop, R&B, and Bass-heavy playlists
Performance Highlights:
- 300 Watts RMS
- 600 Watts Maximum Power
- 2 Ohm Voice Coil
- Polypropylene Cone
- High-Density Ferrite Magnet
- 35 mm Voice Coil
Expect:
- Exceptional low-frequency extension
- Smooth, effortless bass reproduction
- Powerful sub-bass authority
- Outstanding musical accuracy
Volunteer Audio Recommendation
At Volunteer Audio, we’ve spent countless hours listening to, tuning, and testing both versions of this system.
Rather than offering a one-size-fits-all solution, we chose to offer two distinct subwoofer options because each excels with different styles of music.
If your playlist is primarily country, rock, blues, or live recordings, we generally recommend the Velocity Performance Edition. It delivers exceptional punch, outstanding musicality, and was engineered specifically for the American Hard Bag enclosure.
If your music leans toward hip-hop, rap, EDM, or you simply want to reproduce the deepest notes possible, we recommend the Hertz Reference Edition for its exceptional low-frequency extension.
There isn’t a better version.
There’s simply the version that’s better suited to the music you enjoy most.
If you’re unsure which system is right for you, give our team a call. We’ll be happy to help you choose the perfect setup for your motorcycle and your listening preferences.
Complete Kit Includes
- Left American Hard Bag modular enclosure
- Right American Hard Bag modular enclosure
- Two 10-inch subwoofers (Velocity or Hertz, depending on the model selected)
- Two integrated 8-inch passive radiators
- Plug-and-play amplifier-to-saddlebag wiring harness
- Saddlebag vent assemblies
- Precision vent cutting template
- Saddlebag vent installation hardware
- Complete mounting hardware
- All required installation components
Compatible With:
2023.5 and newer Harley-Davidson Touring motorcycles equipped with the redesigned saddlebags
Volunteer Audio Hertz A2B Stage 2 Systems
Volunteer Audio Hertz A2B Stage 4 Systems
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:
• Includes preloaded DSP tunes for:
• Hertz Audio Systems
• Velocity Audio Systems
• Extreme Audio Systems
• …and many more manufacturers coming soon!
• Easily pair with any universal amplifier for fast, optimized installation.
Hertz SP4.900 Amplifier
Our friends at Hertz have released a game changer for motorcycle audio! The Hertz SP4.900 amplifier offers a small footprint but huge output. It’s the most powerful amp available in its size, delivering 160W RMS @ 4Ω and 250W RMS @ 2Ω. With a remarkably low distortion rate of 0.02% THD, it’s the perfect choice for your motorcycle audio system.
Technical Specs:
Output Nominal Power (RMS) @ 14.4 VDC, THD 1%:
4 Ch:
160 W x 4 (4Ω)
250 W x 4 (2Ω)
3 Ch:
160 W x 2 (4Ω) + 500 W x 1 (4Ω)
250 W x 2 (2Ω) + 500 W x 1 (4Ω)
2 Ch:
500 W x 2 (4Ω)
Total Power RMS: 1000 W
Dyno Specs:
Box rating: 160 watts at 4Ω, Dyno reads 173 watts at 4Ω
Box rating: 250 watts at 2Ω, Dyno reads 288 watts at 2Ω
Ready to Elevate Your Ride?
At Volunteer Audio, we’re committed to providing you with an amazing sound system for your Harley Davidson. Our Stage 4 package is designed for top-notch performance and durability, transforming your motorcycle into a high-quality audio experience. Ready for a sound transformation? Let us help you get there!
