Nissan Murano Spare Tire Subwoofer

The Nissan Murano, a stylish crossover known for its comfortable ride and distinctive design, often hides a secret weapon in its spare tire well: a factory-installed subwoofer. This isn't your average, bolted-on aftermarket bass booster. Instead, Nissan engineers cleverly integrated a dedicated subwoofer system into the vehicle's existing architecture, maximizing space and delivering a more refined audio experience. This guide dives deep into the design, function, and technical intricacies of the Murano's spare tire subwoofer system.

The Philosophy Behind the Design

Why the spare tire well? Space is at a premium in any vehicle. Placing a large, conventional subwoofer enclosure would consume valuable cargo area. By utilizing the spare tire well, Nissan minimized the system's intrusion into the vehicle's usable space. This clever design also provides a relatively enclosed volume, which is beneficial for low-frequency sound reproduction. The goal was to provide a decent amount of bass without sacrificing too much of the utility and function of the vehicle. Let’s explore some of the reasons why you might find this type of design preferable:

Space Saving: Preserves cargo area by utilizing otherwise unused space.

Stealth Integration: Keeps the subwoofer hidden from view, maintaining the vehicle's aesthetics.

Acoustic Benefit: The spare tire well acts as a partial enclosure, improving bass response.

Component Breakdown

Let's dissect the key components of the Murano's spare tire subwoofer system:

1. The Subwoofer Driver

The heart of the system is the subwoofer driver itself. Typically, this is a relatively small (8-10 inch) driver designed for free-air or infinite baffle applications. Free-air drivers are specifically designed to operate without a dedicated enclosure. In the Murano, the spare tire well serves as a partial enclosure, but the driver's design still leans heavily towards free-air principles. Key characteristics include:

High Excursion: The driver needs to move a significant amount of air to produce low frequencies. Look for designs with high Xmax (maximum linear excursion).

Low Resonance Frequency (Fs): A low Fs allows the driver to reproduce very low frequencies effectively.

Durable Cone Material: Commonly polypropylene or treated paper, chosen for stiffness and resistance to moisture.

The driver's impedance (typically 2 or 4 ohms) is crucial for matching it with the amplifier's output. Mismatched impedance can lead to poor performance or damage to the amplifier.

2. The Enclosure (Spare Tire Well)

While not a traditional enclosure, the spare tire well plays a critical role in shaping the subwoofer's sound. The volume of the well, its shape, and any dampening materials present all affect the subwoofer's frequency response and overall output. The well itself is usually made of metal which is good at conducting sound. Therefore, one might line the well with damping material. Some of the methods of doing this are:

Dynamat: A common automotive sound dampening product.

Foam Padding: Helps absorb vibrations and reduce resonances.

Fiberglass: Applied to the walls of the well for vibration dampening.

The lack of a completely sealed enclosure means the subwoofer operates in a pseudo-infinite baffle configuration. This tends to produce a flatter frequency response but can result in lower overall output compared to a sealed or ported enclosure of comparable size. The frequency response, however, is heavily dependent on the volume and depth of the spare tire wheel.

3. The Amplifier

A dedicated amplifier powers the subwoofer. This amplifier is typically located near the spare tire well or integrated into the car's head unit/audio system. The amplifier's power output must be matched to the subwoofer's power handling capabilities. Overpowering the subwoofer can lead to damage, while underpowering it will result in weak bass. The amplifier's specifications are critically important. Some things to consider are:

RMS Power: The continuous power the amplifier can deliver. This should be close to the subwoofer's RMS power handling.

Impedance Matching: The amplifier must be able to handle the subwoofer's impedance (e.g., 2 or 4 ohms).

Crossover: A built-in crossover allows the amplifier to filter out high frequencies, ensuring only low frequencies are sent to the subwoofer.

Gain Control: Allows adjusting the amplifier's input sensitivity to match the head unit's output level.

4. Wiring and Signal Source

The subwoofer system requires power, ground, and a signal source. The power cable typically runs directly from the vehicle's battery, often with a fuse for protection. The ground wire is connected to the vehicle's chassis. The signal source can come from one of several places:

Low-Level (RCA) Outputs: If the head unit has dedicated subwoofer outputs, these provide the cleanest signal.

High-Level (Speaker) Inputs: Some amplifiers can accept speaker-level inputs, tapping into the existing rear speaker wires.

The choice of signal source can affect the subwoofer's sound quality. Low-level inputs generally provide a cleaner signal, while high-level inputs may introduce noise or distortion.

How It Works: The Audio Chain

Let's trace the audio signal's path through the subwoofer system:

The head unit (or infotainment system) generates the audio signal.
The head unit sends the subwoofer signal (either through low-level or high-level outputs) to the amplifier.
The amplifier amplifies the signal and applies a crossover to filter out high frequencies.
The amplified low-frequency signal is sent to the subwoofer driver.
The subwoofer driver vibrates, creating sound waves.
The spare tire well acts as a partial enclosure, shaping the subwoofer's frequency response.
The sound waves radiate into the vehicle's cabin, adding bass to the overall audio experience.

Advantages and Disadvantages

The Murano's spare tire subwoofer system offers several advantages:

Space Efficiency: Maximizes cargo space by utilizing the spare tire well.

Integrated Design: Blends seamlessly into the vehicle's interior.

Improved Bass Response: Enhances the overall audio experience with deeper bass.

However, there are also some drawbacks:

Limited Output: Free-air designs typically don't produce as much bass as enclosed subwoofers.

Potential for Rattles: The spare tire well can be prone to rattles if not properly dampened.

Reduced Spare Tire Access: Accessing the spare tire may require removing the subwoofer.

Modifications and Upgrades

While the factory subwoofer system provides a decent bass response, it can be further improved through modifications and upgrades. Here are some common modifications:

1. Subwoofer Replacement

Replacing the factory subwoofer driver with a higher-quality aftermarket driver can significantly improve bass performance. Look for a driver specifically designed for free-air or infinite baffle applications and with power handling capabilities that match your amplifier.

2. Amplifier Upgrade

Upgrading to a more powerful amplifier can provide cleaner, more dynamic bass. Be sure to match the amplifier's impedance and power output to the subwoofer's specifications.

3. Enclosure Modification

Adding dampening material to the spare tire well can reduce rattles and improve sound quality. Custom-fabricating a more enclosed enclosure within the spare tire well can also improve bass response. However, this can significantly reduce spare tire storage space.

4. Signal Source Improvement

Using a high-quality signal source, such as a head unit with dedicated subwoofer outputs, can improve the overall sound quality. Adding a line output converter (LOC) can improve the signal quality when using high-level inputs.

Troubleshooting Common Issues

Here are some common issues and their potential solutions:

Weak Bass: Check the amplifier's gain settings, crossover settings, and wiring connections. Ensure the subwoofer is properly matched to the amplifier's impedance.

Rattles: Add dampening material to the spare tire well and surrounding areas. Secure all wiring harnesses.

Distortion: Reduce the amplifier's gain or the head unit's volume. Check for loose connections.

No Sound: Check the fuse for the amplifier. Verify the power, ground, and signal connections.

Conclusion

The Nissan Murano's spare tire subwoofer system is a testament to innovative automotive engineering. By cleverly utilizing existing space, Nissan created a hidden subwoofer system that enhances the vehicle's audio experience without sacrificing practicality. While it may not deliver the bone-rattling bass of a dedicated aftermarket system, it provides a refined and integrated solution for adding low-end frequencies to the Murano's soundscape. Understanding the design and function of this system allows enthusiasts to further optimize its performance through carefully selected modifications and upgrades, resulting in an even more immersive and enjoyable audio experience. The combination of the right placement and the correct design ensures the best performance of the vehicle's acoustics, and allows the listener to feel the bass without having to sacrifice storage.