KICKER KickerBDL241102-63
Kicker KS-Series 6x9 Coaxial Speakers Instruction Manual
Model: 51KSC6904
Introduction
This manual provides detailed instructions for the installation, operation, and maintenance of your Kicker KS-Series 6x9 Coaxial Speakers (Model 51KSC6904). Please read this manual thoroughly before attempting installation or operation to ensure proper use and to maximize the performance and longevity of your speakers.
Important Safety Information
- Professional Installation Recommended: For optimal performance and safety, it is highly recommended that these speakers be installed by a qualified car audio professional.
- Power Handling: Ensure your amplifier's power output matches the recommended power handling of these speakers to prevent damage. Overpowering or underpowering can lead to speaker failure.
- Wiring: Always use appropriate gauge wiring for speaker connections. Incorrect wiring can cause overheating or damage to your audio system.
- Ventilation: Ensure adequate ventilation around the speakers and amplifier to prevent overheating.
- Hearing Protection: Prolonged exposure to high volume levels can cause permanent hearing damage. Use caution when adjusting volume.
Package Contents
Before beginning installation, please verify that all the following items are included in your package:
- 2 x Kicker 51KSC6904 KS-Series 6x9" Coaxial Speakers
- 2 x 1" Silk-dome Tweeters (integrated)
- 2 x Speaker Grilles
- Mounting Hardware (screws, clips)
- 1 x Kicker Branded Can Koozie (bundle accessory)

Image: Pair of Kicker KS-Series 6x9 Coaxial Speakers with grilles.

Image: One Kicker KS-Series 6x9 Coaxial Speaker with its protective grille.

Image: One Kicker KS-Series 6x9 Coaxial Speaker without its grille, showing the cone and tweeter.

Image: A single protective grille for the Kicker KS-Series 6x9 speaker.

Image: Kicker branded can koozie, included as a bundle accessory.
Installation Guide
Mounting Considerations
The Kicker KS-Series speakers feature a thin-mount design, allowing them to fit easily behind most factory grilles and in various vehicle applications. Before mounting, ensure the chosen location provides sufficient clearance for the speaker's depth and diameter.
- Mounting Hole Diameter: 5-11/16 x 8-7/16 inches (14.45 x 21.43 cm)
- Top Mount Depth: 3-3/16 inches (8.1 cm)
- Bottom Mount Depth: 3-11/16 inches (9.37 cm)
- Tweeter Protrusion: 1/16 inch (0.16 cm)
Use the provided mounting hardware to secure the speakers firmly in place. Avoid over-tightening screws, which can damage the speaker frame.
Wiring Instructions
These speakers have a rated impedance of 4 ohms. Connect the speakers to an amplifier that is stable at a 4-ohm load and provides a recommended power output of up to 150 watts RMS per channel. Ensure correct polarity (+ to + and - to -) when connecting the speaker wires to both the speaker terminals and the amplifier terminals. Incorrect polarity can lead to reduced bass response and poor sound imaging.
It is recommended to use high-quality speaker wire of appropriate gauge (e.g., 16-gauge or thicker) for optimal power transfer and sound quality.
Operation
Once installed, connect your audio source to the amplifier. Start with the amplifier's gain settings at their minimum and gradually increase them until the desired volume is achieved without distortion. These speakers are designed to deliver clear and detailed audio reproduction across a wide frequency range.
Break-in Period: Like many audio components, these speakers may benefit from a break-in period. Play them at moderate volumes for several hours before attempting to play them at their maximum capabilities. This allows the speaker's suspension components to loosen and perform optimally.
Maintenance and Care
- Cleaning: Use a soft, dry cloth to clean the speaker grilles and surrounds. Avoid using harsh chemicals or abrasive cleaners.
- Environmental Conditions: While designed for automotive use, avoid exposing the speakers to excessive moisture, extreme temperatures, or direct sunlight for prolonged periods, as this can degrade materials over time.
- Inspection: Periodically inspect speaker cones and surrounds for any signs of damage or wear.
Troubleshooting
If you experience issues with your Kicker KS-Series speakers, refer to the table below for common problems and their solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound from speakers | Loose or disconnected wiring Amplifier not powered on Incorrect input selection on head unit | Check all speaker and amplifier connections Verify amplifier power and fuse Ensure correct audio source is selected |
| Distorted or unclear sound | Amplifier gain set too high Speaker wires shorted Damaged speaker cone/surround | Reduce amplifier gain Inspect wiring for shorts Contact Kicker support for speaker inspection/replacement |
| Weak or no bass | Incorrect speaker polarity Crossover settings incorrect Insufficient amplifier power | Verify speaker wire polarity Adjust head unit or amplifier crossover settings Ensure amplifier provides adequate power |
| Intermittent sound | Loose connections Overheating amplifier | Check all wiring connections Ensure proper ventilation for amplifier; reduce volume |
Technical Specifications
| Feature | Specification |
|---|---|
| Speaker Design | 2-Way Coaxial |
| Woofer Size | 6x9 inches |
| Tweeter Size | 1 inch |
| Rated Impedance | 4 Ohms |
| Recommended Amplifier Power (RMS) | 150 Watts |
| Sensitivity | 92 dB |
| Frequency Response | 30-21k Hz |
| Mounting Hole Diameter | 5-11/16 x 8-7/16 inches (14.45 x 21.43 cm) |
| Top Mount Depth | 3-3/16 inches (8.1 cm) |
| Bottom Mount Depth | 3-11/16 inches (9.37 cm) |
| Tweeter Protrusion | 1/16 inch (0.16 cm) |
| Woofer Material | Polypropylene with Rubber Surrounds |
| Tweeter Material | Silk-dome |
| Item Weight | 15.9 pounds (7.21 kg) |
| Package Dimensions | 18.63 x 12 x 4.44 inches (47.32 x 30.48 x 11.28 cm) |
Warranty and Customer Support
Kicker products are designed for durability and performance. For specific warranty terms and conditions, please refer to the warranty card included with your product or visit the official Kicker website. Keep your proof of purchase for warranty claims.
If you require technical assistance, troubleshooting beyond this manual, or warranty service, please contact Kicker customer support through their official website or authorized service centers. Provide your product model number (51KSC6904) and a detailed description of the issue when contacting support.
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