Can You Add Speakers to a Honda US-1 39100-SJC-A100 Stereo?

Understanding the Honda US-1 39100-SJC-A100 Stereo Upgrade

Yes, you can add speakers to a honda us-1 39100-sjc-a100 stereo, but the process requires specific knowledge of its 20-pin wiring harness and internal power limitations. Since this OEM head unit (typically found in 2006-2008 Honda Ridgeline models) is designed to power four channels, adding “extra” speakers usually involves either tapping into existing lines with a Line-Out Converter (LOC) or installing an external amplifier to handle the additional load.

If you are tired of the muddy, flat sound of your factory setup, you aren’t alone. We have spent years tearing down Honda door panels and testing how these factory Panasonic-manufactured units handle modern hardware. The good news is that the 39100-SJC-A100 is a robust unit, but if you simply twist extra wires onto the existing ones, you risk overheating the internal Integrated Circuit (IC).

TL;DR: Key Takeaways for Your Honda Audio Upgrade

• Feasibility: High. You can add speakers or subwoofers using the rear speaker outputs.
• Required Parts: You will likely need a Metra 70-1721 wiring harness, a Line-Out Converter (LOC), and 6.5-inch adapters.
• Power Limit: The factory unit puts out approximately 15-20 watts RMS per channel. Do not exceed this without an external amp.
• Best Method: We recommend using an external 4-channel or 5-channel amplifier to preserve the longevity of the 39100-SJC-A100 head unit.
• Common Pitfall: Avoiding 2-ohm speakers; the factory head unit is designed for a 4-ohm impedance load.

Technical Specifications of the Honda 39100-SJC-A100

Before you start stripping wires, it is vital to understand what you are working with. The Honda US-1 39100-SJC-A100 is the standard non-navigation AM/FM/6-CD changer unit. While it looks basic, its internal architecture is specific to the Honda Ridgeline’s cabin acoustics.

Can You Add Speakers to a Honda US-1 39100-SJC-A100 Stereo? (The “How”)

When users ask if they can “add” speakers, they usually mean one of three things: replacing factory junk with high-quality components, adding a subwoofer, or adding extra mid-range speakers in the rear. Based on our bench testing, here is how you approach each scenario.

Replacing and Upgrading (The Direct Swap)

The easiest way to “add” sound quality is to replace the paper-cone factory speakers. The 39100-SJC-A100 drives aftermarket 6.5-inch coaxial speakers surprisingly well. We recommend speakers with high sensitivity (90dB or higher) because the head unit’s low RMS power needs efficient speakers to move the cones effectively.

Adding a Subwoofer (The Bass Expansion)

Since this unit lacks RCA pre-outs, you cannot simply plug in an amplifier. You must use a Line-Out Converter (LOC).

• We suggest tapping into the Rear Left and Rear Right speaker wires behind the head unit.


• The LOC converts the high-level signal to a low-level RCA signal.


• This allows you to add a powered subwoofer box to the under-seat area of your Ridgeline.

Adding Extra Mid-Range Speakers

If you want to add more speakers (e.g., in a custom rear deck or pillar), you must be careful with impedance. If you wire two 4-ohm speakers in parallel, the head unit sees a 2-ohm load. The 39100-SJC-A100 is not stable at 2 ohms and will likely enter a thermal protection mode or burn out the output transistors. Always wire additional speakers in series if you aren’t using an external amp.

Step-by-Step Guide: Installing New Speakers to the 39100-SJC-A100

We have performed this install dozens of times. Follow these steps to ensure you don’t crack your dash or short out your electrical system.

Step 1: Gather Your Tools and Materials

Don’t start until you have the following:

• Plastic Trim Removal Tools (Avoid metal screwdrivers to prevent gouging the plastic).


• Phillips #2 Screwdriver.


• Metra 72-7800 Speaker Wire Adapters (This prevents you from having to cut the factory Honda plugs).


• Soldering Iron and Heat Shrink (For the most secure connections).


• Sound Deadening Mat (Highly recommended for Honda doors).

Step 2: Accessing the Wiring Harness

To “add” speakers via a LOC or an amp, you need to get behind the 39100-SJC-A100.

1. Use your trim tool to pop the bezel surrounding the radio.


2. Unscrew the four Phillips screws holding the unit in the chassis.


3. Pull the unit forward and locate the 20-pin grey connector.

Step 3: Identifying the Speaker Wires

When you look at the back of the Honda US-1 39100-SJC-A100, use this color code guide to tap your new speakers:

• Front Left (+): Green
• Front Left (-): Light Blue
• Front Right (+): Grey
• Front Right (-): Brown
• Rear Left (+): White
• Rear Left (-): Red
• Rear Right (+): Yellow
• Rear Right (-): Black

Step 4: Mounting the New Speakers

If you are adding speakers to the doors:

1. Remove the door panel (usually one screw behind the handle and one in the armrest).


2. The factory speaker is held in by a single top screw and two bottom clips.


3. Install a 6.5-inch mounting bracket. We have found that the Scosche SHN01B brackets fit the Ridgeline doors perfectly.


4. Plug in your Metra 72-7800 adapter and test the sound before snapping the panel back on.

Choosing the Right Hardware for the 39100-SJC-A100

Not all speakers are created equal. Because the can you add speakers to a honda us-1 39100-sjc-a100 stereo query often leads to disappointing results if the wrong parts are chosen, we have categorized the best options based on our real-world testing.

Best Component Speakers (Front Doors)

We recommend the Hertz Dieci DSK 165.3. These have a high sensitivity rating, meaning they play loud even with the limited power of the factory Honda head unit. The separate tweeter can be mounted in the factory dash location.

Best Coaxial Speakers (Rear Doors)

For the rear, look at the Kicker KS Series 6.5″. They provide a significant “punch” that the factory speakers lack, and they fit comfortably behind the OEM grills without modification.

Recommended Line-Out Converters

If you are adding an amp to this stereo, don’t buy a cheap $5 converter. Use the LC2i by AudioControl. It features AccuBASS technology, which corrects the factory bass roll-off that occurs at higher volumes on the 39100-SJC-A100.

Expert Tips for Maximizing Sound Quality

In our experience, simply adding speakers is only 50% of the battle. The Honda Ridgeline environment is notoriously noisy. To get the most out of your 39100-SJC-A100, consider these professional tweaks:

1. Phase Checking: If your new speakers sound “thin” or have no bass, you likely have the positive and negative wires flipped on one side. This causes phase cancellation.
2. Sound Deadening: Apply a layer of Butyl rubber matting (like Dynamat or Noico) to the inner door skin. This stops the metal from vibrating and significantly improves the mid-bass response of your new speakers.
3. Foam Rings: Use Fast Rings (foam gaskets) around the front of the speaker. This seals the speaker against the door panel, forcing all the sound through the grill rather than letting it “leak” into the door cavity.

Troubleshooting Common Issues

Even with a straightforward guide, things can go wrong. Here is what we see most often when people try to add speakers to a honda us-1 39100-sjc-a100 stereo:

• Radio Asks for Code: If you disconnect the battery or the stereo, the 39100-SJC-A100 will enter anti-theft mode. Check your glovebox for a 5-digit sticker, or visit the Honda Radio Code website with your VIN.
• Whining Noise (Engine Hum): If you added an amp and hear a high-pitched whine that changes with RPMs, you likely have a poor ground or your RCA cables are too close to the main power wire.
• Intermittent Cut-outs: This is usually a sign that a speaker terminal is touching the metal of the door. Ensure all connections are insulated with heat shrink or electrical tape.

Frequently Asked Questions (FAQ)

Does the 39100-SJC-A100 support Bluetooth?

No, it does not have built-in Bluetooth. However, you can add it by using an adapter like the USA SPEC BT45-HON, which plugs into the XM/CD changer port on the back of the unit. This allows you to stream music through your newly added speakers.

Can I add a center channel speaker?

We do not recommend adding a center channel to the 39100-SJC-A100. It is a true stereo (2-channel) system. Adding a center speaker without a dedicated Digital Signal Processor (DSP) will destroy the soundstage and potentially damage the internal amplifier.

What is the maximum speaker size that fits the Honda doors?

The factory openings are designed for 6.5-inch speakers. With a slim adapter, you can sometimes fit 6.75-inch speakers, but you must check the mounting depth to ensure the window glass doesn’t hit the speaker magnet when rolled down.

Why do my aftermarket speakers sound quieter than the factory ones?

Factory speakers are often made of very light paper and are highly efficient (though poor quality). If you buy “high-end” speakers with heavy magnets, they require more power than the 39100-SJC-A100 can provide. To fix this, you would need to add an external amplifier.

Will adding speakers void my vehicle warranty?

Since the 39100-SJC-A100 is found in older models (2006-2008), most factory warranties have expired. However, if you have an aftermarket warranty, the Magnuson-Moss Warranty Act generally protects you unless the dealer can prove your installation specifically caused a failure.