How To Wire Car Speakers – Simple & Effective Guide
If you’re looking to wire car speakers yourself, you’re in the right place. Wiring car speakers may seem intimidating at first, but with the right guidance, it’s a simple and straightforward process. Whether you’re upgrading your factory audio system or installing an entirely new setup, this guide will walk you through the essential steps and provide helpful tips to ensure a clean and effective installation.
Why Understanding Speaker Wiring Matters
Properly wiring your car speakers is crucial for achieving the best sound quality. Speakers operate on alternating current (AC) voltage, which differs from the direct current (DC) voltage that powers your car’s amplifier and head unit. This fundamental difference impacts how speakers produce sound and how they interact with other components in your car’s audio system.
Additionally, understanding the nuances of speaker wiring—like polarity and phasing—can help you fine-tune your audio experience, ensuring your system performs at its best.
Tools and Materials You’ll Need
Before you start wiring your car speakers, gather the necessary tools and materials:
- Speaker wire (16 or 18-gauge is typically sufficient)
- Wire strippers
- Electrical tape or heat shrink tubing, zip ties (optional for a cleaner install)
- Multimeter (just in case you need to test something, but likely not required for a simple speaker install)
- Crimp connectors
- Crimpers
- Screwdrivers
- Panel removal tool (optional, for removing door panels)
Step 1: Understand Speaker Polarity
Every speaker has two terminals: positive (+) and negative (-). Correctly wiring the polarity ensures consistency in your install. That’s basically it. You aren’t going to fry anything if the speakers are wired out of phase. In fact, this can be used as a tuning technique (mainly before DSPs became popular).
If speakers are wired in phase (all positive terminals connected to the amplifier’s positive outputs and all negative terminals connected to negative outputs), the speakers will all be in electrical phase with each other. But acoustically, the sound will be off due to different distances that each speaker is located. This is where DSPs come in – more on that later. Let’s stick to speaker installation here.
What Happens If Speakers Are Wired Out of Phase?
Wiring a speaker out of phase (positive to negative and vice versa) will not damage the speaker in any way. However, it can in some cases cause the audio to sound thin or “off” due to destructive interference between sound waves.
Interestingly, wiring speakers out of phase was a common technique used in the pre-DSP era to fine-tune a system. For example, phasing adjustments were sometimes made to improve imaging or to compensate for less-than-ideal speaker placement.
The exception is subwoofers, which produce low frequencies and are often placed close together. Wiring subwoofers out of phase can result in a significant reduction in bass output, as the opposing sound waves cancel each other out. I’ve also noticed similar when adding new 6.5″ speakers to Jeep rollbars since they are fairly close together and share basically the same airspace.
Step 2: Reuse / Measure and Cut the Speaker Wire
Reusing the factory speaker wiring in your car is more than adequate in 95% of installations. If the wire appears to be in good condition, I’d just use that instead of run new wire to every speaker. Too much work for no reason. The exception is super old cars with questionable wiring. Another exception is super high power systems where you need bigger wire. This is very unlikely in most cases since speakers don’t carry near as much current as DC power systems in a car. Another thing to note is that pretty much all factory wiring is pure copper. A lot of aftermarket wiring is copper clad aluminum (CCA) or a mix of aluminum and copper. You can definitely find aftermarket copper wire pretty easily though.
If you do run new wire, be sure to measure the distance between your amplifier or head unit and each speaker. Add a few extra inches to account for routing and connections. Cut the speaker wire to the appropriate length and strip about 1/2 inch of insulation from both ends using wire strippers to prepare it for the speaker terminals.
Choosing the Right Wire Gauge
For most car speaker installations, 16-gauge or 18-gauge speaker wire is sufficient. However, for higher-powered systems or longer runs (e.g., in SUVs or trucks), 14-gauge wire may be a better choice.
Step 3: Route the Speaker Wire
Carefully route the speaker wire through your vehicle, avoiding sharp edges, moving parts, or areas that could cause wear and tear. Use existing factory wire harnesses or channels when possible for a clean installation. Secure the wire with zip ties to prevent it from moving or getting damaged.
Step 4: Connect the Speaker Wire to the Speakers
- Identify the positive and negative terminals on your speakers. These are usually marked with a + and – or are color-coded (e.g., red for positive and black for negative).
- If reusing factory speaker wire, especially when using head unit power, you may need to check wiring manuals to make sure you get positive and negative right.
- Connect the positive wire to the positive terminal and the negative wire to the negative terminal.
- If your speaker has spring-loaded terminals, simply insert the stripped wire.
- If your speaker has tabs, I recommend using crimp on female spade connectors. I do not recommend soldering directly to speakers for various reasons.
- Ensure the connections are tight and secure to prevent signal loss or distortion.
Step 5: Connect the Speaker Wire to the Amplifier or Head Unit
At the other end of the wire, connect the positive and negative leads to the corresponding terminals on your amplifier or head unit. Most modern car audio systems will have labeled terminals to make this process straightforward. If you have an aftermarket head unit, you’ll want to use a car specific wiring harness which is color coded and makes this process super simple.
Polarity Pro Tips:
If your speaker terminal positive and negative aren’t labeled, and you want to be sure your polarity is correct, here’s a few quick tips:
Battery Method
Use a 9-volt battery (or a speaker polarity tester – basically a 9V battery in a box with LEDs) (or a drill battery if you’re brave – I used to do this when I had a 12V drill) to verify the polarity of your connections. For the 9-volt battery method:
- Cut a little speaker wire pigtail. Connect to the speaker on one end. Briefly touch the positive and negative speaker wires to the corresponding terminals on the battery.
- Observe the movement of the speaker cone:
- If the cone moves outward, the polarity is correct.
- If the cone moves inward, the polarity is reversed.
Visual Methods
- The larger of the 2 terminals is almost always (maybe even 100% always) positive. And the smaller is negative.
- If they are the same size, try this: When looking at the back of the speaker, the terminal on the right side is usually positive. This isn’t always the case. But if you are replacing all speakers and use this reference, everything will still be in phase. Which is the goal – for all speakers to be in phase with each other. Doesn’t matter if you swap wires if you do it the same way on all speakers.
Step 6: Fine-Tune Your System
Once all the speakers are wired and installed, play some music to test the sound quality. Walk around the vehicle and listen for any inconsistencies. If you notice any strange audio effects, double-check your connections and polarity.
Tips for a Successful Installation
- Label Your Wires: Use small pieces of tape to label each wire during the installation process to avoid confusion. If you’re running your own wire, almost all aftermarket speaker wire is easily identifiable.
- MYTH: “Avoid Running Wires Near Power Cables: This prevents electrical interference, which can cause noise in your audio system.” Bogus in the case of speaker wires. Sometimes you can see some interference with running RCAs next to power cables. But it’s usually due to using the wrong type of RCAs (yes there’s different types – more on this later, though).
- Double-Check Polarity: Mainly if you plan on doing any tuning down the line. If you go to set time alignment (using the distance method – not audibly) and one speaker is out of phase, your time alignment will be off by 180° and you may not even really notice. But you may wonder why it doesn’t sound as good as you think it should.
- Bundle Excess Wire: If you have extra wire, coil it neatly and secure it with zip ties to avoid a messy installation. I like to secure with factory wiring looms whenever possible. Not only does it look nicer, it makes sure you won’t have any interferences – ya know like windows chopping a wire in half… ask me how I know.
Common Mistakes to Avoid
- Using the Wrong Wire Gauge: Too thin a wire can cause too much resistance, reducing the quality of your audio signal. Again, pretty unlikely in the case of most speaker installations.
- Ignoring Polarity: While wiring out of phase won’t damage the speakers, it can cause some issues later on. Especially if you plan on tuning.
- Failing to Secure Wires or Improper Routing: Loose or exposed wires can lead to shorts or damage over time. See above lol.
- Skipping Testing: Always test your connections before reassembling panels or securing wires permanently.
Understanding AC Voltage in Speakers
It’s essential to remember that car speakers operate on AC voltage, which allows them to vibrate back and forth to produce sound. This is different from the DC voltage used to power your car’s amplifier and head unit. AC voltage ensures that the speaker diaphragm moves in both directions, creating sound waves. This is why wiring speakers backwards won’t cause any damage.
Conclusion
Wiring car speakers doesn’t have to be complicated. By understanding the basics of speaker polarity, AC voltage, and the tools needed, you can confidently tackle your next car audio project. Remember, attention to detail and proper testing are the keys to a clean and effective installation. Whether you’re upgrading your sound system or building a custom setup, this guide has you covered for a successful and satisfying experience.
Ready to take your car audio to the next level? Share your thoughts or questions below—we’re here to help you wire with confidence!