How to Wire Subwoofers: A Step-by-Step Guide for Car Audio Enthusiasts
Wiring subwoofers can be a daunting task for car audio enthusiasts, but with the right knowledge and guidance, it becomes a straightforward process. This guide will walk you through the entire process of wiring subwoofers in your car, from understanding ohm loads to making the final connections.
Understanding Impedance and Ohm Loads
Before you start wiring, you need to understand impedance — measured in ohms (Ω). Impedance affects how much power your amplifier delivers to your subwoofers. Most car amplifiers are most powerful at 1-2 ohms.
Series vs Parallel Wiring
Parallel wiring connects all positive terminals together and all negative terminals together. This lowers impedance and gives the amplifier more power to work with.
Series wiring connects positive to negative in a daisy-chain. This raises impedance and reduces power delivery but is cooler and more stable for some amplifiers.
Dual Voice Coil (DVC) Subwoofers
DVC subwoofers have two sets of terminals, giving you more wiring options. Two 4-ohm coils wired in parallel = 2 ohms. Wired in series = 8 ohms.
Subwoofer Wiring Diagram
The diagram below shows the most common wiring configurations for single and dual voice coil subwoofers. Use it as a quick reference when planning your build:
What You'll Need
- Speaker wire or OFC wire (appropriate gauge for your power level)
- Wire stripper and crimping tool
- Ring terminals and butt connectors
- Multimeter (to verify final impedance)
- A high output alternator if your system is 500W RMS or more — see Car Audio Alternator Upgrade Guide
Step-by-Step Wiring Instructions
Step 1: Calculate Your Target Impedance
Check your amplifier's power ratings at different ohm loads. Most mono amps are rated at 1 ohm (maximum power) and 2 ohms. Choose the impedance your amp handles reliably at full power.
Step 2: Choose Your Wiring Configuration
Based on the number of subwoofers, their type (SVC or DVC), and their individual impedance, select a wiring diagram that achieves your target final impedance. Parallel = lower ohms (more power). Series = higher ohms (more stable).
Step 3: Make the Connections
Strip 1/2 inch of insulation from each wire end. Connect positive terminals to the amplifier's positive speaker output and negative to negative. For multiple subs, daisy-chain according to your chosen configuration.
Step 4: Verify with a Multimeter
Before powering on, use a multimeter set to ohms to measure the resistance at the amplifier's speaker terminals with all subs connected. Confirm it matches your target impedance.
Step 5: Set Amplifier Controls
Set the low-pass crossover to 80-100Hz. Set gain correctly using test tones — never by ear at maximum volume.
Power Requirements and Alternator Upgrade
Every amplifier in your system draws current from your vehicle's electrical system. A 1,000W RMS amplifier draws approximately 80–100 amps at full output. If your total system is 500W or more, your factory alternator may not be able to keep up.
Signs you need an alternator upgrade: headlights dimming during bass hits, voltage dropping below 13V while playing music, amplifiers cutting out or going into protection.
JS Alternators builds direct-fit high output alternators (250-370A) for all major vehicle platforms: Shop High Output Alternators by Vehicle →
Frequently Asked Questions
How do I wire subwoofers to an amplifier?
Connect the amplifier's speaker output terminals to the subwoofer voice coil terminals according to your wiring configuration. Verify polarity and final impedance with a multimeter before powering on.
What ohm load should I wire my subwoofers to?
Target 1-2 ohms for maximum power from most mono amplifiers. Check your amp's specifications — some are more stable at 2 ohms and sacrifice little power versus 1 ohm.
Do I need a high output alternator for subwoofers?
If your system is 500W RMS or more, yes. A 1,000W amp draws roughly 100A. Combined with factory loads, this exceeds most stock alternators. See: How Many Amps Do I Need?