Wiring a subwoofer to an amplifier means matching the sub’s final impedance to the amp’s stable load and connecting each terminal with correct polarity.
For the full breakdown, see our best Amp For Car Subs guide.
Whether you’re learning how to wire subs to amp for your first car audio build or revisiting the basics, the process starts with two details: your sub’s voice coil configuration and your amp’s stable impedance. Connect positive to positive and negative to negative for standard parallel wiring, or use series wiring when you need a higher total impedance. Get these right and the rest of the install follows cleanly.
What Voice Coil Type Does Your Sub Have?
The wiring diagram you need depends on whether your subwoofer is single voice coil (SVC) or dual voice coil (DVC). Soundstream’s subwoofer wiring guide frames the entire wiring choice around this distinction because it determines how many terminal pairs you’re working with and how you can arrange them.
An SVC sub has one pair of terminals — one positive, one negative. A DVC sub has two pairs, giving you more flexibility to reach different final impedance loads. If you’re wiring multiple subs, you also need each sub’s individual impedance per coil (usually 1, 2, or 4 ohms) and whether each is SVC or DVC. Knowing this before you pick a diagram saves you from buying the wrong amplifier or wiring a load the amp can’t handle.
Series or Parallel — Which Wiring Pattern Fits?
Once you know your coil type and the target impedance for your amp, you choose parallel wiring, series wiring, or a combination of both for multiple DVC subs. Parallel wiring lowers the total impedance; series wiring raises it. The goal is to match the final impedance to what the amplifier is rated for at RMS power — MTX’s wiring diagrams page emphasizes using RMS ratings only and warns against relying on MAX or PEAK numbers when matching amp and subs.
| Voice Coil Setup | Wiring Method | Final Impedance (4-ohm coils) |
|---|---|---|
| Single SVC 4-ohm | Wire directly to amp | 4 ohms |
| Single DVC 4-ohm (parallel) | Both positives together, both negatives together | 2 ohms |
| Single DVC 4-ohm (series) | Positive of coil 1 to negative of coil 2 | 8 ohms |
| Two SVC 4-ohm (parallel) | All positives together, all negatives together | 2 ohms |
| Two SVC 4-ohm (series) | Positive of sub 1 to negative of sub 2 | 8 ohms |
| Two DVC 4-ohm (parallel/parallel) | All coils in parallel | 1 ohm |
| Two DVC 4-ohm (series/parallel) | Each sub in series, subs in parallel | 4 ohms |
If you’re choosing an amplifier to match your subs, our roundup of the best amps for car subs can help you find a stable, well-rated option at the power level you need.
Running Power, Ground, and Signal to the Amp
In a car installation, wiring the sub is only half the job — the amp also needs fused power, a solid ground, and a signal source. Disconnect the battery’s negative terminal before routing any high-current wiring to reduce shock and short-circuit risk.
Run a fused power wire from the battery positive through a firewall grommet, placing the inline fuse within 18 inches of the battery post. For a 500-watt amp, 4-gauge wire is the recommended minimum, and the ground wire should match that gauge, stay under 3 feet long, and attach to clean, unpainted bare metal on the chassis — a poor ground is the most common cause of noise and weak output.
Connect the remote turn-on lead from the head unit to the amp’s remote terminal. If your factory stereo lacks a dedicated RCA sub output, use high-level speaker inputs or install a line output converter. Finally, wire the amp’s output terminals to the sub terminals with correct polarity, reconnect the battery, and test at low volume before finalizing cable management.
Double-check that your final impedance matches the amp’s RMS rating, verify all connections are tight and polarity is correct, and confirm the ground is on clean bare metal. A properly wired sub setup delivers clean bass without risking your gear.
FAQs
What gauge wire should I use for a 500-watt amp?
4-gauge power wire is the recommended minimum for a 500-watt amplifier in a car audio system. The ground wire should be the same gauge as the power wire and kept under 3 feet in length, attached to bare metal on the chassis.
Can I wire a dual voice coil sub to 2 ohms?
Yes — wire both voice coils in parallel by connecting the positive terminals together and the negative terminals together. A DVC 4-ohm sub wired this way presents a 2-ohm load to the amplifier, provided the amp is stable at 2 ohms.
What happens if I wire a sub out of phase?
Reversing polarity at one sub while others are wired correctly causes the out-of-phase sub to move opposite the others, canceling bass output. You’ll hear noticeably weaker, thinner bass. Fix it by swapping the positive and negative connections on that sub.
References & Sources
- MTX Audio. “Wiring Diagrams.” Provides subwoofer wiring diagrams and emphasizes using RMS power ratings over MAX/PEAK ratings for amp matching.