How to Wire Two Subwoofers? | Match the Load, Not the Size

Wire two subwoofers in parallel to halve the impedance, or in series to double it—always keep the final load inside the amplifier’s rated range.

Most wiring mistakes don’t come from getting the connections backwards. They come from feeding an amplifier a load it wasn’t built for. The way to wire two subwoofers is to start with each sub’s impedance and voice-coil count, then pick parallel or series wiring to land on a total load the amp can handle. That single decision drives every wire you run afterward.

First, know what you’re working with. Single-voice-coil subs have one pair of terminals and one fixed impedance. Dual-voice-coil subs have two pairs of coils, which can be wired together for different loads—that’s why DVC models dominate serious car systems. The right diagram always comes from coil count and impedance, never from sub size.

Match the Final Load to Your Amplifier

Your amplifier’s manual lists a minimum stable impedance, usually 2 or 1 ohm for car amplifiers and 4 or 8 ohms for home receivers. The combined load you build from two subs must not sit below that number. MTX’s wiring library and Crutchfield’s guidance both stress the same rule: match the final load to the amp’s supported impedance, or you risk overheating, distortion, and protection-mode shutdowns.

Here are the common final loads for two matching subs:

The bridged example matters for stereo amps running a single final load. Two DVC 4-ohm subs wired for a bridged 2-channel amp present a 4-ohm load, which most stable 2-channel amps handle comfortably. Check the amp’s bridged rating separately—bridging often raises the minimum impedance the amp can take.

If two subs read slightly different resting impedances, they still wire together fine; the final load lands close to the parallel or series calculation as long as both are the same nominal rating.

If you’re still picking the drivers themselves, our tested roundup of the best 2 8 inch subwoofers lists models that pair cleanly with the loads above.

Wiring Two Subwoofers: Parallel vs. Series

Parallel wiring lowers total impedance and is the go-to when your amp can deliver serious current into a low load. Keep the polarity strict—positive to positive, negative to negative—since a reversed voice coil cancels bass instead of adding it. The connection is simple: tie all positives together, tie all negatives together, and run the joined pair to the amp.

Series wiring raises total impedance and suits amps that need to see a higher load. The chain runs: amp positive to sub one positive, a jumper from sub one negative to sub two positive, then sub two negative back to the amp. Crutchfield’s subwoofer wiring diagrams map both paths coil-by-coil if you want a visual before cutting wire. In either scheme, check each sub’s resting impedance with a multimeter before final hookup; a healthy 4-ohm coil reads somewhere around 3.5 to 4.2 ohms.

Choose the scheme by what the amp can feed. Car amps built for low-ohm loads, such as Class D monoblocks rated down to 1 ohm, pair naturally with parallel wiring and DVC subs. Home receivers and smaller car amps usually expect 4 or 8 ohms, making series wiring or higher-impedance DVC configurations the safer route.

How Do You Wire Dual Voice Coil Subs?

Dual-voice-coil subs need one extra step before the two-sub wiring starts. Wire each sub’s two coils into a single pair of terminals first—parallel coils cut that sub’s impedance in half, series coils double it. Then treat each finished sub as a single-voice-coil unit and connect the two together in parallel or series, matching the same target load from the table above.

Measure each coil with a multimeter before the final hookup. A reading near the rated value confirms the coil is healthy and the wiring is correct, which saves you from hunting a wiring error after the amp is already connected.

You’ll also want the right supplies before you start: a multimeter for continuity and impedance checks, wire strippers, and speaker wire thick enough for the power your amp delivers. Crimp terminals or a soldering iron make lasting connections, and heat-shrink tubing over each splice keeps stray strands from touching metal.

Work in this order: check the amp’s minimum load, confirm each sub’s impedance and coil count, wire the coils on each DVC sub, join the two subs in parallel or series, then measure the final result before powering up. For powered home-theater subs, use a dedicated second sub output on the receiver when it exists—Audioholics notes newer receivers increasingly offer multiple sub outs, while older models may need a Y-splitter or daisy-chain on the sub’s inputs. Powered subs connect differently—the amp is built in, so you’re only running a signal cable, and the wiring rules above apply to passive subs driven by an external amplifier. Get these steps in the right order and two subs will play together cleanly for years.