How to Wire Your Subwoofers to the Correct Impedance for Your Amplifier

Wiring a subwoofer to an amplifier comes down to one thing: impedance. Get it right and your amp delivers full power to your sub. Get it wrong and you're either leaving power on the table or putting your amplifier into protect. When it comes to subwoofers, the choices can be confusing — single or dual voice coil, 2 ohm or 4 ohm, series or parallel wiring. The answer to which is best really depends on your amplifier. Understanding your amp's specifications before you buy a sub is going to save you a lot of headaches when it comes time to install.

What Is a Voice Coil?

A voice coil is a magnetic winding — an internal part of a subwoofer that connects to the cone as well as to the input terminals on your subwoofer. As an electrical current is passed from the amplifier into the subwoofer, a magnetic field is generated around this voice coil. That field interacts with the magnetic field created by the subwoofer's magnet, causing the subwoofer to move according to the signal coming in from the amplifier.

Know your amp first Some amplifiers are 2 ohm stable, some are 1 ohm stable, some are 4 ohm stable. Know that information before you buy a sub. It's always best to get your amplifier first, then match your subs to it — if you buy subs first, you may not be able to find an amplifier that works at the impedance you need.

For the examples below, we'll use an amplifier rated at 250W x 1 at 4 ohms and 500W x 1 at 2 ohms — a typical mono subwoofer amplifier.

Single Voice Coil (SVC) Subwoofers

A single voice coil subwoofer has one winding, so the impedance is fixed. You have one wiring option: connect speaker wire directly from the amplifier to the sub's terminal cup.

Scenario 1 — One Single 4-ohm SVC Sub

A single 4-ohm SVC sub rated at 250W RMS. Our amplifier does 250W at 4 ohms. Connect speaker wire positive to positive, negative to negative. The amplifier sees 4 ohms and delivers its full 250W to the sub — a perfect match.

1 × SVC 4Ω → 4 ohms → 250W → perfect match

Scenario 2 — Two Single 4-ohm SVC Subs (Parallel)

Two 250W SVC 4-ohm subs. We want 500W total — our amp does 500W at 2 ohms, so we need to get to 2 ohms. Wire in parallel: connect both positives together, both negatives together, then to the amplifier. Two 4-ohm subs in parallel equals 2 ohms total.

2 × SVC 4Ω in parallel → 2 ohms → 500W total → 250W per sub

Scenario 3 — Two Single 4-ohm SVC Subs (Series)

Wiring those same two subs in series — negative from one sub to the amp, positive from the other sub to the amp, then link the positive and negative between the two subs — results in 8 ohms. Working backwards from our amp specs: at 4 ohms we get 250W, at 2 ohms 500W, so at 8 ohms we'd get roughly 125W. That's not enough to power two 250W subs.

2 × SVC 4Ω in series → 8 ohms → ~125W → not recommended

Parallel wiring formula Total Impedance = Sub Impedance ÷ Number of Subs

Dual Voice Coil (DVC) Subwoofers

Common misconception Because a subwoofer has two voice coils does not mean it can handle twice the power of a single voice coil. A 9500W single 4-ohm sub does the same 9500W that a dual 4-ohm sub does. The advantage of a dual voice coil is better wiring options — especially in a single sub scenario.

Scenario 4 — One Dual 4-ohm DVC Sub (Parallel)

A dual 4-ohm DVC sub rated at 500W RMS. Our amp does 500W at 2 ohms. Wire the two voice coils in parallel: connect both positives together, both negatives together, send to the amplifier. Two 4-ohm voice coils in parallel equals 2 ohms — same math as two separate subs, just both coils are on the same sub. Single subwoofer, 500W, 2 ohms. Perfect.

1 × DVC 4Ω wired in parallel → 2 ohms → 500W → perfect match

Scenario 5 — One Dual 4-ohm DVC Sub (Series)

Wire the same DVC sub in series — negative of one coil to positive of the other, then the remaining positive and negative to the amplifier — and you get 8 ohms. At 8 ohms our example amplifier only delivers around 125W to a 500W sub. Not the way to go.

1 × DVC 4Ω wired in series → 8 ohms → ~125W → not recommended

Dual 2-Ohm DVC Subwoofers

A dual 2-ohm DVC subwoofer gives you two options: 1 ohm (parallel) or 4 ohms (series). This is why knowing your amplifier's impedance stability matters before you buy.

Scenario 6 — Dual 2-ohm DVC Wired in Parallel (1 ohm)

Wire the two 2-ohm coils in parallel and you get 1 ohm. If your amplifier in our example is only 2 ohm stable, connecting in this fashion will cause the amplifier to go into protect and you won't get the performance you want.

1 × DVC 2Ω in parallel → 1 ohm → amp goes into protect on a 2Ω-stable amp

Scenario 7 — Dual 2-ohm DVC Wired in Series (4 ohm)

Wire the two 2-ohm coils in series — positive of one to the negative of the other, then the remaining positive and negative to the amplifier — and you get 4 ohms. The sub would perform on our amplifier at 4 ohms, but you'd only get 250W from a 500W-capable amp. You wouldn't be maximizing the potential of the sub.

1 × DVC 2Ω in series → 4 ohms → 250W → works but not maximized

Quick Reference: Wiring Summary

Configuration	Wiring	Ohms	Power (example amp)	Verdict
1 × SVC 4Ω	Direct	4Ω	250W	Good
2 × SVC 4Ω	Parallel	2Ω	500W	Best
2 × SVC 4Ω	Series	8Ω	~125W	Avoid
1 × DVC 4Ω	Parallel	2Ω	500W	Best
1 × DVC 4Ω	Series	8Ω	~125W	Avoid
1 × DVC 2Ω	Parallel	1Ω	Amp protect	Avoid*
1 × DVC 2Ω	Series	4Ω	250W	OK

*1 ohm wiring is valid if your amplifier is 1 ohm stable — always check your amp's specs.

Bottom line For a 500W amplifier stable at 2 ohms, a dual 4-ohm DVC or two single 4-ohm SVC subs wired in parallel will get you the best performance. This approach can be applied to any subwoofer and amplifier combination. To see more wiring diagrams, visit the MTX Support Library or use the Subwoofer Wiring Calculator.

Frequently Asked Questions

What happens if I wire my subwoofer at too low an impedance?

If you wire your subwoofer below your amplifier's minimum stable impedance, the amp will typically go into protect mode and shut down. In some cases it can overheat or fail permanently. Always check your amplifier's minimum ohm rating before wiring.

Is a dual voice coil subwoofer better than a single voice coil?

Not inherently — a dual voice coil sub doesn't produce better sound or handle more power than the same sub with a single voice coil. The advantage is wiring flexibility. A DVC sub gives you two impedance options, which makes it easier to match your amplifier's optimal load.

Should I buy my subwoofer or my amplifier first?

Buy your amplifier first. Once you know what impedance loads your amp supports and how much power it delivers at each, you can choose a subwoofer — or a combination of subwoofers — that lets you hit that optimal impedance. Buying subs first can leave you unable to find an amp that works at the impedance you end up with.

Can I wire a 4 ohm subwoofer to a 2 ohm amplifier?

Yes — a 4 ohm sub is within the safe operating range of a 2 ohm stable amp. The amplifier will simply deliver less power than its rated 2 ohm output. If you want to hit the amp's full power rating, you need to wire your sub or subs so the total impedance equals 2 ohms.

What is the difference between series and parallel wiring for subwoofers?

Parallel wiring lowers the total impedance — useful when you need to match a lower-ohm amp output. Series wiring raises the total impedance — typically used when you need to avoid going below your amp's minimum load. For most car audio setups with a mono amp, parallel wiring is the right choice to maximize power.

How to Wire Your Subs
to the Right Impedance

What Is a Voice Coil?

Single Voice Coil (SVC) Subwoofers

Dual Voice Coil (DVC) Subwoofers

Dual 2-Ohm DVC Subwoofers

Quick Reference: Wiring Summary

Frequently Asked Questions

Next Steps

How to Wire Your Substo the Right Impedance

What Is a Voice Coil?

Single Voice Coil (SVC) Subwoofers

Dual Voice Coil (DVC) Subwoofers

Dual 2-Ohm DVC Subwoofers

Quick Reference: Wiring Summary

Frequently Asked Questions

Next Steps

How to Wire Your Subs
to the Right Impedance