Choosing an amplifier for your subwoofers isn’t simply a matter of finding an amplifier with a similar wattage rating. To build a system that performs properly and reliably, you need to match three important things:

RMS Power + Voice Coil Configuration + Final Impedance

Getting these right helps your subwoofers receive the power they need while keeping the amplifier operating within its designed impedance range.

Start With RMS Power — Not Maximum Power

When matching an amplifier and subwoofer, use the RMS power ratings.

RMS is the continuous power rating and is the more useful specification when designing a system. Peak or MAX ratings should not be used as the primary number for matching an amplifier to a subwoofer.

For example, if you have:

2 subwoofers rated at 800 watts RMS each

their combined RMS power handling is:

800W + 800W = 1,600 watts RMS

You would then look for an amplifier capable of providing an appropriate amount of RMS power to the pair at an impedance the subwoofers can actually be wired to.

Impedance Is Just as Important as Wattage

Subwoofer impedance is measured in ohms (Ω).

An amplifier’s power output changes depending upon the impedance connected to it.

For example, an amplifier might be rated:

500W RMS @ 4Ω
900W RMS @ 2Ω
1,500W RMS @ 1Ω

These numbers are examples only, but they demonstrate an important point:

You cannot say an amplifier produces a certain amount of power without also specifying the impedance at which it produces that power.

The subwoofer configuration determines the final impedance the amplifier will see.

SVC vs. DVC Subwoofers

A Single Voice Coil (SVC) subwoofer has one voice coil and one set of positive and negative terminals.

A Dual Voice Coil (DVC) subwoofer has two voice coils and two sets of terminals.

Dual voice coils provide additional wiring flexibility.

For example:

One DVC 2Ω subwoofer can typically be wired to:

1Ω — coils wired in parallel
or
4Ω — coils wired in series

One DVC 4Ω subwoofer can typically be wired to:

2Ω — coils wired in parallel
or
8Ω — coils wired in series

Adding multiple subwoofers creates additional possible final impedance configurations.

Example: Massive Audio GTX104H

The Massive Audio GTX104H is a 10-inch subwoofer rated at 600–800 watts RMS with dual 4Ω voice coils.

One GTX104H can therefore normally be configured as either:

2Ω with its coils wired in parallel

8Ω with its coils wired in series.

If you’re using two GTX104H subwoofers, their voice coils can be configured to create several possible final impedance loads.

The goal is to choose the configuration that provides an appropriate load for the amplifier while allowing the amplifier to deliver suitable RMS power to the subwoofers.

Example: Two DVC 4Ω Subwoofers

Suppose you’re installing:

2 × DVC 4Ω subwoofers rated at 800W RMS each

Total subwoofer RMS capability:

2 × 800W = 1,600W RMS

A common wiring configuration allows two DVC 4Ω subwoofers to present a 1Ω final load.

You could therefore look for a mono amplifier capable of delivering an appropriate amount of RMS power at 1Ω.

But there’s another important requirement:

The amplifier must be rated as stable at that impedance.

Never connect an amplifier to an impedance below its manufacturer’s minimum recommended load.

What If You Already Own the Amplifier?

Work backward.

First find the amplifier’s RMS ratings.

For example:

RMS @ 4Ω
RMS @ 2Ω
RMS @ 1Ω

Then determine:

1. The lowest impedance the amplifier is designed to support.

2. How much RMS power it produces at each supported impedance.

3. How many subwoofers you want to operate.

4. What voice-coil configuration will create the desired final impedance.

5. Whether the resulting amplifier RMS output is appropriate for the combined RMS capability of the subwoofers.

Multiple Subwoofers Should Normally Match

When multiple subwoofers share the same amplifier output, use matching subwoofers whenever possible.

Ideally they should have the same:

Model
Voice-coil configuration
Impedance
RMS power rating

Mixing different subwoofers can cause uneven power distribution and unpredictable results.

Don’t Forget the Vehicle’s Electrical System

Finding an amplifier and subwoofer combination that works electrically with each other doesn’t automatically mean the vehicle can properly support the amplifier.

Higher-power car audio systems can place substantial demands on the vehicle’s charging system.

Depending upon the amplifier, vehicle and intended listening level, upgrades may include:

Larger power and ground wiring
The Big 3 electrical upgrade
Additional battery capacity
AGM or lithium battery upgrades
A higher-output alternator

The vehicle’s year, make, model, engine and factory charging-system capability should be considered when planning a high-power audio system.

Information You Need Before Choosing an Amplifier

Before selecting an amplifier for your subwoofers, determine:

Subwoofer model — What exact subwoofer are you using?

Number of subwoofers — One, two, three, four?

RMS power — What is the RMS rating of each subwoofer?

Voice coils — SVC or DVC?

Voice-coil impedance — 1Ω, 2Ω, 4Ω, etc.?

Final impedance — What loads can the complete subwoofer system be wired to?

Amplifier RMS output — How much RMS power does the amplifier produce at that impedance?

Amplifier stability — Is the amplifier designed to operate at that impedance?

Vehicle electrical system — Can the vehicle reasonably supply the power required by the amplifier?

The Simple Rule

When matching subwoofers and amplifiers:

Don’t match watts alone.

Match:

Subwoofer RMS Power + Final Wired Impedance + Amplifier RMS Output at That Impedance

Then make sure the vehicle’s electrical system can support the resulting amplifier system.

Need Help Matching Your Massive Audio System?

If you’re unsure which Massive Audio amplifier or subwoofer combination is right for your vehicle, provide:

Year / Make / Model / Engine
Subwoofer model
Number of subwoofers
Amplifier model, if you already own one
Your goal — daily listening, sound quality, high-output/SPL, etc.

With that information, a more appropriate system recommendation can be made.

Important Installation Note

The information in this guide is intended as general system-design guidance. Vehicle electrical systems, installation methods, enclosure design and operating conditions can significantly affect system performance.

For high-power systems, Massive Audio recommends consulting an experienced professional car-audio installer who can evaluate the vehicle, electrical system, wiring, enclosure and intended system configuration before installation.

How to Match a Car Amplifier to Subwoofers