How to Wire Subwoofers: Series vs. Parallel Wiring
Correctly wiring your subwoofers is one of the most important parts of designing a car audio system.
The way the voice coils and subwoofers are connected determines the final impedance (ohm load) presented to the amplifier.
That final impedance affects:
Amplifier power output
Amplifier current demand
Heat generation
System efficiency
Whether the amplifier can operate safely
Before wiring any subwoofer system, you should know the exact subwoofer model, voice-coil configuration, coil impedance and amplifier specifications.
What Is Impedance?
Speaker and subwoofer impedance is measured in ohms (Ω).
You will commonly see car audio subwoofers described as:
SVC 4Ω
DVC 2Ω
DVC 4Ω
An amplifier will also have RMS power ratings at specific impedances.
For example, an amplifier might be rated:
500 watts RMS @ 4Ω
900 watts RMS @ 2Ω
1,500 watts RMS @ 1Ω
These numbers are only examples, but they demonstrate why the final impedance matters.
The same amplifier can produce different amounts of power depending upon the impedance connected to it.
What Is Series Wiring?
When speaker voice coils are wired in series, their impedances are added together.
For example:
4Ω + 4Ω = 8Ω
or:
2Ω + 2Ω = 4Ω
A simple series connection looks like this:
Amplifier (+) → Voice Coil #1 (+)
Voice Coil #1 (-) → Voice Coil #2 (+)
Voice Coil #2 (-) → Amplifier (-)
The electrical signal travels through one voice coil and then through the next.
Example: DVC 4Ω Subwoofer Wired in Series
A DVC 4Ω subwoofer contains:
Voice Coil #1 = 4Ω
Voice Coil #2 = 4Ω
Wiring the two coils in series produces:
4Ω + 4Ω = 8Ω final impedance
Therefore:
One DVC 4Ω subwoofer wired in series = 8Ω
What Is Parallel Wiring?
When identical speaker voice coils are wired in parallel, the resulting impedance decreases.
For two identical loads:
Two 4Ω coils in parallel = 2Ω
Two 2Ω coils in parallel = 1Ω
A simple parallel connection looks like this:
Amplifier (+) → Both positive (+) voice-coil terminals
Amplifier (-) → Both negative (-) voice-coil terminals
Example: DVC 4Ω Subwoofer Wired in Parallel
A DVC 4Ω subwoofer contains two 4Ω voice coils.
Wiring them in parallel produces:
2Ω final impedance
Therefore:
One DVC 4Ω subwoofer wired in parallel = 2Ω
Example: DVC 2Ω Subwoofer Wired in Parallel
A DVC 2Ω subwoofer contains two 2Ω voice coils.
Wiring them in parallel produces:
1Ω final impedance
Therefore:
One DVC 2Ω subwoofer wired in parallel = 1Ω
Common Single-Subwoofer Configurations
One DVC 4Ω Subwoofer
Typical wiring options:
Series → 8Ω
Parallel → 2Ω
One DVC 2Ω Subwoofer
Typical wiring options:
Series → 4Ω
Parallel → 1Ω
This is why selecting a DVC 2Ω versus DVC 4Ω version of a subwoofer should be based on the amplifier and complete system design.
Wiring Two DVC 4Ω Subwoofers
Two DVC 4Ω subwoofers contain:
4 total voice coils
with each coil having a nominal impedance of 4Ω.
One of the most common configurations is to wire the coils and subwoofers so the amplifier sees approximately:
1Ω final impedance
This configuration is commonly used with a mono amplifier designed to operate at 1Ω.
However:
Never use a 1Ω configuration unless the amplifier is specifically rated as stable at 1Ω.
Wiring Two DVC 2Ω Subwoofers
Two DVC 2Ω subwoofers contain:
4 total 2Ω voice coils
A commonly used series/parallel configuration allows the pair to present approximately:
2Ω final impedance
This can be useful when an amplifier produces the desired RMS output at 2Ω.
Why Not Always Wire for the Lowest Possible Impedance?
It’s easy to assume:
Lower impedance = more amplifier power = better system
That isn’t necessarily true.
Lower impedance generally allows a compatible amplifier to deliver more power, but it can also increase:
Current demand
Amplifier heat
Demand on the vehicle’s charging system
Demand on the battery
Power and ground wiring requirements
The objective isn’t to achieve the lowest possible impedance.
The objective is to achieve the correct impedance for the amplifier and subwoofers being used.
Amplifier Minimum Impedance Is Critical
Every amplifier has a minimum impedance at which it is designed to operate.
For example:
If an amplifier is rated:
1Ω stable in mono operation
then a properly designed 1Ω subwoofer load may be acceptable.
If an amplifier specifies:
2Ω minimum
connecting a 1Ω load is not recommended.
Operating below the manufacturer’s minimum impedance can cause:
Excessive heat
Protection mode
Distortion
Clipping
Reduced reliability
Amplifier failure
Never select a wiring configuration without first checking the specifications for the exact amplifier.
Bridged Amplifiers Require Special Attention
When bridging channels on a multi-channel amplifier, minimum impedance requirements can change.
For example, an amplifier might be rated:
2Ω stable per channel in stereo
but:
4Ω minimum when bridged
This is because each amplifier channel effectively experiences part of the bridged load.
Therefore:
Never assume that an amplifier rated for 2Ω stereo operation can operate at 2Ω when bridged.
Check the manufacturer’s bridged RMS rating and minimum bridged impedance.
RMS Power Still Matters
Correct impedance doesn’t automatically mean the amplifier and subwoofer are a good match.
Suppose two subwoofers have a combined power handling capability of:
1,600 watts RMS
and can be wired to a 1Ω final impedance.
You still need to check how much power the amplifier produces at 1Ω.
If the amplifier produces:
1,500 watts RMS @ 1Ω
that may be a reasonable power match depending upon the specific products and application.
If the amplifier produces:
5,000 watts RMS @ 1Ω
the fact that both configurations are 1Ω doesn’t make them an appropriate match.
You must consider:
Final impedance AND RMS power.
Don’t Confuse Nominal Impedance With an Exact Resistance Reading
A subwoofer labeled 2Ω or 4Ω is specified using nominal impedance.
If you measure the voice coil with a digital multimeter, the resistance reading may not be exactly 2.0Ω or 4.0Ω.
That does not necessarily mean something is wrong with the subwoofer.
A multimeter measures DC resistance, while the subwoofer’s rated impedance describes its nominal AC impedance during operation.
Therefore, a resistance measurement somewhat below the nominal impedance rating can be normal.
Both Voice Coils of a DVC Subwoofer Should Be Used
A Dual Voice Coil subwoofer is designed to operate with both voice coils connected.
Do not simply leave one voice coil disconnected as a shortcut for achieving a desired impedance.
Doing so can change the subwoofer’s operating characteristics and power handling.
Use an appropriate series or parallel configuration involving both coils.
Use Matching Subwoofers
When multiple subwoofers share an amplifier, use matching models whenever possible.
Ideally they should have the same:
Model
Voice-coil configuration
Voice-coil impedance
RMS rating
Mixing different subwoofers can create unequal power distribution and unpredictable system behavior.
Always Verify Wiring Before Connecting the Amplifier
Before applying power to a newly wired subwoofer system:
1. Verify the exact subwoofer model.
2. Confirm whether it is SVC or DVC.
3. Confirm the impedance of each voice coil.
4. Verify the wiring configuration.
5. Calculate the expected final impedance.
6. Verify that the amplifier supports that impedance.
7. Verify the amplifier’s RMS output at that impedance.
8. Confirm that the power level is appropriate for the subwoofer system.
If possible, use a digital multimeter to check the completed speaker wiring before connecting it to the amplifier.
Remember that the measured DC resistance will normally differ somewhat from the system’s nominal impedance.
Quick Reference
One DVC 4Ω Subwoofer
Parallel → 2Ω
Series → 8Ω
One DVC 2Ω Subwoofer
Parallel → 1Ω
Series → 4Ω
Two DVC 4Ω Subwoofers
Common parallel configuration → 1Ω
Two DVC 2Ω Subwoofers
Common series/parallel configuration → 2Ω
These are common configurations, not a complete list of every possible wiring arrangement.
What Information Is Needed Before Recommending a Wiring Configuration?
Before recommending how a customer’s subwoofers should be wired, determine:
Exact subwoofer model
Number of subwoofers
SVC or DVC
Voice-coil impedance
RMS rating per subwoofer
Exact amplifier model
Amplifier RMS output by impedance
Amplifier minimum stable impedance
If any of these critical specifications are unknown, they should be determined before recommending a final wiring configuration.
The Simple Rule
The best wiring configuration isn’t necessarily the one that creates the lowest impedance.
It is the configuration that provides:
A safe impedance for the amplifier
Appropriate RMS power for the subwoofers
A system the vehicle’s electrical system can properly support
All three should be considered when designing a car audio system.
Need Help Wiring Your Massive Audio Subwoofers?
If you need help determining the correct wiring configuration, provide:
Subwoofer model
Number of subwoofers
Amplifier model
Vehicle year / make / model / engine
Massive Audio can then help determine the appropriate wiring configuration and system requirements.
Important Installation Note
This guide is intended to provide general educational information about subwoofer wiring.
Always verify the specifications for the exact amplifier and subwoofer being installed before making wiring connections.
Incorrect wiring or operating an amplifier below its minimum rated impedance can result in excessive heat, protection mode, equipment damage or failure.
For complex or high-power systems, Massive Audio recommends having the installation evaluated by an experienced professional car-audio installer.