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Wiring subwoofers — what's all this about ohms?

How wiring affects your sub's output

Kicker 44DCWC102

Kicker DCWC102 ported enclosure with dual 10" CompC subwoofers

Confusion concerning watts, amps, and ohms has been around for as long as people have been putting subwoofers in cars. Watts and ohms are entangled in a series of mathematical formulas that link them intimately together such that when one of them undergoes a change in value, the other often does too.

Briefly, here's how it works

Amplifiers provide the electrical pressure in a circuit; ohms measure the resistance, or load, against that pressure; and watts measure how much power is released as work. So, using one of those math formulas, an amplifier that provides 100 watts of power through a 4-ohm speaker, will produce 200 watts through a 2-ohm speaker, because it's easier to push that reduced load.

Voice coil makes sound — amplifier pushes it

At the heart of every speaker and sub is a voice coil. This is the device that puts up the electrical resistance and performs the work. (The amplifier provides the power.) The resisting property of a coil is called its impedance and is measured in ohms. The lower a speaker's impedance, the easier it is for an amp to supply power to it. Problems arise when the amp's output meets very little resistance (low impedance) and it tries to put out more power than it was designed to produce. This leads to the amplifier overheating and then, hopefully, shutting down to protect itself from burning up.

You don't want the amp to over-do it

So the capability of an amplifier has to be considered before applying a load to it (hooking up a speaker). The manufacturer's specifications indicate an amp's minimum impedance requirements. Almost all amps can drive a 4-ohm load. Most amps can work with 2-ohm loads on each channel, but not when the channels are bridged together. Some amps can drive a load as low as one ohm.

Pioneer GM-A3702

The two channels of this Pioneer GM-A3702 amp can be bridged by wiring the subas indicated

Wiring options change a sub's impedance

To add to the confusion, in multiple-sub systems, the total impedance depends on how the subs and their voice coils are wired together — in parallel or in series. Parallel wiring means that the connection ends of each device are connected to the same things — plus to plus, and minus to minus. Series wiring means that the devices are wired one after the other — a plus of one to a minus of another.

When speakers or voice coils are wired in series, you add their impedances together to find their total impedance. Two 4-ohm speakers wired in series have a total impedance of 8 ohms. When speakers or coils are wired in parallel, however, the formula for their total impedance is more complicated. When the impedances of all the devices are the same, their total impedance, when wired in parallel, is that impedance value divided by the number of devices. For example: four 4-ohm speakers wired in parallel have a total impedance of 1 ohm.

Rockford Fosgate T1D212 sub

This Rockford Fosgate DVC 2-ohm sub has a built-in jumper so you can choose whether it has a 1-ohm or a 4-ohm total impedance

Dual Voice Coils give you even more wiring options

Subwoofer manufacturers make subs with dual voice coils (DVC) to take advantage of this difference in wiring schemes, so the user has more freedom of system design. A DVC 4-ohm sub can be wired into a system as a 2-ohm or as an 8-ohm load. A DVC 2-ohm sub can have a total impedance of 1 ohm or 4 ohms.

An example using 4 subs:

If I wanted 4 subs in a system, I might consider using 4 DVC 2-ohm subs, each with their voice coils wired in parallel to make them each 1 ohm subs, and then wire the 4 of them in series so my amplifier could drive them as a single 4-ohm load. Or, I could wire the voice coils in series, making them all 4-ohm subs, and then wire the subs in parallel so the amp would see the total load as one ohm. It would depend on my particular amplifier — which load it would do the best with.

Match power to power — use RMS only

To make subwoofers sound their best, they should be powered by an amp whose RMS output rating comes close to or even slightly exceeds the total of all the subs' top RMS ratings. If you want to run three subs whose RMS ratings are 300 watts each, you'll need about 900 watts RMS of power to run them.

Underpowered subs won't sound good or play very loud. Then, if you were to turn up the input to compensate, the amp could end up sending out clipped or distorted signals that could damage the subs. It's okay to overpower your subs a little bit, as long as the signal's distortion-free, because they're made to withstand occasional peaks well beyond their normal RMS rating.

What's right for you?

The sub and amp you need depends on what you want to hear. If you plan on listening to music at moderate volume levels or have a smaller car, a subwoofer with a lower power handling rating, say 100 to 250 watts, and a matching amp is a good combo.

The ultimate goal is to have the amp send its full power to subs that can handle it. The object of using different wiring options to optimize the impedance is to get the most power out of the particular amp and subs you have at hand. This also happens to be the most efficient way of running an amp & sub system. For more wiring specifics, check out our subwoofer wiring diagrams.

If you want to get right into choosing a subwoofer, take a look at our top-rated and best-selling subs.

  • Aj from Tallassee

    Posted on 9/17/2022

    I have a star audio ZVX 12 d2 with a star audio rp.2000 watt amplifier whats the best way to wire this combo

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/17/2022

    AJ, If your gear is actually Skar Audio gear, then the safest way to wire them together is like this
  • Jules Bruchez Jr from Saint Martinville

    Posted on 8/18/2022

    I am going to run one 10" Kicker Q Class subwoofer rated for 700rms. My amp at 2 ohms can push 750 rms but it can also put out 100 rms at 1 ohm without electrical interference in the car. I would not push the sun past say 800 watts but the sun will be inside of a sealed box. What would be a better choice for ohm load?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/18/2022

    Jules, Those model Kicker subs come in DVC 4-ohm and DVC 2-ohm models. Which one you get will determine what impedance it can be wired as. So, without knowing precisely what amp and sub you're referring to, we can't help you with advice. If you want a question answered about a system, you must identify the gear by brand names and model numbers so we can get the right information to you.
  • Andy from Tucson

    Posted on 7/11/2022

    Can I wire a 12w7 with a single voice coil 3ohm load with a 12w7 with a dual voice coil with each coil at 1.5ohms to a 1ohm stable 1000watt amp and will each speaker get even power?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/14/2022

    Andy, This is a rare case where you can wire different subs together safely - these have the same power and sensitivity ratings, so when wired together correctly, they will share their power evenly. You can wire the DVC sub's coils together in series, creating a 3-ohm sub, and then wire the two subs together in parallel, making a 1.5-ohm load at the amp.
  • David Dinh from Snellville

    Posted on 7/8/2022

    Currently trying to run 2 12tw3 d4 to a Rockford r5001xd that's rated at 500w at 2ohms. I believe my amp is underpowered but how should I wire the 2 12". Series or parallel to get the best and most out of them?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/8/2022

    David, Two DVC 4-ohm subs can only get wired together to form a one-ohm load, a 4-ohm load, or a 16-ohm load. That amplifier can't handle a 1-ohm load, so the best you can do with that gear is to wire the subs as a 4-ohm load. That way, the amp would put out a total of 300 watts RMS to the two subs. If that isn't loud enough for you, you could get a more powerful amp, say one that could put out up to 800 watts RMS at 1-ohm or 4-ohms.
  • Westley from Festus.

    Posted on 6/26/2022

    Could I run 4 ct sounds tropo 8 400 watt rms in a sealed box and push them properly with a Jl audio hd750 amp if wired together at 2ohm?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 6/27/2022

    Westly, Those four DVC 2-ohm subs should get wired to that amp like this. They can't be wired as a 2-ohm load - but that won't matter, because the amplifier puts out the same wattage at 4-ohms as it does at 2-ohms.
  • Bill from Rohnert Park

    Posted on 5/27/2022

    I have (2) 10" JL Audio W6v3 subs with dual 4 ohm voice coils. I am using a JL Audio VX1000/1i mono amp. This is going in a Chevelle where I will be playing reggae/hip hop/ 80's rock. I enjoy loud bass, what wiring set up should I go with?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/27/2022

    Bill, The only safe way to wire those subs to that amp is like this.
  • Carlos De Los Reyes from eagle pass

    Posted on 5/3/2022

    I have pioneer tw-w2502d4 and i have a pioneer gm-a5602. I don't think i am connecting correctly. Do i need a bigger amp? if i do, do i go by 1000 watts rmc at 2 of 4 ohms?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/3/2022

    Carlos, That DVC 4-ohm sub can only be wired as a 2-ohm or an 8-ohm load. The only safe way to wire it to that amp is like this - so the 800 watts RMS rated sub will receive up to 300 watts RMS from the bridged 2-channel amplifier. If that's not loud enough for you, you should get a larger subwoofer amplifier.
  • Christian Wilson from Louisville

    Posted on 3/22/2022

    I have all skar audio equipment, 2 12 inch 1 ohm DC subs rms 1500 peak 3000, 0 gauge skar wiring kit. I have the option to swap subs for 2ohm instead of 1ohm subs, not sure which to pick yet. I have two amps (not sure which to use), one 1ohm rms 2500 peak 2900 watt amp, and one 1 ohm rms 3500 peak 4700 watt amp. Each amp has 2 channels. What amp/subs should i use and how should i wire the subs to the amp? Looking for low bass.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 3/23/2022

    Christian, This article should give you all the information necessary to match and wire subs and amps together. But maybe you'd be better off having a conversation with a real live human. Give us a call. A Crutchfield Advisor can help you choose the gear that'll work well together - not just the cheapest - and give you the right advice on how to wire them.
  • Mario Cardenas from Tucson

    Posted on 3/14/2022

    I have a Skar SDR-12 | 12" 1,200 WATT MAX POWER CAR SUBWOOFER not sure what ohm but I want to buy a new amp for it, I can either get an 800w rms 1200w max skar amp or a 1200w rms 1600w max amp , what should I get? I am looking to get the 1200w rms amp because I want to upgrade my sub in the future to a higher watt one but I also don't want to blow the one I have have right now.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 3/15/2022

    Mario, That sub comes in DVC 4-ohm and 2-ohm models, so I suggest you find out which you have before wiring an amp to it that could blow it up.

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