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How to match subwoofers and amplifiers

Find the right amp for your sub or sub for your amp

How to match subs and amps

The secret to great bass is making sure your subwoofers and amp are evenly matched and will properly work together. And this article will help you figure out how to do just that — match amplifiers and subwoofers.

Getting the right sub for an amp, or the right amp for a sub, is like solving a puzzle. A subwoofer has impedance (measured in ohms) which represents the "load" an amplifier will sense on its output. An amplifier will put out different amounts of power (watts RMS) based on the impedance load it "sees."

Solving the puzzle

The amplifier's capabilities (X watts RMS into Y ohms) needs to match the subwoofer's specifications (Y ohms and can handle X watts RMS). Your goal is to get those two variables to match for both the amplifier and the subwoofer.

Below, we cover the important basics of power-matching, impedance, and planning for the number of subs you want, and we approach the situation from both sides of the system:

  • Part A: You have the subs, which amp should you get?
  • Part B: You have the amp, which subs should you get?
  • And also, Part C: You have neither amp nor sub, and want help deciding how to begin.

Start with either part you want, but A and B are both worth a read.


Part A — You have the subs, which amplifier should you get?

The subwoofers need to be the same

Multiple subs wired together must be the same coil type and impedance. If they’re not, the power won’t divide evenly between them, and some subs would probably be over-powered while others get under-powered. If you want to run different types of subs in a system, each type needs to have its own separate amp.

Step 1: How much power? Find out the “watts RMS” rating of the sub

Then, multiply the number of subs you have by the RMS rating of each, to get their total RMS rating. You want to make sure the amp you choose will supply no more than the sub system’s total RMS rating.

Step 2: What impedance? The results of combining coils and subs

Figure out the possible total impedance(s) that the subs can be wired together to form.
(SVC = single voice coil, 1 pair of terminals; DVC = dual voice coil, 2 pairs of terminals.)

  • 1 SVC 2-ohms can only have 2 ohms of impedance
  • 1 SVC 4-ohms can only have 4 ohms of impedance
  • 1 DVC 2-ohms can have 1 ohm or 4 ohms of impedance
  • 1 DVC 4-ohms can have 2 ohms or 8 ohms of impedance
  • 2 SVC 2-ohms can have 1 ohm or 4 ohms of impedance
  • 2 SVC 4-ohms can have 2 ohms or 8 ohms of impedance
  • 2 DVC 2-ohms can have 2 ohms or 8 ohms of impedance
  • 2 DVC 4-ohms can have 1 ohm or 4 ohms of impedance
  • 3 SVC 2-ohms can have 6 ohms of impedance
  • 3 SVC 4-ohms can have 1.3 ohms of impedance
  • 3 DVC 2-ohms can have 1.3 ohms or 3 ohms of impedance
  • 3 DVC 4-ohms can have 2.7 ohms or 6 ohms of impedance
  • 4 SVC 2-ohms can have 2 ohms or 8 ohms of impedance
  • 4 SVC 4-ohms can have 1 ohm or 4 ohms of impedance
  • 4 DVC 2-ohms can have 1 ohm or 4 ohms of impedance
  • 4 DVC 4-ohms can have 2 ohms or 8 ohms of impedance

For more combinations of subs and their impedances, see Subwoofer Wiring Diagrams.

Step 3: Pick an amp that can do both — X watts at Y ohms

Look for an amplifier that can put out power up to the RMS wattage  you’ve figured in Step 1, at an impedance load the subs can be wired to form, from Step 2.

Estimating amp power at the odd impedance values:

  • 8 ohms — figure on the amp putting out half the power it would at 4 ohms
  • 6 ohms — figure on the amp putting out three-quarters of the power it would at 4 ohms
  • 3 ohms — figure on the amp putting out the average of what it would at 2 ohms and at 4 ohms
  • 2.7 ohms — figure the same as for 3 ohms, and add a few watts
  • 1.3 ohms — use the 1-ohm spec and take away a few watts
Alpine S-W8D4

Example:
You have two Alpine S Series S-W8D4 8" subwoofers and you want the right amp for them.

They are DVC 4-ohm subs rated at 300 watts RMS each.

Two 300 watts RMS subs together need a maximum total of 600 watts RMS.

Using the chart in Step 2, 2 DVC 4-ohm subs can be wired together to form a 1-ohm, a 4-ohm, or a 16-ohm load.

The last is too high a load to be practical, so you’ll look for an amp that can put out up to 600 watts RMS into either a 4-ohm load, or a 1-ohm impedance load:

  • up to 600 watts RMS x 1 at 4 ohms, or
  • up to 600 watts RMS x 1 at 1 ohm

Among Crutchfield’s selection of amplifiers you’ll find:

Any one of these high-quality amplifiers would work well with those subs. It doesn’t matter which impedance an amp plays through — 600 watts RMS through a 4-ohm load produces the same volume as 600 watts RMS through a 1-ohm load.

JL Audio JD1000/1

JL Audio JD1000/1 subwoofer amplifier


Kicker KEY500.1

Kicker KEY500.1 subwoofer amplifier

Part B — You have the amplfier, which subs should you get?

Step 1: What can the amp do? Find the RMS ratings of the amp at different loads

Find the amp’s power, expressed in “watts RMS”, at 4 ohms, at 2 ohms, and, if it can, at 1 ohm. Pick the power you’d like to achieve. The load impedance (ohms) of that rating will be what you want your subs’ total impedance to be.

Step 2: How many subs do you want?

Divide the power you picked in Step 1 by the number of subs you want. This number is the target RMS rating for each of the subs you’ll choose. 

Step 3: What impedance does each sub need to be and how many voice coils?

Using the impedance you picked in Step 1 and the number of subs from Step 2, cross-reference the possible coil configurations that you can use: 

1-ohm 2-ohms 4-ohms
1 sub DVC 2-ohms SVC 2-ohms
DVC 4 ohms
SVC 4-ohms
DVC 2-ohms
2 subs SVC 2-ohms
DVC 4-ohms
SVC 4-ohms
DVC 2-ohms
SVC 2-ohms
DVC 4-ohms
3 subs (1.3 ohms)*
SVC 4-ohms
DVC 2-ohms
(3 or 2.7 ohms)*
DVC 2-ohms
DVC 4-ohms
(6 ohms)*
SVC 2-ohms
DVC 4-ohms
4 subs SVC 4-ohms
DVC 2-ohms
SVC 2-ohms
DVC 4 ohms
SVC 4-ohms
DVC 2-ohms
* Estimate amp power at the odd impedance values like in Part A, Step 3, above.

Step 4: Pick a sub that works for both — (SVC or DVC) X-ohms, Y watts RMS)

Look for subs that are rated at the wattage you figured in Step 2, and are configured as you found in Step 3. This might sound confusing, so let's walk through an example and it'll make sense.

Memphis Audio 16-SRX500D.1

Example:
You have a Memphis Audio SRX500D.1 amplifier and you want it to drive two subwoofers

The amp is capable of 350 watts RMS x 1 at 4 ohms and 500 watts RMS x 1 at 2 ohms.

Let’s say you choose to maximize the amp’s potential and want the system to put out 500 watts RMS. This means your subs have to be wired to form a total impedance of 2 ohms.

Two subs on a 500 watts RMS amp will want about 250 watts RMS each.
So you’ll look for subs each rated for 250 watts RMS or more.

Using the chart in Step 3, for two subwoofers, a final 2-ohm load can be achieved with either two SVC 4-ohm subs or two DVC 2-ohm subs.

So, you’ll look for two subs that are either SVC 4-ohms or DVC 2-ohms, rated for at least 250 watts RMS each:

  • 2 SVC 4-ohms, at least 250 watts RMS, or
  • 2 DVC 2-ohms, at least 250 watts RMS

Among Crutchfield’s selection of subwoofers you’ll find:

Kicker CompC 10"

Kicker CompC 10" component subwoofer

All these subwoofers will sound their best when amplified with the proper amount of power. Differences in size have more to do with tonal qualities and frequency response than with power performance. And optimizing performance is the point of matching subs and amps together.


Part C — You have neither amp nor sub, and want help deciding how to begin

Check out our other article, All About Subwoofers to learn the basics of how much bass you need and how to choose your subwoofers. 

And of course, if you have any questions, contact our expert advisors and they'll be happy to help you build your system. 

  • Stanislav from Svoge

    Posted on 10/19/2021

    Hello, first I would like to note that I am noob in the audio branch. I am looking to slightly improve the bass of my BMW. I have purchased two subwoofers with specs: 120W RMS/200W MAX ( I guess each one,as on both of them says 120W RMS), with an impedance of 2Ohms. I have also purchased an amplifier for them, with specs: Two channel amp with maximum exit output of 400W, 2x55W at 4Ohms, 2x85W at 2Ohms. I want to know if i had made a good choice, as once again saying I am total noob, just had a really good offer for them. If it will help, or matters - the subs are AI-Sonic BMW SW8, and the amp is Hertz HCP2. Looking forward for you reply.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 10/20/2021

    Stanislav, That gear will work best together with each of the subs wired to a separate output channel of the amp.
  • Omar P Rivera from Miami

    Posted on 10/18/2021

    I have 3 boss 10 inch subs four ohms what would be ideal to push these speakers and I have a five channel 3700 watt brigable amp can that be used with those speakers? I bought it with the box and wasn't sure if it could be used?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 10/19/2021

    Omar, Without knowing precisely what amp and subs 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.
  • Derek from Cambridge

    Posted on 10/14/2021

    I'm hoping you can help with my set up. Confused on how to tune the lc2i and amp. Sony XplodT XM-ZZR3301 and 2 12" kicker comp vr's wired/measured 4ohm. I have 1 pair of wires coming from the subs, how should I connect them to this amp? What should the lc2i be set to? (Amp looks like 6v max?) From there any insight on how to tune the amp? Thanks,

    Commenter image

    Buck Pomerantz from Crutchfield

    on 10/18/2021

    Derek, If there's only one pair of speaker wires for your sub, there's only one way to wire them to an amp: one wire to one output terminal and the other wire to the other terminal. But maybe I misunderstood your situation. For help tuning, see Tuning your subs. For the LC2i, use the peak light to maximize its output without distorting the signal.
  • Carter

    Posted on 10/11/2021

    Will two pioneer ts-as2500ls4 subs work with an Alpine S-A60M amp? If not then what amp would you suggest?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 10/12/2021

    Carter, That gear will work well together, wired like this.
  • Jesus Garcia from Belgrade, Mn

    Posted on 9/30/2021

    I am looking to buy 2 BOSS Elite BDVC12 1800W 4-ohm DVC what amp would go with those subs. Wondering if this one will be good Boss BE1600.2 1600W Elite Series Class-AB 2-Channel.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/30/2021

    Jesus, I don't know what you mean by "good" but that amp will safely power those subs with up to about two-thirds of their top RMS power rating. Never use maximum or peak power ratings - always use RMS amplifier specifications.
  • Neal from Martin

    Posted on 9/28/2021

    Hello, I currently have a Sony Xplod XM-GTX1852 1000W 2/1-Channel that has blown two subs in the past two year. One sub was a JLW0 and the other being a Kicker Comp 43C124. My amp only powers a single 12" sub. Each sub that blew was bridged at the amp when this occurred. I recently changed the sub to a Power Acoustik GW-124 which is dual voice coil. I have it bridged at the amp and the sub is wired in parallel. It hits loudly and I am satisfied with the sound but after about 10-15 min my amp goes into power recovery mode. I removed the sub and checked the resistance and both coil read at 4ohm so the sub isn't hurt and tells me the amp just got hot. What gives? First I was killing subs and now I'm killing the amp?? Any help is appreciated!

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/28/2021

    Neal, Your first sub blew because the amp sent the 150 watts RMS rated sub 500 watts. Your second sub blew because the 300 watts RMS rated sub was sent 500 watts. Your third sub is evidently wired as a 2-ohm load and the amp goes into protect mode because it can't handle that low an impedance load when bridged. The only way to safely wire that gear together is like this.
  • Jessica O from Glen Lyon

    Posted on 9/27/2021

    I have two of the following subs in a sealed box (each sub in its own separate enclosure), wired @ 4ohm with 12gauge speaker wire and a 1/0g 3000watt amp kit, also with 10 farad capacitor. Both of my subs are rattling, where did I go wrong? (I gave them a nice, easy break in period- only installed last september, 2 weeks ago the left side started rattling, then the right started not long after) Boss Phantoms 12" Woofer with DUAL 4 ohm Voice Coil 2300 Watts MAX 1150 Watts RMS Power Handling 84dB Sensitivity, 31 Hz Resonant Frequency ***Paired with: Boss PH5000 Amp 5000watt mono d class 2 ohms: 3500 watts x 1 chan. 1 ohm: 5000 watts x 1 chan. RMS power output: 1800 watts x 1 chan. @ 4 Ohms Variable low-pass filter (50-150 Hz, 12 dB/octave) Subsonic Filter (15-40 Hz, 12 dB/octave) Frequency response: 40-150 Hz

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/27/2021

    Jessic, Rattling occurs when there's loose hardware or blown speakers. Your two DVC 4-ohm 1150 watts RMS rated subs (2300W total) are probably wired together to form a one-ohm load, instead of a 4-ohm load, and the amp tried to send them 5000 watts which blew them to smithereens.
  • Ty from Palm Bay

    Posted on 9/14/2021

    I plan on getting 4 of the Skar Audio VD-10 D4 10-inch, dual 4-ohm, shallow mount. What amp would I need to get?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/15/2021

    Ty, Four DVC 4-ohm subs each rated for 500 watts RMS will work well with an amplifier that can put out up to 2000 watts RMS at 2-ohms, like a Kicker CXA1800.1T.
  • Noel from Carson

    Posted on 9/13/2021

    I have JBL GX628, GX528 on the doors, Rockford Fosgate P2D2-10, Alpine S-A55V. Would this setup work?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/13/2021

    Noel, That amplifier is a very good match for those speakers and sub.
  • alan blashka from charlotte, nc

    Posted on 9/11/2021

    i just read the subwoofer/amp article and unfortunately it is way over my head. i have an 'old school' receiver (kenwood kr-v8050) and the spec info provided shows 120W/channel minimum RMS @ 8 ohms. it also lists (surround) as front(75w+75w), center(75w) and rear(20w+20w). i used to have a yamaha surround sound setup with a subwoofer where the wiring went from the receiver to the subwoofer(it had a power on/off button, etc.) and then from the subwoofer to the R/L speakers. that also included rear/center speakers directly from the receiver. unfortunately the subwoofer died and was trashed a while ago and i need to purchase a new one. but i have no clue(no paperwork) what i need to know. what 'W' subwoofer can the receiver 'drive'. thank you.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/13/2021

    Alan, This article is about matching subs and amplifiers for car audio. In home theater applications, a receiver's subwoofer output is at line level, not amplified, and is used to drive a powered subwoofer. Give us a call, so an Advisor can help you pick the perfect subwoofer for your system.