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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. 

  • Alejandro Hernandez from Houston Tx.

    Posted on 7/2/2022

    I have a JL audio 12tw3-d4 sub woofer only one. I want to know what amp would be good to push this sub woofer

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/3/2022

    Alejandro, That DVC 4-ohm, 400 watts RMS rated sub will work great with an amplifier that can put out up to 400 watts RMS at 2-ohms, like aSoundstream Reserve DPA1.2000D.
  • Dennis from New York

    Posted on 6/27/2022

    Hello .. I recently bought after market speakers .. a pair at 60 watts and another at 55 watts ..total of 4 speakers .. how much power should my amp and subwoofer be ? How many ohms as well ?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 6/28/2022

    Dennis, Nearly all aftermarket speakers have a nominal impedance of 4-ohms. Their RMS wattage ratings will tell you the maximum safe amount of amp power that will work for them. Give us a call, so an Advisor can help you pick out the perfect amplifier and sub for you and your system.
  • Tassos Vratolis from Athens

    Posted on 6/24/2022

    Hello from Athens Greece, I have this 5-ch amplifier, [Audison] and I am planning on buying this Sub from the same vendor, [Audison] I currently use the amplifier with these speakers [Audison] in the 55W 4 ohm configuration (leaves 185W for the SUB on the 5th channel). Is 185W (4ohm) inadequate power for the 400W RMS subwoofer, or would it be wiser to use another configuration on the amplifier, which is 4x50W RMS (4ohm) and 300W (2ohm) for the Sub. I prefer the 4ohm solution, but is 185W (4ohm) going to underpower the 400W RMS Sub?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 6/24/2022

    Tassos, Driving a 400W sub with 185W will present no problems, unless you want it louder - and then you'll need a larger amplifier.
  • John from Avondale

    Posted on 6/10/2022

    What subwoofer should I get for a planet Audio 1500 watt amp?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 6/13/2022

    John, Give us a call, so an Advisor can help you pick out a subwoofer that will work well with that amp and fit in your car.
  • Scott from Edwardsville

    Posted on 5/24/2022

    I'm looking for a 5 channel amp to run 4 speakers and 1 sub. All speakers will be around 100 watts RMS 4 ohms and am looking at the JL Audio 8" 8W3V3-4 SubWoofer. I don't see many amps that have 100 rms and the power needed to run that sub. What do you recommend? Thanks

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/25/2022

    Scott, Crutchfield offers six different 100W per front and rear channel 5-channel amps that have more than enough power for a 250W sub. Give us a call so an Advisor can help you pick out the perfect amp for your setup.
  • Janak from Rajkot

    Posted on 5/7/2022

    Sir i have come to know everything in this article of yours but have doubt that i don't currently have any subwoofer and amplifier but my idea is of two dvc 4 ohm subwoofer and i know about rms so I see in your diagram. I am confused which amplifier will be correct because in 4 channel amplifier 8 ohm of 8 ohm remains only while 4 of 8 ohm in mono and 2 channel becomes 4ohm of 8 ohm so please explain ohm in power and sound What is the difference between and which ohm amplifier will be correct for

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/7/2022

    Janak, Subwoofer voice coils are rated by their impedances, expressed in ohms - subwoofers have ohm ratings. Amplifiers react differently to different ohm impedance loads. Typically, for example, an amplifier that can put out 100 watts through a 4-ohm load will put out about 200 watts through a 2-ohm load. There are almost no benefits in using a multi-channel amp to drive a subwoofer system. Most 4-channel amps can't drive loads lower than 4 ohms when bridged, and don't have enough power to drive 2 subs. Mono, 1-channel subwoofer amplifiers are designed to work with a wider range of impedances, and have tone controls and filters specifically made to help reproduce bass.
  • Matt C from Houston

    Posted on 5/6/2022

    I have a single 12" Kicker Q Class L7 installed in a vented enclosure and was wondering which would sound the best (SQ & SPL), a Kicker KXA800.1 or a Kicker CXA1200.1? Or neither and go with a Rockford Fosgate amp? Any thoughts? Thanks

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/6/2022

    Matt, Those subs come in DVC 2-ohm and 4-ohm models. Which you have will affect which amp will work best. Give us a call so an Advisor can help you pick out the perfect amp for your setup.
  • Donald Norton from Mansfield

    Posted on 5/3/2022

    The article is good but flawed. It assumes all amps are a) efficient and b) make the rated power. Its not just ensuring you pick number x to go with sub x. If you buy a sub solely without researching if it can make the power you could have a sub setup that under performs then chase your tail to find out why. For instance you take your shiny 500watt amp out maybe its a class D and find it only has a 30amp fuse. If you are lucky to get 80% efficency you get 348-350watts. 30x14.4v x.80, worse if class a/b amp. Just saying do more research than reading numbers.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/4/2022

    Donald, Amplifier efficiency is not a factor when matching subs and amps together. That's only relevant when verifying an amp's output power. If you think an amplifier manufacturer's specs are deceptive or untrue, you should call out the specific offender and point it out for them to see and respond to. Crutchfield doesn't sell any amplifiers with deceptive manufacturer specifications - or we'll note when a discrepancy does occur.
  • Luis from Fresno

    Posted on 4/28/2022

    I bought two Rockford Fosgate Power T1S2-12 Power Series 12" T1 Slim Single 2-Ohm Subwoofer (600W RMS). What amp should I get to power them both?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 4/29/2022

    Luis, Two SVC 2-ohm subs rated for 600 watts RMS each, 1200W together, will work well with an amplifier that can put out 1200 watts RMS at 1-ohm, like a Soundstream Reserve RSM1.4000D, a Kicker 46CXA1200-1T, or a Rockford Fosgate R2-1200X1. Give us a call so an Advisor can help you get the right amp for you.
  • Lee from Bethesda

    Posted on 4/22/2022

    Hi. I have a hybrid car so limited on what I can use to the 30amp range. I really want to use a the Kicker TRTP 10" as the sensitivity is much better than the 8" model, but the RMS is 200-400. Would AudioControl's ACM 300.1 power this sub fine, or do I really need to find something that goes to 400 RMS or find a different sub that has a max RMS of 300?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 4/23/2022

    Lee, That amplifier should work well with that subwoofer in your vehicle.

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