How to Match Car Amplifier With Subwoofer?


Matching your car amplifier with your subwoofer is crucial to avoid any damage to the car audio system.

You will need to match these two items to get a good balance of sound, and you need to be sure that you get the right power to the sub for the sound quality you need. But how to match an amplifier to the car subwoofer? Let’s find out.

Generally, a car amplifier should have RMS wattage equal to or slightly higher than the total RMS wattage of all connected subwoofers at the same impedance. However, matching an amplifier of a different impedance than a subwoofer is more complicated, and it depends on the exact wiring type.

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Tip: If you have been struggling to know which kind of amplifier and subwoofer pairing you need for optimal sound, the best is to search through the monoblock amplifiers from either Rockford Fosgate or Memphis Audio and match their parameters with the subwoofers you have.

Both types can power even the strongest subwoofer systems, and you will not be disappointed with them, but if you look for a more affordable alternative, check out the wide selection of Skar amplifiers on Amazon.

If you are ready to learn more about the process of matching your car amplifier with your subwoofer, read on!

How Do I Know What Size Amp I Need?

The general rule of thumb for choosing an amp is to make sure that your amp will deliver continuous power (RMS Wattage) that is at least equal to the subwoofer’s RMS Wattage if both amplifier and subwoofer have the same impedance (Ohm).

You will also need to make sure that your subwoofer will not overpower the amplifier. This is because subs need a lot of power, and you will need to balance the power demands of the two items in your overall system.

You need to be sure that the power will be divided evenly between the two items so that you will get excellent sound quality and so that you will not damage the amp or the sub.

Skar Audio RP-1500.1D Monoblock Class D MOSFET Amplifier with Remote Subwoofer Level Control, 1500W

For example, if you have a 300W RMS 4 Ohm subwoofer and connect it to the 100W RMS 4 Ohm amplifier, you risk the amp will quickly enter the protect mode, and in the worst case, this amplifier will get damaged.

This s because the amount of current the subwoofer will ask for is too much for the amplifier, so its internal components will start to overheat in no time.

Do More Watts Mean More Bass?

More watts do not automatically mean more bass. Watts can denote a more powerful subwoofer, but your sub might not be able to perform to this level of wattage if you do not have the suitable space or the other supporting features and factors required to handle this wattage.

A huge sub will need lots of watts, but a huge sub is not always the right choice for your needs.

You will typically not have the air space to allow a huge subwoofer to work effectively in smaller cars.

This means that you will need to be sure that you are not so focused on watts that you are not considering the factors that make sound high-quality.

A smaller sub that draws less current and also is cheaper, can sound much better than a big and greedy sub that does not have enough airspace for the optimal work.

More watts can lead to more vibration as well, which can make the sound inside your car very poor. You will also need to consider that your car’s battery must tolerate the draw that a large sub pulling many watts will need.

You might be surprised about how few watts are really needed to operate a high-quality smaller sub that is ideally suited for your car sound system.

Remember that air space is critical for sound quality and often has more to do with sound clarity and bass generation than watts.

If your sound system does not consider the air space needed to resonate bass and lower-tone sounds, you will just get not much more than lots of noise, vibrations, and rattling all over the place, instead of the quality sound you were hoping for.

Can an Amp Have More Watts Than a Sub?

Your amp can have more watts than you sub so long as you use the proper impedance considerations.

The connections between the two parts of your sound system need to be done correctly, but if they are, there is no reason that your sound system cannot tolerate a small mismatch in the two items. Ideally, your amp will have more room for more headroom.

Amps can overheat and turn themselves off if they are getting too much in the way of wattage. You must also remember that your sub will be quieter when the amp does not produce the right amount of power.

You will need these two items to balance to get the most out of your sound system overall. The balance of your amp with the subwoofer is key to getting balanced power distribution and excellent sound quality.

There is a lot that many people could say about how to balance these items in a general sense ideally, but the needs of each of the products that comprise your system can determine the ideal amounts of power that each item will draw.

You will not be able to set up your system in an ideal way without the right balance of power for the needs of each product, and each scenario has to be calculated individually.

For example, if you have four subwoofers Kicker CVX12, they may be connected differently depending on their impedance, either 2 ohm or 4 ohms.

In either case, their total RMS Wattage will be 3,000W (4x750W), but because of their different impedance, you have to choose completely different amplifiers, but their total wattage should be as close as possible to the 3000W RMS at the adequate impedance.

What Happens if You Underpower the Car Subwoofer?

Underpowering a sub creates different risks than overpowering it. This is a good rule of thumb for your whole sound system.

You will always want to aim for powering things in a conservative way compared to overpowering things and ruining critical components of your car sound system.

In many cases, your sub can handle much more power than your amp, so you will find that your amp will probably limit your system more than your sub, and you may start hearing its clipping noise.

Your subs will not sound as clear or loud when they do not get enough power, but the weak amp can often be your trouble spot when handling power, and in some cases, it can stop working whatsoever, putting itself into protection mode.

Can You Run 2 Subwoofers on a Monoblock Amplifier?

You can wire multiple subs together, but make sure they all have the same type and impedance.

If not, your power will be unevenly distributed among them, resulting in some getting overpowering while others are underpowered. This is especially dangerous if your subwoofers have different numbers of voice coils or different impedance.

You might want to run different subwoofers in the car simultaneously if you’re looking for even volume distribution, however, in this case, each woofer needs to have its own amplifier.

A monoblock amp offers 1 channel to work with, and it cannot be bridged. You can usually convert this setup to allow for two or more subs, however. 

The answer to using this kind of amp with more than one sub is all in the wiring. You will likely need help to set up this kind of wiring, and to show you the main connection alternatives, below is the overview showing created based on the number of subwoofers with their voice coil type and their impedance.

Number of SubwoofersVoice Coil TypeSubwoofer’s ImpedanceWiring Diagram
1Single (SVC)2 ohms2 ohms
1Single (SVC)4 ohms4 ohms
1Double (DVC)2 ohms1 ohm or 4 ohms
1Double (DVC)4 ohms2 ohms
2Single (SVC)2 ohms1 ohm or 4 ohms
2Single (SVC)4 ohms2 ohms
2Double (DVC)2 ohms2 ohms
2Double (DVC)4 ohms1 ohm or 4 ohms
3Single (SVC)2 ohms6 ohms
3Double (DVC)4 ohms1.3 ohms
3Single (SVC)2 ohms1.3 ohms or 3 ohms
3Double (DVC)4 ohms2.7 ohms or 6 ohms
4Single (SVC)2 ohms2 ohms
4Single (SVC)4 ohms1 ohm or 4 ohms
4Double (DVC)2 ohms1 ohm or 4 ohms
4Double (DVC)4 ohms2 ohms
Matching Car Amplifier with Subwoofer – Wiring Diagrams (source – Crutchfield)

To make selection easier, I added a link to the corresponding amplifier in each scenario, based on the 200W RMS subwoofer example.

Number of SubwoofersVoice Coil TypeSubwoofer’s ImpedanceMatching Amplifier
1Single (SVC)2 ohmsSkar RP-350.1D
1Single (SVC)4 ohmsSkar SK-M5001D
1Double (DVC)2 ohms Skar RP-350.1D (1 ohm) or
Skar SK-M5001D (4 ohms)
1Double (DVC)4 ohmsSkar RP-350.1D
2Single (SVC)2 ohmsSkar RP-350.1D (1 ohm) or
Skar RP-800.1D (4 ohms)
2Single (SVC)4 ohmsSkar SK-M5001D
2Double (DVC)2 ohmsSkar SK-M5001D
2Double (DVC)4 ohmsSkar RP-350.1D (1 ohm) or
Skar RP-800.1D (4 ohms)
3Single (SVC)2 ohmsSkar SKV2-2500.1D
3Double (DVC)4 ohmsSkar RP-800.1D
3Single (SVC)2 ohmsSkar RP-800.1D (1.3 ohms) or
Skar RP-800.1D (3 ohms)
3Double (DVC)4 ohmsSkar RP-800.1D (2.7 ohms) or
SKV2-2500.1D (6 ohms)
4Single (SVC)2 ohmsSkar RP-1200.1D
4Single (SVC)4 ohmsSkar RP-800.1D (1 ohm) or
SKV2-2500.1D (4 ohms)
4Double (DVC)2 ohmsSkar RP-800.1D (1 ohm) or
SKV2-2500.1D (4 ohms)
4Double (DVC)4 ohmsSkar RP-1200.1D
Matching Car Amplifier with 200W RMS Subwoofer

As you can see, there are many options, and choosing the right amplifier depends on the subwoofer and its connection type.

What if My Amp Is Too Powerful for My Sub?

Amps that are way too powerful for a sub can actually ruin the sub when run at high volume.

You need to consider the comparison between the power of the amp and the sub as one of the key elements to allow your system to work properly each day.

To get the optimal power from the amplifier, multiply the number of subs you have by the RMS rating of each, and you will get their total RMS rating. You want to make sure the amp you choose will supply at least the same power that is your subs total RMS rating.

For example, if you have two woofers with the 200W RMS each and want to connect them to a two-channel amplifier, make sure to buy an amp that can deliver at least a total of 400W RMS.

Car amplifiers can deliver much more power than many can realize, but to do that, they need a large amount of current from the car battery.

Picking the right amp, therefore, is necessary to care for your sub and your car’s battery. You do not want to go climb in your car to head out to work and find that your battery is dead.

Subs are just as expensive as amps, if not more so, so in most cases protecting your sub is critical to being spared from having to replace your sub each time you have the music turned up.

Amps that are too powerful for a sub are also too powerful for the speakers in your system.

This can be the other weak link to your car audio system, and many people forget about how much blown speakers can ruin a sound system as well.

When you overpower your sub, you will find that the problems with your sound system balance can sneak up on you.

You will potentially not notice that one of your speakers has been blown out, and this early sign of problems can be too small of a warning to spare your sub from damage later.

You need to be sure that you think about the full extent of what you will be expecting from your system and make sure that your amp and your sub are both up to that challenge.

What Happens if My Amp Has More Watts Than My Speakers?

As mentioned before, you need to think about what your subwoofer can handle when picking an amplifier.

The question is not entirely about the pairing between your amp and your sub, but it has rather more to do with the sound quality of your entire car audio system.

At the end of the day, you can pick any amp and any sub, but your speakers need to perform at the same level as the rest of the sound system that you have chosen for your needs.

When your amp offers many more watts than what your woofer can handle, you might end up damaging the sub. On the other side of the equation, if you do not supply your woofer with enough power, it will not sound great, and you will risk damaging the amplifier.

You need to be sure that you look at the watts that your sub can handle and then ensure that you are supplying it with the right amount of power.

Conclusion

Matching your car’s amplifier with its subwoofer is not too difficult, but it is something that not everyone is comfortable with.

To make the right choice, you need to consider many different features and factors when picking the components of your sound system for the best results.

You will need to ensure that your amp and your sub are balanced as far as power and impedance.

The entirety of your sound system can be impacted by the power draw needs required to fuel it. For example, if you have a smaller car, your sub or your amp might not perform in the way that you wish due to a lack of battery power.

Make sure that you think about all of the parts of your sound system when you are planning the power needs for each one.

A well-balanced sound system is really enjoyable to have in your car, and the power that is being supplied to each part of your sound system can significantly impact the quality of the sound that your system produces.

Martin

Welcome to ImproveCarAudio! I am Martin, and I love to write about everything related to car sound systems. I strive to provide the most accurate and helpful information about car audio through extensive research, as well as my experience with car audio installations.

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