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How to Make Subwoofers Louder Outside the Car?

If your subwoofers are not producing the desired volume, it may be because they are most are not optimized for playing outside the car.

Subwoofers produce low frequencies and require more power than other speakers to function correctly. But, how can you make subwoofers louder outside the car? Let’s find out.

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In general, to make the subwoofer louder outside the car, you have to make sure that your subwoofer is getting as much power as it can handle and if this is still not enough, add another amplifier. It is also important to add at least a second woofer and install it in the ported enclosure with the speaker facing the rear window in the car.

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Tip: You don’t want to get a ticket for excessive noise, do you?

Before making any changes and installing a monster subwoofer like Skar Audio Dual 12″, it’s important that you check with your state or territory if the sound system in your car is considered street-legal and whether you will be breaking any laws. Unless you make your sound system for the competition, there are different regulations, and I have summarized them in this article.

Some time ago, I highlighted the risks of having the sound system in the car too loud, so check it out if you want to know more.

Subwoofers were initially designed as an internal component of a car stereo, but if your system is not reaching its full potential, here’s what you need to do to optimize them for outdoor use.

What Makes the Car Subwoofer Loud?

To make subwoofers loud outside of the car, you need to understand how they work inside.

First, subwoofers are designed to reproduce all frequencies up to 150 Hz. Some models can go as low as 20 Hz, but that depends mainly on their size. So they’ll also reproduce bass guitar or electronic instruments that play at those frequencies.

One thing to remember, if your subwoofer can’t reach these lowest frequencies, it won’t sound loud and deep enough at a larger distance.


Sensitivity is measured at 1W @ 1m, but that’s not the only thing you should look for.

Sensitivity is also directly related to the maximum SPL, and that depends on the amplifier’s power and how loud it can go without starting clipping.

Usually, SPL alone tells more about loudness than sensitivity. For example, a subwoofer with a higher maximum SPL will play at reference volume one yard away from your car than a subwoofer with a lower SPL.

Also, note that loudness varies by sensitivity, so you will notice that a subwoofer with a sensitivity of 98dB will be louder than the other one with only 88dB at the same frequency.

Subwoofer Size

One thing that matters the most when it comes to the bass depth is the subwoofer size.

Larger subs can play loud and deep enough for your needs, but they may be too large for your trunk, depending on the car type you have. In short, bigger subs usually play deeper than smaller ones.

When installing the subwoofer, you should place it in an open area, where it can fill the bass with minimal interference from obstacles around the speaker or internal car’s body frame.

This is why it is important to place the woofer in the position so the cone can face the rear door rather than the back seats.

make subwoofer louder outside

The most common mistake for many people is buying a cheap but large woofer instead of a smaller but good one. If you buy a budget woofer, it may play low frequencies as expected, but it won’t play as loud or clean as an expensive subwoofer would.

Type of the Enclosure

Another critical to the loudness is the type of enclosure you want to use. Although sealed enclosures are amazing for sound quality, they are not loud as ported ones.

The loudest subwoofers use ports for additional bass reflex, which maximizes their loudness thanks to the unrestricted airflow.

This can be easily seen when you look at the subwoofers, and if you see an open channel (port), that means the sub will play deep bass.

The only disadvantage of ported enclosures is that they are not very accurate in sound quality, but this won’t be a problem if you look just for loudness.

Power Handling Capability

When choosing the subwoofer, do not forget about power handling. The loud subwoofer is the one that can handle more power due to the larger magnet and huge voice coils that can dissipate high amounts of energy.

But do not look just at power as a single parameter to consider. For example, a powerful 10″ subwoofer with low sensitivity will not be louder than a less powerful 15″ with a sensitivity larger by 3dB.

When looking at the wattage, remember always to check the real continuous power RMS, rather than a peak wattage, which can be twice as high.

Producers use this trick to mislead buyers by saying that a specific subwoofer has 2,000W, but in reality, this is a peak volume, while the real power may be 800W RMS.

How to Place a Subwoofer for the Best Sound Effects?

Placing the sub in the wrong position can minimize your audio experience, and the produced bass can sound muffled. Therefore, you need to get the best position for subwoofers in the car.

If you drive a large truck or SUV, you have plenty of room to play with the subwoofer, but there are some limitations for cars with smaller trunks.

The best position for any car subwoofer in the trunk is when there is enough space in front of the cone and next to the port to allow air to flow freely.

Unrestricted airflow will not compromise a bass reflex effect, and you will be able to hear the sounds from a large distance.

Ideally, if the enclosure is lying flat with cones facing the top side or the car’s rear side. Try to avoid placing subwoofers which speakers are facing rear seats. 

Should I Add Another Car Subwoofer?

If you have enough room in the trunk, you can install a large box with two or more woofers for better performance.

Doing so will create an extra loudness effect, and you do not have to go for too large speakers because two good 10″ subwoofers will be louder than one 15″. They may not play at the deepest frequencies below 20Hz, but they will be louder.

For example, Skar Audio Dual 10″ with a 2,000W RMS tuned at 32Hz can put your trunk apart. If you have a larger trunk, try a Skar Audio Dual 12″ that works with a 2,500W RMS, and this is a true monster.

Skar Audio Dual 12" 5000W Loaded EVL Series Vented Subwoofer Enclosure | EVL-2X12D4

The only thing regarding the 12″, you need to power it with something like Hifonics BXX4000.1D Brutus for the best effect.

But with the above combination and lowered windows, try not to turn the volume over a half.

How Much Power Do My Subwoofers Need?

The power you want to supply for your subs depends on their RMS wattage. Therefore, the RMS wattage is the first thing you want to look at when matching the suitable amplifier.

The amplifier’s power should be between 1x to 1.5x RMS power of the subwoofer for the best effect. The amplifier has to be more powerful than a subwoofer because this power reserve reduces or entirely removes the risk of clipping at the highest volumes.

If your subwoofers have a 2,500W RMS like the Skar Audio Dual 12″, the amplifier should be 3,000 and 4,000W RMS.

Remember that also the impedance of both the subwoofer and the amplifier must match. If you have a sub supporting 1ohm, the amplifier also has to work with 1 ohm.

Also, always buy the amplifier to match the subwoofer and not the subwoofer to match the amplifier.

How Should I Tune the Amplifier for the Loudness?

Installing a subwoofer and amp can make your car sound more dynamic, but just installing these components isn’t enough.

For the best results, you have to tune the settings in the amplifier. If you don’t bother with further adjustment though, there will be distortion or muddy bass sounds, which in some cases is worse than not having any sub at all, so it’s important to know how this works.

Amplifiers have several filters that have to be carefully tuned for the best effect. The most important is a low pass filter (LPF) and a high pass filter (HPF) which cuts out from the sub all the frequencies you do not want to work with.

If you want to tune the amp by yourself, below are a few basic steps so you can enjoy clear and loud bass:

  1. Turn the subwoofer amp gain down.
  2. Turn the low-pass filter up.
  3. Turn the bass boost off.
  4. Turn the head unit on and make sure all equalizer settings are set to zero.
  5. Play dynamic music, but do not turn on the volume over 50%.
  6. Slowly turn up the gain on the amplifier until you hear a clipping noise.
  7. Back off the gain until the distortion goes away, it usually disappears with a reduction by -6dB.
  8. Lower the low-pass filter until you hear only bass without any mid frequencies. In some cases, you may need to reduce it by over a half.

If you are not happy with the result and your amplifier has a bass boost, turn the bass boost on and repeat the above tuning process.

It’s important to note that if your audio system has any other amps, each one has to be tuned separately.

Do I Need to Soundproof the Car for a Better Bass?

Subwoofers create enormous vibrations from the bass, and they have to be installed in a stable way that you do not hear the whole car shaking.

While some vehicles have basic sound deadening, mainly in the floor area, which slightly reduces noise from the exhaust and the temperature, this is not enough for the bass in the car.

Having applied sound deadening that covers the entire floor and also seals any openings in the doors will significantly improve the performance of your car audio system, especially bass distribution within and outside the cabin.

The sound deadening panels will not only make the entire cabin more sealed, but the extra rubber on the metal panels will stop the car from rattling.

For me, the best for the trunk is thick sound deadening foam Siless Liner 157. You can apply it on the entire car floor, roof, and side panels.

Because of its thickness, it creates an excellent sound barrier, and it cancels all sounds coming from the outside. In effect, you hear only crystal clear music and feel deep kicks from the subwoofer.


Making a car subwoofer loud outside is not difficult, but there are a few key points you have to remember:

  • Number of the subwoofers
  • Power from the amplifier
  • Enclosure type
  • Proper tuning of the amp’s settings
  • Sound deadening

With all the above, if applied correctly, you will have to be careful and not play too loud music in public.

Such a system is loud enough not only for your personal use but also can annoy other drivers on the road and the neighbors.

If you are looking for loud subwoofers outside, you should definitely consider Skar Audio Dual 12″ from the top line EVL or its smaller brother Skar Audio Dual 10″

Both are extremely loud, and you will not be disappointed by the noise outside your car.