How to Tune a Subwoofer Box at Perfect Frequency? Complete Guide

Tuning a subwoofer involves decoupling the subwoofer from the ground, finding the best frequency, and setting it on that frequency.

While tuning, we have to keep many things in mind because it is the most delicate procedure in the field of audio tunings.

The sound and bass quality of a subwoofer depends upon tens of things the size and tuning of the box and placement of the subwoofer are the most important factors.

I will completely guide you from selecting the right frequency for your box to tuning it on that.

Note:- All types of subwoofer boxes (sealed, ported, or free air subwoofer boxes, etc) have the same procedure of tuning.


There are three main types of boxes depending upon their designs.

Sealed Boxes

Those boxes which are tightly packed from every side and give no or less room to the subwoofer for breathing are called sealed boxes.

These boxes produce good sound and bass.

Ported Boxes

If you are fond of listening to deep or hard music like rock, you know the ported boxes. These boxes usually have two ports and produce more crunchy bass than sealed ones.

Ports are made to control the high power output of hard sound.

Free Air Subwoofer Boxes

The subwoofers which usually don’t need an enclosure are called free-air subwoofers and hence the subwoofer boxes which are not in the form of enclosures but just provide a standing or holding platform to the subwoofer are called free-air subwoofers.


Tuning the box is not time-wasting work. It is as important as your subwoofer’s wire selection.

Here are some things you will note after completing the tuning.

Enhanced Sound Quality

You will see that your subwoofer is sounding better than before. Tuning sets your subwoofer’s frequency at an excellent level. This allows the subwoofer to make sound and produce crunchy bass at its maximum potential.

For those music lovers who are worried about their subwoofer’s performance, I will recommend doing tuning once.

Increased Life Span

As we know if there is no bass in a subwoofer it means that the subwoofer is out of order or about to be.

Hence we measure the lifespan of our subwoofer according to its sound quality.

Tuning the box sets the subwoofer’s frequency at its maximum level. This makes the subwoofer rattle free and allows it to work properly which automatically increases the lifespan of the subwoofer.

Remember:- Those subwoofers who have tuned boxes, have more lifespan than untuned ones.

Increased Frequency

Many of the subwoofers normally produce sound at the frequency of 20Hz which is not too good.

Tuning can turn this 20Hz into 35Hz (which is the most accurate and compact frequency for producing the desired bass).

Frequency Spectrum


Tuning the box is not an unguided process. You have to keep many factors in your mind before doing this. Because this is an irreversible process, you have to do it carefully.


The most important thing which shouldn’t be neglected is the correct location and position of your subwoofer’s box.

Without this, you can’t tune it precisely.

There are some places in the room where you can listen to clear, same, and undistorted sounds. Please place your subwoofer at that place.

Area Of The Place

Suppose, you have a sealed subwoofer box and you are going to place it in an open area, it may rattle or produce unclear sound.

Select the placement area according to the type of your box. As free air boxes love open areas.

Frequency Settlement

An initial frequency at which a subwoofer or a speaker starts to produce bass is called a crossover or resonance frequency.

Ensure that your subwoofer should be set on its crossover frequency.

Note:- If you have an old subwoofer, you may not find this feature.

Physical Condition Of The Box

The outer condition also matters. If you have a damaged box, you may not tune it well.

In the case of a ported subwoofer, the damaged ports never let the box tune at the best frequency.

In case of a damaged box, you have to order a new one, make it by yourself, or louder your speaker manually.

In my point of view, the frequency of 34 or 35 Hz is best for tuning. If you increase the frequency to more than 40 Hz, it may produce distorted, unclear, and louder sounds than we require.

But in the case of ported boxes, the frequency may change according to the port or box size.

Pro Tip:- I will suggest you continue tuning your box at different frequencies until you find the best one.

I can’t give the exact answer to this statement. But the recommended one is 34 or 35 Hz.


I’m going to clear up your confusion about frequency selection.

Follow these points and configure the best frequency for your subwoofer’s box on your own.

Check Crossover Frequency

Crossover frequency which is also called resonance frequency is the one on which your subwoofer starts vibrating or produces bass.

Note down it. It may be written on your subwoofer or in the manual guidebook.

Size Of Box

The box size is another factor that impacts the frequency. First, you have to measure the size of your box and ports before further processing.

Remember:- Larger box size means a low frequency is required to produce excellent sound and vice versa.

Number Of Ports

Increase the number of ports, and increase the range of desired frequency.

Hence you have to count the number of ports first along with their size and area. It deeply impacts the frequency.

Not only the number of ports but also their shapes are also important.

Some of them are square shaped and some are circular. This factor plays an important role in the movement of air towards the box.

Windows Of Subwoofer

Many subwoofers have vents for passing air. The size, shape, and number of vents are also important.

You have to note down them too.

Remember:- The passing air + tuned frequency, both act simultaneously to improve the sound quality.


Gather these things before tuning.

  • Subwoofer Box
  • Isolation Pad or any Soft Material Ammeter
  • Sine Sweep Generator or Signal Generator Amplifier
  • Wooden Boards or poly-fill batting in case of ported box


So finally we are going to jump into the million-dollar question. Here you just need to follow these simple steps.

Step 1

Separate Sub From Ground

First of all, you need to decouple your sub from the ground. It reduces the rattling of the subwoofer and helps in better tuning.

Step 2

Place Subwoofer On Soft Material

Take a soft material like an isolation pad, or cushion. You can keep it on a bed or sofa so it can’t rattle.

Rattling heavily disturbs the frequency value and doesn’t let the subwoofer sound better. These soft materials will absorb the rattling and make your next steps easy to implement.

Step 3

Connect The Ammeter

For getting the resonant frequency you just have to connect your ammeter (AC and DC measurer) to the subwoofer and amplifier.

Remember:- The positive wire of the ammeter should be in the electric socket and the rest should be connected to the subwoofer and amplifier in a series fashion.

Now connect your amplifier’s input to the frequency signal generator or sine sweep generator.

Step 4
Find The Resonant Frequency

After all the connections are done. Now you just have to continue changing signals from the signal generator and keep an eye on the ammeter.

There will be a time when you see the maximum current value at the ammeter.

When you see this, stop there and immediately note the frequency value from the signal generator. This value will be the resonant frequency that we get at the maximum current value.

It means this is the frequency that allows maximum current to pass with less impedance.

Step 5

Set The Resonant Frequency

Now it’s time to set your subwoofer on the resonant frequency which we get at step number 4.


Suppose you have got a frequency at maximum current. But this was not what you were looking for.

Now you need to bring changes to your box shape.

In the case of a ported box, you need to increase or decrease the port size.


All the steps are the same, discussed above. But you just need to change the size of the ports by applying small wooden boards or poly-fill batting in them.

Hope, by doing this you will get your desired frequency soon.


The only thing you have to remember while tuning a sealed subwoofer box is that you have to give more power to it with a powerful amplifier than a ported one.

The tuning of a sealed box is a little bit tough job because they are tightly packed and don’t have ports for air traveling.


The procedure is almost the same. Take an ammeter, and connect it with a subwoofer and amplifier in a series fashion.

Connect the input of the amplifier to the signal generator.

Now vary the signals from the signal generator and note the maximum current from the ammeter.

The frequency from the signal generator you have got at that maximum current is the resonance frequency.

By using this resonance frequency as a gauge, you can calibrate your sub-box to the 30, 32, or 35 Hz frequency or whatever you want.


For calculating the desired frequency you have to consider many things like the volume of the box, air traveling, and resonance frequency of the subwoofer.

There is a formula by using it you can determine the almost exact frequency for your subwoofer at which it works well.



Fb= Frequency for the Box

A= Air Compliance

V= Volume Of The Box

Fs= Resonance Frequency

By filling in the required values in the formula, you can get the desired frequency.

Here is the Calculator, you can use for further calculations.


Tuning a subwoofer box is not an easy thing. Dealing with equipment and knowing the exact size of your box makes it tough.

I tried to keep things simple and easy. If you are not a technical person, I will suggest you consult an expert.

Many online calculators can help you to configure the best frequency. For that, you have to know the size, volume, and other required values of the box.

Many people get confused about the tuning procedure of sealed or ported boxes. Don’t confuse, they both have the same way to tune with a little bit of a difference which I have cleared above.


Is It Possible To Make a Subwoofer Box Louder?

Yes, it is possible. For this, you can use any soft material like Poly-fill batting inside the box around the ports.

This poly-fill batting can also be used in the sealed subwoofer. This gives a new look to the interior of the subwoofer.

When the subwoofer produces sounds, it reflects with the poly-fill batting and becomes louder.

Can The Tuned Frequency Be Low?

You can tune your sub at the lowest frequency. But honestly speaking, it is not good. It will not help to produce a high-quality sound and deep bass.

Both, too low or too high frequencies are not good. Just find out the best one which is in between them.

How To Tune A Car Subwoofer Box?

This is also the same as others. But one thing is different. That you need to measure the volume or area of that place in your car where you want to put this box.

Because in cars or trucks, mostly free-air subwoofers are used. Which required somehow an open space to work precisely.

So therefore you have to manage things accordingly.

Is RTA’s Software Good?

If you are not willing to use a signal generator hardware tool, you can use RTA’s software instead.

This will cost you less than the hardware and gives you more optimization options.