Subwoofer Phase 0 or 180 [The Complete Guide]

When setting up a subwoofer, one of the main questions people have is whether they should set the phase to 0 or 180.

Subwoofers are designed to reproduce low-frequency sounds, typically below and around 80 Hz. To do this effectively, they need to be able to move a lot of air. Depending on the positioning of your subwoofer, phase problems may appear and make the sound flabby if you don't take the necessary measures.

This is very easy to solve with a phase switch. Basically, the phase switch will apply a few milliseconds of delay to the subwoofer reproduction so that it is in sync with the main speakers.

In this article, we will explain how you can change the phase on your subwoofer to achieve a better sound, the reasons why you should do so, and some extra tips to help you achieve that perfect sound quality.

What Is Phase Control In A Subwoofer?

Phase control in a subwoofer is a process of adjusting the timing of the subwoofer's low-frequency sounds, so they are in sync with the main speakers. This results in a more seamless and accurate soundstage with better imaging.

In addition, phase control can help to minimize the build-up of standing waves in a room, which can cause bass frequencies to sound muddy and indistinct. This build-up of frequencies happens because every room has a resonant frequency and low frequencies travel easily through physical means.

The phase control in a subwoofer will essentially delay the sound by a few milliseconds to get synced with the other speakers of the system. There are two possible positions: phase 0 and phase 180.

The choice between the two will largely depend on a number of factors, including, but not limited to, speaker positioning, sound quality, and decibel reading.

The phase control in a subwoofer is, most of the time, located at the back of the equipment.

With a few things in mind, anyone can adjust their subwoofer phase setting so that you have the best sound quality possible, but in the end, it mostly comes down to personal preference and how much bass content you like to have when listening to your music.

How Many Types of Phase Control Are in a Subwoofer?

There are essentially two positions for the phase control in a subwoofer: phase 0 and phase 180. Each one represents a different time delay compared to the main speakers.

You should find the phase switch at the back of your subwoofer. Some subwoofers also allow you to set the phase to anything between 0 and 180.

1. Subwoofer Phase 0

When the switch is at phase 0, there will be no delay in the reproduction of the sound. It will play theoretically in sync with other speakers.

This setting is useful when you have the subwoofer facing the same direction as the main speaker as the peaks and dips of the soundwaves will match and result in a much bigger sound. This is the default setting found in most subwoofers.

The phase 0 setting should work in most situations, and if you have a small home theater setup, since most of the time, the speakers are located very close to each other.

2. Subwoofer Phase 180

As the name implies, when the switch is at phase 180, the polarity will reverse by 180 degrees, and there will be a delay of a few milliseconds between what is being played by the subwoofer and the main speakers.

This is useful when the subwoofer is too distant from the main speakers. Without the phase switch at phase 180, the peaks and dips in the soundwaves of both speakers would not match. This causes the system to sound flabby. Switching the phase is an easy solution for that.

Another situation where this setting is useful is when you have the subwoofer placed on the other side of the room compared to the main speakers or on adjacent walls since the added distance naturally delays the response between the two pieces of your audio setup.

3. Variable Phase

The variable phase is when a subwoofer allows you to set the phase value to anything between 0 and 180. This allows for a more precise setup but will take a few more steps to get right.

What is the Subwoofer Phase Switch Used For?

The phase switch in a subwoofer is used to adjust the phase of the speaker to avoid any clashing with the main speakers. It can greatly improve sound quality and improve the bass content in your music.

To understand why a phase switch is needed, we need to understand how sound waves interact with each other.

Every continuous sound wave has peaks and dips. When you have two speakers playing the same audio content, these sound waves are naturally going to interact.

The audio is in-phase when the peaks and dips of the sound waves match each other. In this case, the subwoofer will enhance the sound of the main speakers and vice versa. This is the desired scenario.

The audio is out-of-phase when the peaks and dips of the sound waves don't match. The result is a flabby sound that lacks definition since both sound waves are canceling each other.

The phase switch is there to solve this problem and make the audio in phase again by syncing the subwoofer and the main speakers.

How To Tell If Your Subwoofer Is Out of Phase?

As we said, an out-of-phase subwoofer sounds flabby and weak. The low frequencies are deeply affected by this situation, but how to tell if your subwoofer is out of phase?

The best way is to listen and let your ears be the judge. If you don't have a trained ear, we advise using a song that you know well or simply a test tone.

Remember to try different settings to see which one sounds the best. That is the most foolproof way of judging if your subwoofer is out of phase or not.

Check out our article on ‘Dual Subwoofer Placement‘.

Subwoofer Phase and AV Receivers Distance Setting

Many AV receivers offer a distance setting, which you can use to adjust your audio system with more precision. If you're using this setting, the phase switch on a subwoofer should be set to phase 0.

If you don't know where the distance setting is located on your AV receiver, the information is most likely located in the manual.

The distance setting in an AV receiver will allow you to delay the audio so that the sound of the subwoofer and the main speakers reach your ear at the same time. The setting will, basically put, do the same thing as the phase switch on your subwoofer but with more precision.

The easiest way to set the distance setting in your AV receiver is to use an SPL meter. You can download an SPL meter app on your smartphone if you don't have one.

Below, we will explain in detail how you can adjust your AV distance setting using a test tone.

Read More: 6 Best AV Receivers For Music

How to Set AV Distance Setting

With an SPL meter in your hands, you will need a test tone. You can easily find one on YouTube by searching for “subwoofer test tone” or downloading it online.

First, you need to set up your audio system correctly, starting with the center channel. Your AVR should be in Dolby Surround mode, so you get the signal from your center channel and subwoofer only.

The left and right channels should be set to Stereo Surround Mode.

After the initial setup, you should invert the phase on your subwoofer. This is easily done by flipping the phase switch, usually located at the back of the equipment.

Now, it is time to play the test tones. You should know the crossover frequency of your subwoofer, that is, the frequency where there is a high cut on your subwoofer reproduction. This should be easily found in the manual or at the back of the equipment, but as a rule of thumb, keep it at 80Hz.

Play a test tone correspondent to the crossover frequency of your subwoofer. Use your SPL meter to measure the output of the system standing 1ft in front of the listening position.

From there, you can start increasing the subwoofer distance setting in your AV receiver while paying attention to the SPL meter. When you find the number that gives you the lowest SPL reading, that is the optimal distance setting.

Now, invert the phase on your subwoofer again and listen to check if everything sounds great.

Remember to do the steps carefully since the difference between the settings can be very subtle.

Read More: 2 Ohm vs. 4 Ohm Subwoofer

Should I Set the Subwoofer Phase to 0 or 180?

Setting your subwoofer phase to phase 0 or phase 180 comes down to the perceived audio quality. That is, you should use your ears to judge if your system's low-frequency content is being reproduced correctly.

You must also decide the correct setting based on the subwoofer's positioning relative to the main speakers and the decibel reading. All of these factors will come into play when deciding where to keep the phase switch, and we will explain each one of them in detail below.

Subwoofer Phase and Speaker Positioning

This will largely depend on how your subwoofer is positioned relative to your main speakers. In many home systems, both speakers are near each other. There are a few rules of thumb to know whether or not you should flip the phase on your subwoofer.

If your subwoofer is positioned facing the same direction as your main speakers, which is the most common scenario, then you most likely won't have to flip the phase switch since there will be a minimal delay between both speakers.

If you have your subwoofer facing the opposite direction of your main speakers or they are on the opposite side of the room and adjacent walls, then it is recommended to flip the switch to phase 180.

Remember that these are only arbitrary rules and you should try different settings in order to have a more precise configuration, since not every audio system is equal.

Sound Quality

This is the most crucial factor. Based on the sound quality of your audio system, you can judge whether or not you should flip the phase switch on your subwoofer.

The easiest way to do this is to play a song you know well and judge if the bass is sounding good or if it sounds flabby and without enough power.

The low frequencies and bass won't sound quite right when the sound is out-of-phase. If that's the case, you should try to flip the phase switch on your subwoofer to make it in phase again.

You can also experiment with positioning your subwoofer relative to your main speakers to see if the problem persists.

Decibel Reading

This is the most precise way to determine whether or not you should flip the phase switch on your subwoofer. You can use an SPL meter if you have one. If you don't, then there are a lot of apps available for iPhone and Android that can do the job quite well.

With an SPL meter, you can experiment between phases 0 and 180 while monitoring which setting gives you the most presence on the frequency graph in the crossover area of your subwoofer.

If you don't know the crossover area of your subwoofer, it is generally located around 80Hz; that should be a great rule of thumb to start. Make sure to check the manual as well.

If your subwoofer has a variable crossover frequency, then the knob is usually located at the back of the equipment and you can check it there for this information.

Also Read: What Does a Speaker Switch Do?

Frequently Asked Questions

Does Subwoofer Phase 180 Sound Muddy?

Switching the phase on a subwoofer can be useful in achieving optimal bass response, but some people find that setting the subwoofer to phase 180 degrees results in a muddier sound.

There is no right or wrong answer when it comes to the subwoofer phase, so ultimately it is up to you to experiment and see what sounds best in your system. If you think the subwoofer sounds muddy at phase 180, try flipping the switch and see if you prefer the sound with the subwoofer in phase with the other speakers.

Does Phase Matter to Subwoofer?

Yes, the phase on a subwoofer is very important because, as we said earlier, the sound of the sub must complement the sound of the main speakers. An out-of-phase subwoofer will sound flabby and weak, especially when it comes to low frequencies and bass response.

Subwoofer Crossover Frequency

The subwoofer crossover frequency is the specific frequency where there is a high-cut filter in the subwoofer. It means that the subwoofer will only play frequencies below this threshold.

Many subwoofers have an adjustable crossover frequency, usually located at the back of the equipment. If yours don't have one, then the crossover frequency is most likely in the manual.

This is important information if you want to test the phase of your speakers using an SPL meter.

What does an Out-of-Phase Sub Sound like?

An out-of-phase subwoofer sounds flabby and imprecise. The low frequencies don't sound as powerful as an in-phase subwoofer. It is something very easily perceived by trained ears.

The easiest way to judge if your subwoofer is out of phase is to play a song you know well or use a test tone with low frequencies.

Tip: If you haven't bought a subwoofer yet, check out our  8 Best Budget Subwoofers [The Ultimate Guide] article for a few affordable options.

Conclusion

As you can see, setting the phase on your subwoofer is an easy task if you keep a few important things in mind, such as your system's setup and the positioning of your speakers. The phase switch is there to help you achieve the perfect sound quality and decent bass response.

If you notice that the bass in your home theater or car audio is sounding flabby and weak, then the subwoofer is likely out of phase. Don't hesitate to follow the steps mentioned in the article.

Ultimately, let your ears be the judge. There's no right or wrong when it comes to setting up your subwoofer phase to 0 or 180. Some people prefer a solid, thumping bass in their music, while others prefer this frequency range to be a little quieter.