Subwoofer Phase 0 or 180

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When setting up your subwoofer, it’s essential to consider the phase setting, which determines the electrical delay applied to the subwoofer’s incoming signal. The phase can be adjusted between 0 and 180 degrees. Understanding the difference between the 0 and 180 settings will help you determine the proper setting for your subwoofer.

Setting the subwoofer phase to 0 means that the subwoofer and speakers are in phase. This setting is suitable when the subwoofer and speakers are placed in the same area and pointing in the same direction. It ensures that the sound waves from the subwoofer and speakers reinforce each other, resulting in a more cohesive and unified sound.

On the other hand, setting the subwoofer phase to 180 means that the subwoofer and speakers are out of phase. This setting is used when the subwoofer and speakers are positioned on opposite sides of the room and pointing at each other. It creates a situation where the sound waves from the subwoofer and speakers cancel each other out to some extent. This can be useful in specific room setups to minimize certain acoustic issues.

Ultimately, the choice between 0 and 180 degrees phase setting may come down to personal preference and the specific characteristics of your room. Some people prefer the sound produced when the subwoofer and speakers are in phase, while others may find that the out of phase setting sounds better to them. Experimenting with both settings and choosing the option that sounds better and provides the desired level of bass impact is perfectly acceptable.

It’s worth noting that when adjusting the phase setting, you may need to continuously adjust the volume of the subwoofer to achieve the desired sound balance. This ensures that the bass integration with the main speakers is optimal and the overall sound is enjoyable.

What Is Phase Control and What Phase Should You Set?

Subwoofer phase refers to the ability to introduce an electrical delay to the subwoofer’s incoming signal. This delay can be adjusted between 0 and 180 degrees, and it helps the subwoofer integrate better with the loudspeakers in the room. Let’s discuss the differences between subwoofer phase 0 and 180:

Phase 0 (Normal Phase): Setting the phase to 0 means there is no delay in the incoming signal, and the subwoofer and speakers are in phase. This setting is suitable when the speakers and subwoofer are placed in a similar area and pointing in the same direction. It results in constructive interference, where the sound waves from the subwoofer and speakers reinforce each other, creating a more powerful sound.

Phase 180 (Reverse Phase): Choosing a phase setting of 180 degrees reverses the polarity of the subwoofer, placing it in the opposite polarity of the loudspeakers. This setting is useful when the subwoofer is placed on a wall opposite to the speakers. It reduces destructive interference, meaning the subwoofer and speaker waves do not interfere with each other. However, one disadvantage is that this can cancel out the bass from the main speakers, reducing the overall bass output, which is not desirable.

Variable Phase: Some subwoofers offer a continuously variable phase control, allowing you to adjust the phase in small increments between 0 and 180 degrees. This provides more precise control over the phase matching between the subwoofer and speakers, minimizing losses due to cancellation and increasing the overall efficiency of the sound system.

It’s important to note that setting the phase to a value between 0 and 180 degrees can result in partial cancellation of the total signal. Therefore, a subwoofer with a continuously variable phase adjustment allows for better optimization of the phase relationship between the speakers and subwoofer, leading to improved sound quality and efficiency.

What Is the Subwoofer Phase Switch Used For?

A subwoofer phase switch is a feature found in some subwoofers that allows you to adjust the phase of the subwoofer’s output signal. The phase can be set to either 0 degrees or 180 degrees, depending on the switch position. This adjustment is important for ensuring proper alignment and integration of the subwoofer’s sound with the rest of the audio system.

When the subwoofer and main speakers are in phase, their sound waves align and reinforce each other, resulting in a more cohesive and powerful bass response. In this case, setting the phase switch to 0 degrees is recommended.

On the other hand, there may be situations where the subwoofer and main speakers are out of phase due to their physical placement or room acoustics. In such cases, setting the phase switch to 180 degrees can help to correct the phase mismatch and improve the overall sound quality.

Some subwoofers offer a variable phase control, allowing you to fine-tune the phase adjustment to specific degrees between 0 and 180. This provides even greater flexibility in optimizing the subwoofer’s performance in your specific listening environment.

It’s important to note that the optimal phase setting may vary depending on the room acoustics, speaker placement, and personal preference. Experimenting with different phase settings and listening for the best bass response is recommended.

Subwoofer Phase and Positioning

The phase switch on a subwoofer is used to ensure proper alignment and integration of the subwoofer with the main speakers. The recommended phase setting depends on the positions of the main speakers and the subwoofer in the room. Here are some general guidelines:

Subwoofer and Speakers on the Same Side of the Room: If the subwoofer and speakers are placed on the same side of the room and are pointing in the same direction, it is generally recommended to set the phase of the subwoofer to 0 degrees.
Subwoofer and Speakers on Different Sides of the Room: If the subwoofer and speakers are positioned on opposite sides of the room and are pointing towards each other, it is typically recommended to set the phase of the subwoofer to 180 degrees.

Subwoofer Phase and AV Receivers Distance Setting

In addition to the subwoofer phase setting, modern AV receivers (AVRs) often provide a subwoofer distance setting, which offers a more precise way to time-align the subwoofer with the main speakers. If your AVR has a subwoofer distance setting and you are using a single subwoofer in your system, it is recommended to set the phase to 0 and utilize the distance setting instead.

The subwoofer distance setting takes into account the physical distance between the subwoofer and the main speakers, allowing the AVR to adjust the timing of the subwoofer’s output to align with the rest of the audio system. By inputting the accurate distance, the AVR can calculate the appropriate delay for the subwoofer signal, ensuring that the sound from the subwoofer arrives at the listening position in sync with the sound from the main speakers.

This method provides a more accurate and refined way to achieve proper time alignment and integration between the subwoofer and the main speakers. It takes into consideration the physical distance the sound waves need to travel, compensating for any potential delays and improving the overall coherence of the audio reproduction.

Therefore, if your AVR offers a subwoofer distance setting, it is advisable to use it in conjunction with a phase setting of 0 for a single subwoofer setup. This will help optimize the timing alignment and ensure a well-integrated and balanced sound experience.

What Is Receiver Distance Setting?

The distance setting on an AV receiver adjusts the time delays for the different speakers in a surround sound system. By properly setting the distance, you can ensure that the sound from all the speakers, including the subwoofer, reaches your ears at the same time.

In a scenario where the surround speakers are located closer to your listening position than the subwoofer, if all the speakers produced sound simultaneously, you would perceive a delay between the sound from the surrounds and the subwoofer. This delay can lead to distortions, inaccuracies, muddiness, or echoes in the audio.

To compensate for this, the AV receiver’s distance setting allows you to introduce time delays to ensure that the sound from each speaker, including the subwoofer, arrives at your ears simultaneously. By adjusting the time delays, the sound waves can be time-aligned, resulting in a more coherent and accurate audio experience.

In the example you provided, if the surround speakers are 4 ft from your head and the subwoofer is 12 ft away, you would set a longer time delay for the subwoofer to match the additional distance it needs to travel compared to the surround speakers. This adjustment brings all the sounds into synchronization and creates a more seamless and balanced soundstage.

By using the distance setting on your AV receiver, you can optimize the timing of the audio signals and ensure that they reach your ears in a coordinated manner, enhancing the overall audio quality and eliminating any perceived distortions or inconsistencies caused by varying distances between the speakers and the listening position.

How To Set AV Receiver Distance – Measuring Time Dealy and Distances

To properly set the receiver distance setting without using measuring equipment, you can follow these general steps using an SPL meter:

Begin with the center channel: Set your AV receiver to the Dolby PLII surround mode or Dolby Surround, which will activate the center channel and subwoofer output only.
For the left and right channels (FL/FR): Set your AV receiver to the Stereo surround mode, which will activate the FL/FR speakers and subwoofer output only.
Invert the phase on your subwoofer(s). This can usually be done through a switch or setting on the subwoofer itself.
Obtain test tones: Download test tones of the desired frequency (such as 80Hz) from the internet or use available ones on platforms like YouTube. These test tones should be specific to the crossover frequency you want to set.
Place an SPL meter about a foot in front of your face at the main listening position.
Play the test tone through the system, focusing on the center channel for step 1 and the left/right channels for step 2.
Gradually increase the sub distance setting in the AV receiver in 1-foot increments.
Take note of the SPL meter readings as you increase the sub distance setting.
Choose the sub distance setting that gives you the lowest SPL reading. This indicates the best time alignment between the main speakers and the subwoofer.
Invert the phase on your subwoofer again, ensuring it is back to its original phase setting.
Finally, confirm if your subwoofer is in phase by conducting additional tests. You can refer to a guide on how to test if a subwoofer is in phase for more details.

The reason for inverting the phase during the measurement process is to make it easier to identify any lack of bass rather than focusing on the peak response. This helps you find the optimal sub distance setting for proper time alignment and bass integration in your audio system.

Subwoofer Phase and Positioning

The phase switch on a subwoofer is used to align the phase of the subwoofer with the main speakers. The optimal phase setting depends on the positioning of the subwoofer and speakers in the room. Here are some guidelines to help you determine the appropriate phase setting:

If the subwoofer and speakers are on the same side of the room and pointed in the same direction, set the subwoofer phase to 0 degrees.
If the subwoofer and speakers are on opposite sides of the room and pointed towards each other, set the subwoofer phase to 180 degrees.

Using an SPL Meter with Test Tones:

You can utilize an SPL meter or SPL app to measure the decibel output at a specific frequency range, typically the crossover region between the subwoofer and main speakers. Follow these steps:

Play a test tone in the crossover region (e.g., 80Hz).
Measure the decibel output using an SPL meter or SPL app.
Try different phase settings (0 or 180 degrees) and note the decibel readings.
Choose the phase setting that produces the highest decibel output in the crossover region. This indicates better integration between the subwoofer and main speakers.

What if You Don’t Have an SPL Meter:

If you don’t have an SPL meter, there are alternative methods to determine the best phase setting:

Use an SPL app on your smartphone as a substitute for an SPL meter.
Alternatively, you can temporarily reverse the polarity of the main speakers by swapping the positive and negative speaker wire connections. Listen for the most noticeable drop-off in bass response.
Leave the phase adjustor at that setting and reconnect the main speaker wires to their original polarity (+ to +, – to -). This should restore the higher output level.

Please note that the method mentioned above may not work for subwoofers with only a 0/180 phase switch. In such cases, a subwoofer with a variable phase control is required.

Prioritizing Sound Quality:

Ultimately, the most important factor in setting the subwoofer phase is achieving the best sound quality. While decibel output is a consideration, it’s essential to trust your ears and choose the setting that sounds better to you. Sometimes a lower decibel output can provide superior sound quality. Adjust the phase of your subwoofer and stick with the setting that offers the most satisfying sound experience.

What Should LPF of LFE Be Set To?

When configuring your subwoofer, the LPF of LFE (Low Pass Filter of Low Frequency Effects) setting is an important consideration. This setting determines the upper frequency limit at which the subwoofer handles low-frequency effects or bass in LFE content. Generally, it is recommended to leave the LPF of LFE at the default setting, which is typically between 80Hz and 120Hz. If you are not specifically considering LFE and setting the LPF alone, 80Hz is a suitable choice.

In some cases, automatic calibration systems like Audyssey MultEQ may set the LPF of LFE to 100Hz, but we still suggest using 120Hz. This is because LFE content is mixed up to 120Hz, and setting it lower may result in the removal of some audio content. However, if you find that setting the LPF for LFE at 80Hz sounds better to you, it is perfectly acceptable. Sound quality should be your primary consideration.

For adjusting the subwoofer distance, you can follow these steps:

Set your AVR to the Dolby PLII surround mode (Dolby Surround on Atmos AVRs) to enable output from the center channel and subwoofer only.
Set your AVR to the Stereo surround mode to enable output from the FL/FR channels and subwoofer only.
Invert the phase on your subwoofer(s).
Play a sine wave corresponding to your crossover frequency (e.g., 80Hz) and measure the output using an SPL meter positioned about a foot in front of your listening position (MLP).
Gradually increase the sub distance setting in the AVR in 1-foot increments (ensure you exit the distance setting menu on some AVRs for the new setting to take effect).
Choose the sub distance setting that gives you the lowest SPL reading. You can fine-tune further in smaller increments if desired, but 1-foot increments are usually sufficient.
Invert the phase on your subwoofer again.

The reason for inverting the phase is that an SPL meter makes it easier to identify a lack of bass rather than a peak. The sub distance tweak aims to flatten the response around the crossover region. The attached example illustrates the effect of the sub distance tweak, with the red line representing the response before adjustment and the green line representing the response after adjustment.

Please note that if you don’t have access to measuring equipment, you can use an SPL meter or SPL app on your smartphone, along with test tones that can be downloaded from the internet or found on platforms like YouTube.

F.A.Q

Does Phase Matter To Subwoofer?

The phase alignment between your subwoofer and main speakers is indeed crucial. When the subwoofer and main speakers are out of phase, their woofer cones operate in an unsynchronized manner, resulting in distortion. However, when the subwoofer and main speakers are in phase, their woofer cones move in sync, specifically at the subwoofer crossover frequency. This synchronization allows them to reinforce each other’s output, leading to improved overall performance and enhanced bass response.

Subwoofer Crossover Frequency

The crossover frequency of your subwoofer refers to the point at which your main speakers start to decrease in output, and the subwoofer takes over to handle low-frequency effects and bass notes. Modern AV receivers often include an auto EQ program that can analyze your speaker capabilities and determine the optimal crossover frequency automatically.

The recommended setting for the Low Pass Filter (LPF) of LFE, which controls the upper frequency limit of the subwoofer for LFE content, is generally set at 120Hz. However, it is also common to use a setting of 80Hz, as many LFE effects are rolled off after this frequency. Ultimately, the choice between 80Hz and 120Hz comes down to personal preference and what sounds best in your particular setup. Some users have found that setting it to 80Hz improves sound quality, while others prefer the default 120Hz setting.

There have been discussions in the subwoofer calibration thread regarding this topic, where some experts like Mark Seaton and Dr. Toole advocate for using an 80Hz setting. You can refer to that thread to learn more about their perspectives and experiences. Ultimately, it’s important to experiment and choose the setting that provides the best sound quality for your specific audio system

How Do You Set The Phase On A Car Subwoofer?

Play a track on the car stereo and turn up the volume more than halfway. • Open the trunk. • Observe the woofer cones. • Check up on the car amplifier. Flick the phase switch on the amp to either 0 or 180 degrees depending on how you have your subwoofer wiring setup.

What Does An Out Of Phase Sub Sound Like?

A common indication of a subwoofer being out of phase is a loss of bass response. You can assess this by listening to the bass and then changing the balance to the opposite speaker. If your speakers are out of phase, you will notice that one speaker produces more bass response than the other.

Conclusion

There is no inherent correctness in selecting either 0 or 180 degrees as the final phase setting for your subwoofer. As previously mentioned, it is important to consider the positioning of the subwoofer in relation to the main speakers when making this choice. If the speakers and subwoofer are not directly facing each other or located on the same side of the room, a practical approach is to set the phase to both 0 and 180 degrees and determine which option produces a louder sound. By choosing the louder option, you can optimize the phase alignment between the subwoofer and the speakers based on your specific setup.