Time and Phase alignment of SPEAKER and SUBWOOFER using REW

Summary

In this video, Matthew POS from POS Acoustics discusses the intricacies of time and phase alignment for subwoofers and mains in audio systems. He explains that phase and delay are closely related, with time alignment being the priority for optimal integration. While achieving perfect time alignment can be challenging due to room modes and group delay, using tools like REW (Room EQ Wizard) can help. Matthew emphasizes that adjusting delay for time alignment is crucial, and phase issues can be fine-tuned using all-pass filters without disrupting time alignment. His advice helps users navigate the complexities of speaker and subwoofer integration.

Takeaways

• 😀 Time alignment between subwoofers and mains is the first step to achieving proper integration in a sound system.
• 😀 Phase and delay are closely connected, and time alignment affects both delay and phase.
• 😀 REW (Room EQ Wizard) is an essential tool for optimizing speaker and subwoofer integration by adjusting delay, phase, and frequency response.
• 😀 Subwoofers with continuous phase dials and tools like Mini DSP help with phase alignment, but time alignment is still the priority.
• 😀 Achieving perfect time alignment is difficult, especially with room modes and rising group delay in the system.
• 😀 To optimize integration, use a combination of time alignment, phase adjustments, and frequency response tuning, all of which are accessible in REW.
• 😀 The wavelet and peak energy curve in REW are crucial for assessing the system's overall performance, including phase and group delay effects.
• 😀 Phase anomalies are less noticeable than amplitude anomalies, so focus on achieving a smooth frequency response first.
• 😀 If time alignment and frequency response are optimized but phase still seems off, slight phase adjustments can be made, but they must not disrupt time alignment.
• 😀 All-pass filters are an advanced tool for adjusting phase without affecting time alignment or frequency response, making them ideal for fine-tuning the system.

Q & A

What is the primary focus of the video by Matthew from POS Acoustics?

The primary focus of the video is on optimizing the integration of speakers and subwoofers, specifically discussing time alignment, phase alignment, and delay, and how these elements are connected in achieving optimal sound quality.

Why is time alignment considered the most important aspect when integrating subwoofers with mains?

Time alignment is considered the most important because if the subwoofers and mains are perfectly time aligned, phase alignment will naturally follow. Achieving proper time alignment is critical for ensuring the best sound integration between the subwoofer and mains.

How are phase and delay connected in audio system optimization?

Phase and delay are intrinsically connected. While phase can be adjusted without directly changing delay using specialized filters, in most audio systems, changes in phase typically lead to changes in delay, making them difficult to adjust separately.

What challenges are encountered when attempting to perfectly time-align subwoofers with mains?

Perfectly time-aligning subwoofers with mains is difficult due to non-minimum phase behaviors caused by room modes, rising group delay, and the complexity of determining the exact time alignment number in real-world acoustics.

What tool in REW (Room EQ Wizard) helps with aligning time and phase?

The alignment tool in REW helps adjust delay and level to optimize time and phase alignment, but it doesn't directly adjust phase without affecting delay.

What is the purpose of analyzing the peak energy curve in REW when optimizing sound?

The peak energy curve helps visualize how energy is distributed across frequencies and can highlight issues like group delay or room modes that affect sound quality. A smooth curve indicates good integration, while irregularities suggest misalignment.

How can all-pass filters be used to improve phase alignment?

All-pass filters can be used to adjust phase without affecting time delay or frequency response. They allow for fine-tuning phase alignment, which may help resolve issues with phase integration and frequency response without disrupting the overall system performance.

What is the recommended approach if phase anomalies are still present after achieving time alignment?

If phase anomalies are present after time alignment is set, the recommended approach is to experiment with phase controls, but it's crucial to ensure that time alignment remains intact. Typically, adjusting delay first yields the best results.

Why is it important to adjust delay first rather than phase when setting up a sound system?

Adjusting delay first is important because it ensures that the system is time-aligned, which is crucial for proper phase integration. Changing phase without considering delay can lead to misalignment and poor frequency response.

What would happen if phase is adjusted without first ensuring proper time alignment?

If phase is adjusted without ensuring proper time alignment, it could result in a misaligned system, where phase integration appears correct, but the overall system may have poor frequency response and timing issues.