Cross Correlation and Vector Average Measurements

mmaresg6 · 2024-10-29T20:32:50-0500

REW newbie here reaching out to advanced REW users. I reached out to OCA for Cross Correlation Time Alignment and Vector Average advice and recommendations to time align and EQ my 4 subs for 3 seats. I did three measurements for each of my seats, followed the steps to Cross Correlate and Vector average the measurements. EQed my subs to my preferred house curve, ran the predict function but when I measured to verify my predict house curve the verified measurement looked totally different that the predict. For my REW measurement, I used 0 to 24000Hz range, used "Used acoustic timing reference for my Timing. Does anyone have any idea as to what why the actual and the predict are different and what I might be doing wrong? The verified measurement has a null at 62.5 Hz and levels off up to the 100Hz. I'm very confused.

sm52 · 2024-10-30T05:12:02-0500

The main reason for the discrepancy is the room with its unpredictable reflections. There is no program yet that could predict how reflections will change. The way is so. Made changes and checked them. Made other changes and checked them. At some point you will understand which option you can choose.

mmaresg6 · 2024-10-30T10:23:10-0500

sm52 said:
The main reason for the discrepancy is the room with its unpredictable reflections. There is no program yet that could predict how reflections will change. The way is so. Made changes and checked them. Made other changes and checked them. At some point you will understand which option you can choose.

Okay, I understand better now why the discrepancy. I'll do some more testing. Thanks for the feedback!

moedra · 2024-10-30T16:06:05-0500

If you make correction filters from vector average responses instead of dB or RMS responses, there will always be differences because the vector average is not a true representation of magnitude like a dB or RMS average is.

JStewart · 2024-10-30T19:36:08-0500

mmaresg6 said:
REW newbie here reaching out to advanced REW users. I reached out to OCA for Cross Correlation Time Alignment and Vector Average advice and recommendations to time align and EQ my 4 subs for 3 seats. I did three measurements for each of my seats, followed the steps to Cross Correlate and Vector average the measurements. EQed my subs to my preferred house curve, ran the predict function but when I measured to verify my predict house curve the verified measurement looked totally different that the predict.

Was this what OCA recommended? I suspect not for multiple seats. Could be wrong, though. Can you link his video or whatever you got the method from?

It is possible to measure, use a target curve and calculate filters that will yield a matching measurement at each of multiple locations. To do that you need to either use the freeware MSO multi-sub optimizer at

Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software

The benefits of multiple subwoofers are maximized using Multi-Sub Optimizer software for lowest seat-to-seat frequency response variation and highest SPL.

www.andyc.diy-audio-engineering.org

or use hardware that will run Dirac Live Bass Control which you will pay for.

Dirac Live Bass Control

Dirac Live Bass Control. Automate subwoofer optimization for a strong, smooth, and refined bass response in all listening positions.

www.dirac.com

JStewart · 2024-10-30T19:39:30-0500

Here’s a post I did about MSO back in 2017 before I could spell optimize

Thread 'MSO - Multi-Sub Optomizer'
https://www.avnirvana.com/threads/mso-multi-sub-optomizer.1891/

mmaresg6 · 2024-10-30T19:47:55-0500

What's got me confused is the discrepancy between the predict and actual only happens when I use the multiple measurement cross correlation and vector average. When I use the single mic measurement method there is no discrepancy. See attached.

mmaresg6 · 2024-10-30T20:00:48-0500

JStewart said:
Was this what OCA recommended? I suspect not for multiple seats. Could be wrong, though. Can you link his video or whatever you got the method from?

It is possible to measure, use a target curve and calculate filters that will yield a matching measurement at each of multiple locations. To do that you need to either use the freeware MSO multi-sub optimizer at

Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software

The benefits of multiple subwoofers are maximized using Multi-Sub Optimizer software for lowest seat-to-seat frequency response variation and highest SPL.

www.andyc.diy-audio-engineering.org

or use hardware that will run Dirac Live Bass Control which you will pay for.

Dirac Live Bass Control

Dirac Live Bass Control. Automate subwoofer optimization for a strong, smooth, and refined bass response in all listening positions.

www.dirac.com

This is the link to the video where I got the recommendation from OCA. BTW, towards the end of his response he mentions and make recommendations of MSO for 4 sub arrangements.

mmaresg6 · 2024-10-30T20:04:09-0500

My next move is to dig deep into MSO, learn how to use it and try it and see what results I get for my open concept living room and 4 sub setup. Thank you for your feedback and suggestions. Appreciate it.

Cross Correlation and Vector Average Measurements

mmaresg6

Registered

Attachments

sm52

Member

mmaresg6

Registered

moedra

Member

JStewart

Senior AV Addict

Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software

Dirac Live Bass Control

JStewart

Senior AV Addict

mmaresg6

Registered

Attachments

mmaresg6

Registered

Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software

Dirac Live Bass Control

Attachments

mmaresg6

Registered

Popular tags

OUR MISSION

Quick Navigation

Buy us a cup of coffee!