Polarity, delay and phase in sub alignment

John Mulcahy · Apr 2, 2025

Pat Brown of SynAudCon has produced a great set of videos covering the role and effect of polarity, delay and phase in aligning mains and subs. REW's tone burst generator and Scope are used to show the effects of each parameter in the time domain, making it easier to see what is going on. You can find the videos here: Mains/Sub Alignment - A Different Take.

Breeman · Apr 2, 2025

Hi John, Just curious to know if Pat's method is any didifferent to the sub to mains alignment process of using the Impulse alignment option within the Alignment tool

John Mulcahy · Apr 3, 2025

There are some similarities, as Impulse alignment uses filtering at the alignment frequency that produces wavelet-like responses and can determine polarity and delay corrections.

martin1234 · Apr 26, 2025

impresionante. Ya con ganas de probarlo, excelente informacion. A pesar de haber usado el rew para mi tesis final de grado, siento que lo explore muy poco, nunca he usado el osciloscopio.

JStewart · Apr 27, 2025

Thanks for sharing this, John. The spring analogies used really provided clarity to the concepts.
Bookmarked.

FargateOne · Apr 27, 2025

wow! merci

AnthonyLoFi · May 6, 2025

Thank you John. And thank you Pat for allowing us to view your excellent series of explanations and implementation.
Although I believe this is targeted at the large installation market, I would assume the fundamental scientific principles used in this method can be applied to a home stereo installation that includes separate sub woofers.
I am going to attempt your procedures on my system which requires nothing more than my time and furthers my education on audio reproduction. Thank you again.

Kevin G · May 10, 2025

I just watched Pat's videos. It will take a bit for me to absorb all of that info. Thank goodness Pat is a fantastic teacher. Hopefully, I can make use of his lesson this weekend. It's so frustrating to me to KNOW that my system is still crap even after everything I've done before is getting me closer to being correct. Tuning a 9.2.4 room seems like a monumental task. Learning how to use John and Sonny's fantastic REW software is at least 80% of that task. I only have a basic AV processor and 2 SVS "Pro" subs with built-in DSP. I pray that all of this effort will be worth it.
I have a worry that adjusting delays and distances will further impact the "lip sync" issue I can't currently correct. It's like I need to have negative lip sync adjustment. Weird!

Mike0815 · May 15, 2025

Hello,

Could it be that generator setup is outdated in these videos or some bug with REW?
With newest REW it is not possible to set 6.5 cycles with Hann in Tone burst like shown there. Bursts are much longer. I do help myself using CEA-2010.

John Mulcahy · May 15, 2025

Mike0815 said:
Could it be that generator setup is outdated in these videos or some bug with REW?

No, perhaps you have got your settings wrong.

Kevin G · May 16, 2025

Mr. Mulcahy,
How do we make the connections to take the measurements as Pat has shown in his very nicely done video?
Currently, I have been using my UMIK-1 for all of my very amature testing and adjustment of my 9.2.4 system.
Can my UMIK-1 be used to make the same measurements as Pat has done?
I'm considering the purchase a Zoom UAC-232 interface. Will it work and would it be helpful with using your wonderful REW software?
My audio skills are low at this point and reading the REW website and watching videos is creating a blur in my mind.
Any help in setting up REW in my Win10 PC and UMIK-1 that you can provide is greatly appreciated.
BTW, A huge thank you for your efforts in building REW. Sir, you deserve a medal.
Please have a great day, Kevin

John Mulcahy · May 19, 2025

Kevin G said:
Can my UMIK-1 be used to make the same measurements as Pat has done?

No, the measurements use a loopback connection from an interface output to an interface input as a reference.

Kevin G said:
I'm considering the purchase a Zoom UAC-232 interface. Will it work and would it be helpful with using your wonderful REW software?

Spec looks good, but it is overkill for acoustics measurements. A much cheaper interface would be fine.

Kevin G · May 19, 2025

John Mulcahy said:
No, the measurements use a loopback connection from an interface output to an interface input as a reference.

Spec looks good, but it is overkill for acoustics measurements. A much cheaper interface would be fine.

Thanks John!
Then is just my Umik-1 enough for the measurements I need to calibrate my system? Or, do I actually need an interface and analog microphone(s)?
Also, I would like to learn your software well enough to warrant buying the "Pro" version. Or, don't I need it for home audio calibration?
Can you please recommend a route to take for me to learn how to properly use your grand creation?
Thanks again and please have a great day, Kevin
BTW, A donation to the cause is coming your way as I have the means.

John Mulcahy · May 19, 2025

Kevin G said:
is just my Umik-1 enough for the measurements I need to calibrate my system?

Sure.

Kevin G said:
I would like to learn your software well enough to warrant buying the "Pro" version. Or, don't I need it for home audio calibration?

No, everything you need is in the free version.

Kevin G · May 19, 2025

John Mulcahy said:
Sure.

No, everything you need is in the free version.

Thank you and I wish you and yours all the very best.

Polarity, delay and phase in sub alignment

John Mulcahy

REW Author

Breeman

Member

John Mulcahy

REW Author

martin1234

Registered

JStewart

Senior AV Addict

FargateOne

Member

AnthonyLoFi

New Member

Kevin G

Member

Mike0815

Member

John Mulcahy

REW Author

Kevin G

Member

John Mulcahy

REW Author

Kevin G

Member

John Mulcahy

REW Author

Kevin G

Member

Popular tags