# Phase Correction and Time Alignment in Car Audio



## gkannan (Dec 21, 2013)

Hello fellow members,

I am trying to tune my active car audio setup. It has a 3-way active head unit.
I also have both the Dayton and Umik USB calibrated mics and a multichannel USB sound card.

Is there a concrete method in REW to both phase correct and time align the individual drivers. I have read that with JRiver 20 there is no need for a loopback connection. Is it true?
If not then can someone provide a guide to do it.

Thanks


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum!

I know nothing of JRiver, but with REW time alignment requires a loopback reference and as such must be used with a standard mic. This isn’t a possibility with a USB mic.

Perhaps someone else can weigh in on JRiver.

Regards,
Wayne


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## natehansen66 (Feb 20, 2011)

J River is not a measurement sw so has nothing to do with that. I agree that a dual channel measurement is needed for time assignment.


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## Niick (Jan 2, 2015)

gkannan, good question!! I've been wondering the same thing lately. I actually perform PHASE alignment of driver to driver interactions on a regular basis at work. I am a custom car audio installer by trade (15 yrs). The software that I use at work is Smaart7. However, I've been thinking lately that it may just be possible to do the same thing with REW. If your car audio system is fully active AND you have a signal processor that can add delay (.02ms minimum increments) then you're good to go. If not, then you're gonna need to be able to adjust the physical positioning of the individual drive units, difficult in most car audio scenarios, as the locations for speaker placement are usually more or less fixed. Anyway, the process is actually quite simple with software that can perform real time transfer function measurements, like Smaart or even the iOS app Audio Tools (by Studio Six Digital) which has an in app upgrade called "Transfer Function", which is almost identical to Smaart7 's transfer function mode. Plus, Studio Six Digital's transfer function app is roughly 1/10 the price of Smaart. Google "Smaart phase alignment" or something to that effect, and you'll find a considerable amount of information on this very subject, keep in mind that the examples given are in a pro sound context, but the theory and application is the same, believe me, it works brilliantly on fully active car systems, I've got to get ready for work, if I don't quit typing and go I'm gonna make myself late, good luck!!


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## 808///M3 (Jan 9, 2013)

Give this a try - it requires time and patience, but it's free. Set time alignment to your ears, while sitting in your normal listening/driving position.

http://www.diymobileaudio.com/forum/how-articles-provided-our-members/96196-precision-time-alignment-using-only-noise-tracks-your-ears.html


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