# Trust Audyssey on Sub distance?



## mc_lover (Aug 25, 2012)

Trust Audyssey on Sub distance?

The more I read about the Audyssey, about Subwoofer time align. The more confused I became.

- Audyssey says. We should leave Phase and Polarity at 0. 
- Other says (a) you are only aligning the timing for a limited ( I repeat LIMITED) frequency range, 
(b) you are only aligning the timing for a limited ( I repeat LIMITED) geographical range of the room. So the first thing we need to come to grips is with is the fact that our solution is by no means a global one. There are two decisions to make: what frequency range do we want to optimize for this limited partnership and at what location.

1-Do I have to trust Audyssey and do something more with Subwoofer-alignment.? leave it as it is.
Or go deeper into impulse response subwoofer alignment?


I went through this thread which is very good.
http://www.hometheatershack.com/forums/rew-forum/28894-case-study-sub-alignment-using-rew-v5-3.html

2-Is there any other thread about subwoofer impulse response time alignment that explain in detail?

Thank you


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## fusseli (May 1, 2007)

I lean towards trusting what Audyssey calculates, even if it returns a strange delay (or speaker distance). It should be giving an optimal value that factors in the crossover frequency(s) and the measured response at your listening location. Your listening location is all that really matters "geographically."


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## jtalden (Mar 12, 2009)

Audyssey should set mains to the actual measured distance and the SW should be close to the actual distance. The SW may be set 0-3 ft further than the measured distance and still be correct. Any setting in that range would sound correct to me. 

If we have a concern about the settings we can measure the SPL level using just the front 2 channels with several different SW distance settings in and around this same range. The correct setting is the one that provides the smoothest SPL response through the XO range, i.e., maybe 40 to 160 for an 80 Hz XO. We may need to smooth the traces using 1/6 or even 1/3 octave smoothing if it is difficult to tell which trace is best.

Room modes in the XO range can make it impossible to eliminate dips in the XO range so we are just looking minimize that problem. There shouldn't be any large peaks.

Some people like to invert the polarity of the SW and then look for the deepest null at the XO freq.


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