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Discussion Starter #1
When choosing SW locations another question came to mind when I was choosing from two different distance settings to make in the AVR. I tested different distance settings and landed on 2.7m or 5.2m and they are both good compromises between L and R for support in the XO frequency at 80Hz but when I do a combined measurement of L and R speaker something happens, at 2.7m there is no gain at the XO but at 5.2m there is. The real distance to LP is now 3.2m (2 SW and 1 delayed to match the other ).

I have also tried to invert the SW at 2.7m and align the peak in REW at the distance of the one at 5.2m and that would not create the same outcome (not tested iRL).

What is the right approach, are they both right?

Or should I look at some other XO frequency?
 

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So if it looks good at 5.2 meters (seems as a large value to put in the AVR if the actual distance is 3.2 meters), in theory you should get the same if you invert the subwoofers and set distance to 3.1 meters in AVR or about there somewhat. If the crossover is 80Hz.
 

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Let the receivers room correction set the distance as it is seldom ever actual distance that is the correct setting for a sub.
 

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What is the right approach, are they both right?

Or should I look at some other XO frequency?
I am not completely clear on the exact changes made nor exactly what these measurements represent. I think that I have gleaned enough though to make some general comments:

> I understand that you found new locations for the SW and adjusted the MiniPSP delay to adjust for the distance difference of the 2 SW as you did before. This effort helped a lot. Looking at the SPL of these new SWs settings the choice you made appears to be a big improvement. Assuming there was not excessive EQ needed to achieve this result, I would not recommend any changes. Well done. :)

> The issue with differences in response between L, R, and L+R channels in the XO range near 80Hz is due to there being room modes that are very different between the L, R mains. Looking at the large phase differences in this 80 Hz range, there will be no setting that will be good for all 3 conditions. You evaluated several AVR SW distance settings an found that 5.2 m was the best because of the L + R condition. I think that is an important consideration as many have said that the bass range is often mixed as mono. I would use that 5.2 m setting.

> Looking at the phase chart there is closer phase agreement between L and R mains in the 60Hz range. From the phase analysis the 5.2 m distance setting will not work well with a 60Hz setting - poor phase matching to the SWs. The 2.7 m distance setting is ideal however. The 3 conditions are all in cooperation in that range and there will therefore be strong SPL support in that range. It is difficult to predict if the result of a change to a 60 Hz XO would be a net benefit however. The L, R mains phase difference still exist in the 80 Hz range and thus that range may not look any better for the 3 conditions. With significantly reduced SWs impact around 80 Hz there will be differences, but I would not predict which is better without seeing actual test results. It may well be a tradeoff.
 

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The '5.2 m' and the '2.6 m reversed' both are very good from an SPL perspective. They are the 2 best options for the 80 Hz XO. It would be hard to say one was 'better'. You may hear a difference with one or the other however. Many report being able to do so when the alignment is shifted 1/2 wavelength like this. From a phase tracking perspective they are different, but equally good. The SPL sags/nulls in the XO range just appear a little different.
 

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Discussion Starter #8
Thanks, good info and suggestions here. As for info I did a test with YPAO to see and it suggested a distance of 4.05m and 60Hz and normal phase but setts all speakers to Large.

But I will listen at the 5.2 and 2.6 R and see what I like best.
 

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It typically requires a change of 0.5 m from the 'ideal' setting to see any noticeable SPL change for an 80 Hz XO. 4.05 m and 4.20 m are functionally the same, so we have is good agreement with that setting.

I would definitely suggest setting the mains to 'small' however. The more overlap there is of the mains into the bass range, the more the mains will disrupt the SPL there. A 'Small' mains setting will also relieve some stress on the mains and thus provide lower distortion with higher SPL levels. There is also a slight change to the phase response with 'large' Vs 'Small' so there would be some small impact to the best distance setting. Maybe that is reason for small difference in suggested distance settings. These are likely to very minor concerns, so if you choose 'large' the difference may not be detectable.
 
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