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Test CD : In Phase / Out of Phase test

I am looking for some help with the following problem?

Many test disks will play in phase and out of phase signals to assist in loudspeaker set up

In phase – my system plays back a signal that is tightly in focus and directly centered between the two loudspeakers. Good.

But, for out of phase – where playback should have no apparent source and seem like it is coming to you from everywhere in the room, my system whilst reproducing a signal that is diffuse and not centered between the two speakers – sounds stronger from the right speaker than the left, like the right speaker is the source.

I have tried the following

1. Changing the toe in of the right speaker so it does not point as directly at the listening position. The problem still remains

2. Swopping the left and right speaker – the problem still remains

3. Passing a 1KHz test tone and pink noise through the system and measuring SPL (dB) 1m from each speaker. The measurements were identical. Taking the same measurements from the listening chair however showed a 2dB stronger signal at the right side?

Any suggestions?
kiwi_1282001

Showing 2 responses by geoffkait

geoffkait's avatar
geoffkait
23,365 posts
 
It takes a lot of playing around with room treatment and speaker placement
to be able to get the out of phase track to sound like it is coming at you
from all around your room. But when the room has been treated properly,
I.e., primarily, but not limited to, with respect to echo and reflections, etc.
and you find the exact location for the speakers then you will hear the
sound all around you equally. But it is not something one can necessarily
obtain overnight. Tip: try placing the speakers closer together than you
normally would, say four feet apart with no toe in/toe out. Then play the out
of phase track to see if that improves the effect. Gradually move the
speakers farther apart and see if you can pinpoint the speaker location
where the out of phase track sounds best, when the sound appears to be
coming from all around the room equally, even from directly left and right of
your listening position and behind you.
geoffkait's avatar
geoffkait
23,365 posts
 
I guess I will clarify, too. The Test CD I was referring to is the XLO Test CD. TRACK 4 is the Out of Phase track for determining speaker locations without guesswork. The methodology of the Out of Phase track on the XLO Test CD eliminates a lot if guesswork involved in trying to find the optimum speaker placement in a given room strictly by ear. The problem with the move a little/listen a little method for speaker placement is you never know when you've found the optimum location. That's the beauty of the XLO Out Of Phase track - you can find the absolute best locations for the speakers. The disadvantage, if you want to call it that, of this methodology is that you have to address room anomalies in order to get to the point where you start hearing the effects of the Out of Phase track - where sound seems to be coming at you from all around your room, even from behind you. Unless room acoustics are addressed minimally it's virtually impossible to hear what they're talking about. As an old philosopher once said, "It ain't easy McGee."
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