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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
rhljazz
1,252 posts
 
Using Stereophile test CD2 in my main system, I achieved results similar to yours. My speakers are not equidistant from the sidewalls. The whole system is shifted to the left side of the room and my listening position is centered between the speakers. In addtion to that, neither sidewall is similar as far as surface is concerned. Since the system sounds fine otherwise, I won't worry about it.

In my secondary system which is my reference system, the speaker position and the room are much more symetrical. The result here was an even shift between channels and a lack of central specificity. I never did sense the out of phase signal to envelope or wrap around the listening position. The speakers are postioned quite close to the sidewalls in this room with a fair amount of toe in. The seating position is also closer than in my main system.

You could experiment with some alternate speaker positions or try a few absorbers in different areas and see what happens.
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."
onhwy61's avatar
onhwy61
5,193 posts
 
Using the in phase/out phase track to position your speakers/listening spot may result in the best positioning for soundstage/imaging info, but it will not necessarily give you the smoothest tonal balance.
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