Quick Tip: Speaker Pointing

This is the first of my Quick Tip posts.  These will include tips, tricks, or suggestions which don't need a lot of background discussion, or detailed explanation.

Pretty much regardless of the type of speakers you get, the output of your speakers will become more and more "directional" as you go up in frequency.  This makes speaker pointing a consideration in your audio setup.

The line straight out from the speaker is called its Axis.  The strongest output of the speaker will be heard at a location which is "on Axis", i.e., along that Axis line.  The more "off Axis" you get, the weaker the sound you hear.  HOWEVER, there's a strong frequency dependence on this.  Bass tones are not going to vary much at all "off Axis".  Indeed the bass response characteristics of your listening room will make much more of a difference in the bass you hear at different locations.

Mid range frequencies will have a fairly wide "dispersion" from good speaker designs.  You can position yourself a fair bit "off Axis" and still hear suitably strong, mid range tones.

But treble frequencies will attenuate sharply as you move "off Axis".  This is what is meant by saying they are "directional".

Check the Manual which came with your speakers, as it may very well include dispersion diagrams which show this -- i.e., how the output changes as you get off Axis by varying amounts.  Typically this will be diagrammed for an example, mid-range frequency and also an example, treble frequency.  Note also, the Manual may have DIFFERENT charts for horizontal and vertical dispersion.  It is common for speaker designs to have better dispersion horizontally than vertically.

The speakers tasked with carrying the highest quality audio in your system are the Front Left and Front Right speakers.  They will handle the most important musical elements, for example, as well as key sound effects for movies.  High quality Stereo Imaging depends on using these two speakers to full advantage.

And so the natural assumption is you should aim these speakers directly at center seating!

As it turns out, this is usually NOT the best pointing for these two speakers.  The reasons are more technical than we need to get into here, so let me cut straight to the chase.

Consider the Axis line from these speakers if they were pointing straight out from the screen wall towards the rear wall behind the viewers.  Now consider the Axis line if you rotated each of them to point directly at center seating.  The amount of rotation is called the "Toe In" of this pair of speakers.

The Rule of Thumb for horizontal pointing of the Front Left and Front Right speakers is their Toe In should be only 1/3 of the angle between those two lines.

That is, they should be Toed In a bit, but they'll still end up pointing more towards the rear wall than towards center seating.

Meanwhile, the Center and Surround speakers can be pointed DIRECTLY at center seating.

As mentioned above, the vertical dispersion of most speakers is not as good as their horizontal dispersion.  This means the Fronts, the Center, and the Surrounds should, ideally, all be installed at seated ear level.  If they are NOT placed at that height, then you should also look to adjust their vertical pointing.

Adjust the vertical pointing of all these speakers so their Axis crosses the center seating area at seated ear height.

If you have Height speakers in your setup, they too should be pointed at center seating.  For wall mounted Height speakers, pay particular attention to their vertical pointing.  Wall and ceiling mounted (or built-in) speakers may give you limited options for adjusting their pointing.  Don't go overboard trying to jury-rig something.  But if adjustment is available, take advantage of it.

Bass is NOT directional, so there's no need to point your Subwoofer in any particular manner in order to hear the full quality of its output.

What's more important is how the output of the Subwoofer "couples" to the geometry of your room in all 3 dimensions.  Shifting the Subwoofer a few inches left/right or front/back can make a BIG difference -- particularly if it is near a wall or corner, but even if it is in the middle of the room!  Rotating the Subwoofer will typically have only a comparatively minor effect -- unless it is right against a wall or corner.  So for the most part you can rotate the Subwoofer as looks best to you, aesthetically.  But if you can't find a location for the Subwoofer which suitably minimizes bass problems in your room, try rotating it as well for additional "fine tuning"; particularly, as just stated, if you are trying to use it positioned right up against a wall or corner.

Keep in mind any shifting or rotation of the Subwoofer will affect how it matches in Phase to your main speakers.  So plan on re-checking your Subwoofer's Phase adjustment afterwards to minimize cancellation between bass from the Sub and bass from the main speakers.