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is there a tolerance for being on axis?

DLS79

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I'm designing my new office in cad for near-field listening, an that got me thinking.

In a perfect world the speakers would be set up in an equilateral triangle, and the user would be prefectly on axis at all times. In the real world people move around, turn their heads, slouch, etc, so it's not possible to always be perfectly on axis.

That leads me to the general question of how far off axis do you have to be, to hear detrimental effects?

To minimize some of the variables I thought a good way to visualize a set up would be to have a triangle coming out of the speakers with a given included angle. Where the left and right triangles overlap would form a diamond shapes "sweet/safe" spot. And that leads to the specific question, what would be a good included angle 5°, 10°, 20°?

Here is an example with a 20° included angle.
cone.png
 

GXAlan

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Download Meyer Sound MAPP XT to see the effect of comb filtering. It will only be accurate for speakers with similar dispersions but you can move a virtual mic and move speakers and angles to get some estimates. How it measures isn’t how it actually sounds though. Like our eyes scanning across the scene, we don’t sit perfectly still.

 
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DLS79

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Download Meyer Sound MAPP XT to see the effect of comb filtering. It will only be accurate for speakers with similar dispersions but you can move a virtual mic and move speakers and angles to get some estimates. How it measures isn’t how it actually sounds though. Like our eyes scanning across the scene, we don’t sit perfectly still.

I'll have to give that a try when I get home tonight.


I was thinking about it this morning, and a simple hack might be to take a look at @amirm's beam width plots. I took a look at several today and it seems like even crummy speakers are ok up to +-10° so an included angle of 20 degrees would be fine. Neumann KH-120 IIs or Genelec 8030Cs would probably be fine out to +-25°, 50° included.
 

GXAlan

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I'll have to give that a try when I get home tonight.


I was thinking about it this morning, and a simple hack might be to take a look at @amirm's beam width plots. I took a look at several today and it seems like even crummy speakers are ok up to +-10° so an included angle of 20 degrees would be fine. Neumann KH-120 IIs or Genelec 8030Cs would probably be fine out to +-25°, 50° included.

The interesting part is when you look mathematically at what happens if you are 10 and 9 degrees for your left and right speakers.

Again, it probably doesn’t matter but it makes you less worried about squiggles on the FR plot. Something may be great in mono but once you are in stereo and not sitting perfectly, it starts to look really ugly :)

You have to register for a free acct with Meyer Sound and then it’s a free download. It’s both a tool for Meyer Sound owners as well as a marketing tool. MAPP XT is 2D so it’s easier. Its default mode is vertical (for line arrays) but you can just switch it to horizontal when adding the speaker and mic. MAPP is fully 3D but interestingly does not have the Amie in it.
 
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