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Old 5th October 2012, 03:55 PM   #181
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Originally Posted by 6.283 View Post
But if you rotate the mid bass then the direct sound diminishes and I am not eve sure that there is a big issue in that range as the source is already directional, hence there is less room interaction.
How directional is dipole midbass up to let's say 400Hz? This is John's NaO Note:

Click the image to open in full size.
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Last edited by markus76; 5th October 2012 at 03:58 PM.
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Old 5th October 2012, 03:58 PM   #182
puppet is offline puppet  United States
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6.283, I wasn't talking about subs but about dipole midwoofer in the mains (>80Hz). Never seen a concept that would let the user rotate the midbass unit. This would be a significant advantage compared to a boxed speaker.
markus ... if the sub/woofer is xo'ed to mains around the Schroeder frequency what would be the point of rotating a mid/woofer in the mains? In a 2-way dipole main this would be problematic .. no?

My mains are HP to independent sub/woofers (in U frames) @116hz (LF cutoff) 4th order. I can't be the only person doing something like this.
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Old 5th October 2012, 04:03 PM   #183
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markus ... if the sub/woofer is xo'ed to mains around the Schroeder frequency what would be the point of rotating a mid/woofer in the mains?
There are still detrimental modal effects at higher frequencies. It's a gradual change, not a matter of on and off.
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Old 5th October 2012, 04:11 PM   #184
gedlee is offline gedlee  United States
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It does when the source is close.
I'm still not sure about that nearfield usage for subs, I've never tried it. I would be very concerned with localization of this source due to higher order effects that are not an issue for a distant sub. Closed boxes do minimize these effects. Port noise would make their use in this application untenable.
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Old 5th October 2012, 04:16 PM   #185
6.283 is offline 6.283  Germany
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How directional is dipole midbass up to let's say 400Hz?
Dipole midbass is no issue. So it will be a real dipole behavior and the directivity gain is 3 times over a monopole.
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Old 5th October 2012, 04:19 PM   #186
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I'm still not sure about that nearfield usage for subs, I've never tried it. I would be very concerned with localization of this source due to higher order effects that are not an issue for a distant sub. Closed boxes do minimize these effects. Port noise would make their use in this application untenable.
Attached is a near field measurement of a monopole vs. a dipole. Red is about 1ft. in front of the speaker, green and yellow 2ft. to the left and the right.

The modal effects are clearly visible in the monopole case. Overall the near field response is remarkably smooth in both cases when compared to the far field.
Attached Images
File Type: png nf-monopole-vs-dipole.png (83.2 KB, 109 views)
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Old 5th October 2012, 04:21 PM   #187
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Dipole midbass is no issue. So it will be a real dipole behavior and the directivity gain is 3 times over a monopole.
What do you mean by "Dipole midbass is no issue"? Placed at the wrong location there can be detrimental modal effects regardless of source type.
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Old 5th October 2012, 04:47 PM   #188
6.283 is offline 6.283  Germany
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What do you mean by "Dipole midbass is no issue"? Placed at the wrong location there can be detrimental modal effects regardless of source type.
I meant that at 400Hz it is easy to produce a real figure 8 pattern. That is not so easy let's say above 1.5KHz, where the directivy can vary which results in a different directivity gain.
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Old 5th October 2012, 04:48 PM   #189
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I meant that at 400Hz it is easy to produce a real figure 8 pattern. That is not so easy let's say above 1.5KHz.
The topic was LF.
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Old 5th October 2012, 04:52 PM   #190
6.283 is offline 6.283  Germany
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Sorry if thinking out loud confuses you.
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