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Old 30th March 2012, 10:51 AM   #181
DAMIC is offline DAMIC  Seychelles
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Hi,

Quote:
Originally Posted by von.ah View Post
I'm a total noob in planar theory. What's the rationale for non-parallel long sides (highlighted in the attachment) on your larger designs? This seems to be prevalent in a lot of planar speakers.
The shape with non-parallel longer sides simply gives the best frequency response on dipole speakers. Yu can check or simulate with Edge program :

Home of the Edge

regards,
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Old 30th March 2012, 07:41 PM   #182
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Exclamation trapezoidal design

Quote:
Originally Posted by DAMIC View Post
Hi,



The shape with non-parallel longer sides simply gives the best frequency response on dipole speakers. Yu can check or simulate with Edge program :

Home of the Edge

regards,
If that was the case, the bass panel could be rectangular like the tweeter...
But it's not is it !
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Old 31st March 2012, 01:10 AM   #183
Few is offline Few  United States
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Quote:
Originally Posted by von.ah View Post
I'm a total noob in planar theory. What's the rationale for non-parallel long sides (highlighted in the attachment) on your larger designs? This seems to be prevalent in a lot of planar speakers.
My understanding is that Apogee used the non-rectangular diaphragm shape, along with tension that was set differently at the top and bottom of the diaphragm, to tune the diaphragm to different resonance frequencies at different heights above the floor. The point was to avoid one dominant and audibly intrusive resonance.

It is often suggested that using non-parallel diaphragm edges prevents standing waves but the notion that rectangles support drumhead resonances while other shapes don't isn't correct. The spectrum of the resonances depends on the shape but the resonances are there whether the edges are parallel or not.

Few

Last edited by Few; 31st March 2012 at 01:14 AM.
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Old 31st March 2012, 05:23 PM   #184
YohY is offline YohY  United Kingdom
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Quote:
Originally Posted by Few View Post
....but the resonances are there whether the edges are parallel or not.

Few
I'd agree that the resonances are not totally eradicated, but are suppressed to a large extent..
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Old 1st April 2012, 12:57 AM   #185
Few is offline Few  United States
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Quote:
I'd agree that the resonances are not totally eradicated, but are suppressed to a large extent..
I don't agree that they're suppressed to a large extent but since I don't have data handy that I can present to back up my position I'll leave it at that. If someone has information that clarifies the situation I stand ready to admit I'm wrong.

Few
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Old 22nd September 2012, 01:16 PM   #186
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Been a while since i repaired these but wanted to see over a few months how they would perform and am happy to say its been fine so if anyone else has the same problems its nice to know these can be repaired in the field although its taken me nearly a year to source all the suitable parts and fix .
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Old 22nd September 2012, 01:17 PM   #187
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Old 22nd September 2012, 01:19 PM   #188
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Old 22nd September 2012, 01:27 PM   #189
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I don't know if it is a visual illusion but it seems like You have no lateral tension over the membrane as the side rubber seems to be slacking. True?

I see that You left the upper and the lower suspension out!
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Old 22nd September 2012, 01:28 PM   #190
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As you can see i have replaced the factory bass diaphram frame with one of aliminium but this did make it a lot harder job so i would not automaticaly recommend this mod as the factory mdf /ali strip is much easier to work with.
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