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SB Acoustics Textreme.
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Old 8th February 2020, 05:21 PM   #251
Jonasz is offline Jonasz  Sweden
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Quote:
Originally Posted by Oneminde View Post
I wonder about the dip, internal reflection perhaps ?
Same as a metal dome, acoustic cancellation maybe?
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Old 8th February 2020, 05:32 PM   #252
Oneminde is offline Oneminde  Sweden
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Comparing to the Be version, we might look at a result of material resonance. The Be is smoother all the way which is also evident in Bliesma T25B-6 Be tweeter. Due to this TX resonance and cone breakup, it cannot sound equal to that of its Be counterparts. Hold that thought since we have not seen any THD / IMD measurements yet. Satori motor is the same and voice coil, so only thing left is resonance or enhanced internal reflection or a combo.
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Old 8th February 2020, 06:05 PM   #253
Ro808 is offline Ro808  Netherlands
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Originally Posted by hifijim View Post
Having worked in engineering for 30 years, I can read between the lines and guess what "acoustical figure of merit" might mean...

The engineers at Eminence came up with a way of ranking diaphragm materials based on a number of attributes. this ranking method probably distilled all these attributes down into a single ranking number... which they coined as an "acoustical figure of merit"...

The marketing people, upon hearing the engineers talk about how Textreme has an incredibly high "acoustical figure of merit", foamed at the mouth and wet themselves... they then pushed these words into their marketing material... probably without the knowledge of the engineering folks.

I have seen this playbook many times...

Wrt diaphragm materials, an "acoustical figure of merit" would ideally be based on basically 3 acoustic properties: stiffness, (low) density, and internal damping.

The TexTreme biaxial weave has low density, but a triaxial weave - composed of three sets of yarns, which intersect and interlace with each other at 60 degree angles - has superior tensile properties compared to bi-plain and biaxial woven yarns. In addition, triaxial woven fabric has the ability to maintain structural integrity.
Attached Images
File Type: jpg Biaxial Schematic.jpg (41.1 KB, 476 views)
File Type: jpg TeXtreme 45 Grid Spread Tow fabric.jpg (59.4 KB, 476 views)
File Type: jpg Triaxial Schematic.jpg (73.9 KB, 476 views)
File Type: jpg triaxial-carbon-fiber-fabric.jpg (34.3 KB, 475 views)

Last edited by Ro808; 8th February 2020 at 06:09 PM.
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Old 8th February 2020, 06:13 PM   #254
Oneminde is offline Oneminde  Sweden
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Could it be that the be-directional material's failure point is evident in the tweeter but not in the woofer - aka, at relatively low frequency's the material integrity is good enough ?
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Old 8th February 2020, 06:31 PM   #255
Oneminde is offline Oneminde  Sweden
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Looking at the 6.5" TX, it looks like it shows critical faliour above 10kHz similar to the tweeter - just an interesting observation.
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Old 8th February 2020, 06:46 PM   #256
Jonasz is offline Jonasz  Sweden
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Quote:
Originally Posted by Oneminde View Post
Could it be that the be-directional material's failure point is evident in the tweeter but not in the woofer - aka, at relatively low frequency's the material integrity is good enough ?
Before you get too worked up regarding the 15k dip, it's the wrong graph. It's the same as the two 21mm tweeters. Check the pdf instead.
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Old 8th February 2020, 06:54 PM   #257
Oneminde is offline Oneminde  Sweden
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Dang it, their webpage is a mess atm - anyway. In the PDF we see a similar breakup as Al-Mg metal dome.
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Old 8th February 2020, 06:59 PM   #258
Ro808 is offline Ro808  Netherlands
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Similar to Hoffman's Iron Law (bass extension vs. efficiency vs. enclosure size), in general - as regards to traditional materials, you can only have 2 of the 3 properties (stiffness, (low) density, and internal damping) for a specific application.

For high frequency reproduction you'd want the stiffness of the triaxial weave (reduced breakup), but the higher density is prohibitive.

Last edited by Ro808; 8th February 2020 at 07:03 PM.
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Old 8th February 2020, 07:27 PM   #259
Ro808 is offline Ro808  Netherlands
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For low frequency reproduction, cone weight is of relative importance.
This cone weighs 10350 gr, but there's a motor with a BL of 110.0 Tm to get it moving.
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Old 8th February 2020, 11:37 PM   #260
hifijim is offline hifijim  United States
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Quote:
Originally Posted by Oneminde View Post
Comparing to the Be version, we might look at a result of material resonance. The Be is smoother all the way which is also evident in Bliesma T25B-6 Be tweeter. Due to this TX resonance and cone breakup, it cannot sound equal to that of its Be counterparts. Hold that thought since we have not seen any THD / IMD measurements yet. Satori motor is the same and voice coil, so only thing left is resonance or enhanced internal reflection or a combo.
I was thinking almost the same thing. I was expecting a response very similar to the Be version, but less expensive... maybe not...

Ro808 - I don't know if the textreme diaphragm is a single layer, it may be, but I tend to doubt it... if it is multi layers, they could use a combination of 0/90 and +45/-45 layers exclusively. it is not necessary to use 0/60/120 triaxial to achieve a good laminate. In aerospace applications, we almost always use 0/90 and +45/-45 layers. So without more knowledge of what Oxeon is doing, I am hesitant to lay blame on the 0/90 layup.
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