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Old 18th June 2011, 10:44 AM   #1
Veggiel is offline Veggiel  Belgium
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Default Advice for FAST with alpair 7

I want to build a FAST system using the Alpair 7 and Minidsp, the design would be quite similar to the B&W 802 diamond.
In the thread of the Blanda speakers Ikea spherical speakers, first build done. there where some interesting ideas of how to make the droplet like B&W does.

Now my question is would it be possible to use the 20cm Blanda bowls or do I have to use the 28cm ones? I will most likely cross them at 300hz.
So I was thinking that the smaller size bowls should still be ok if the don't have to go that low.

For the bass drivers I was thinking of using two CSS TRIO8 drivers per speaker, would these be good drivers for this purpose or are there better alternatives?
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Old 18th June 2011, 10:56 AM   #2
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Instructions on making a spherical enclosure(it's german but you will get the idea)

YouTube - ‪WERKANLEITUNG BETONKUGEL‬‏
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Old 19th June 2011, 05:38 PM   #3
Veggiel is offline Veggiel  Belgium
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That's an interesting way of building a bowl, but I think I will stick to the Blanda bowls for now.

So the question is can I go to Ikea and get a couple of 20cm Blanda bowls to use with the Alpair 7.
If I put this project in Winisd with a box of 3,5l everything seems fine, but perhaps there is something that I'm missing in order to make a good sounding speaker.
So every help is much appreciated.
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Old 19th June 2011, 07:02 PM   #4
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The A7 can be used in quite a small box if you aren't concerned about the bass. If too small you will get a bump at the bottom of the pass-band but this will be crossed out. The biggest concern with a very small box is that of internal reflections coming back thru the cone. This will be less an issue if you make an actual teardrop for the backhalf... if needed you can leave the skinny end open and make it into an aperiodic mid-TL.

Another issue with the smaller bowls is that more of the bowl has to be cut away to get the driver rebated. A quick sketch shows no mecahnical issues, but it will decrease your volume.

dave
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Old 19th June 2011, 07:17 PM   #5
Veggiel is offline Veggiel  Belgium
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Thanks for the informative answer, I will be making the actual teardrop shape like B&W so hopefully I won't have to much problem with internal reflection.

About the bass driver are the TRIO8's a good match for the alpair 7 or are there better alternatives?
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Old 19th June 2011, 07:31 PM   #6
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If you can find some Trio8s, they are an excellent woofer with good extention.

dave
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Old 14th January 2013, 11:26 AM   #7
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Im embarking on the same quest with B&W 800D as the initial idea....the ikea thread you mention was mine as well.

I hopefully looking to start producing these to order commercially. Looking into woofer choices now, but might be able to sell you the teardrop shape. Will be turned from 18mm baltic birch ply.

Thread of my progress located here:
Designing a cabinet for Mark Audio Alpair 7.3
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