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PostPosted: December 7th, 2014, 1:57 pm 
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Joined: February 28th, 2013, 3:31 pm
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If anyone is interested in making a low cost mid bass line array, Parts Expess is having a sale on a closeout 8" driver for $9.00 each in quantities. With 5 mm Xmax, a combination of 8 or 9 per side would be killer as far as linear volume displacement and sensitivity. Here is a link:

https://www.parts-express.com/cs8-3-28- ... m--299-344

Tom


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PostPosted: December 8th, 2014, 8:23 am 
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Thanks Tom, that looks pretty good. Didn't see a response curve though.........any ideas?


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PostPosted: December 8th, 2014, 9:13 am 
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Joined: March 5th, 2013, 9:35 am
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Location: Highland, MD
Stuart,
There is Lifetime Tech Support from Parts Express (see eMail and phone numbers on their web site at right side of Tom's link.)
Or you can buy them and measure it yourself, then shape stuff as you go. :)

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PostPosted: December 8th, 2014, 9:31 am 
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WinISD says they need a really teeny box. Not sure if I did anything wrong, but I simulated several options, closed and open, as well as multiple drivers. Box sizes specified are so small, the drivers won't fit into the boxes. i.e., 8 drivers into a 0.355 ft^3 box (613 cubic inches)! So if the box were (inside dimensions) only 8" wide and 64" tall (hard to fit smaller than that in a line array) the box would have to be 1.2" deep! Driver depth is 3.75", so riddle me that!?!?


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PostPosted: December 8th, 2014, 12:36 pm 
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Did you remember to convert Vas from ft3 to liters? I get a 147l closed box for 8 drivers, which is a bit over 5ft3....

Roscoe

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PostPosted: December 9th, 2014, 9:56 am 
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If you remember my line array, it is in a dipole configuration so I didn't worry about box size. If you use a closed box you might want to break it into sections depending on the length to prevent any "organ pipe" resonances.


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PostPosted: December 9th, 2014, 11:28 am 
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Thanks Roscoe, that was my mistake. Tried to make all the unit conversions but missed that one! Now the numbers make sense .

If I were to do an open baffle arrangement, How wide should the baffle be and how low of a -3dB point might be expected?


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PostPosted: December 9th, 2014, 4:22 pm 
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Here is an interesting site:

http://musicanddesign.com/A_B_C_Dipole.html

If you are making a line array the rolloff will be not as extreme as this predicts because of the long dimension in the vertical direction. You can see from the attached photo the baffle is not much wider than the drivers. It works well to 80 Hz.

Tom


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56Speakers.jpg
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PostPosted: December 9th, 2014, 4:48 pm 
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Tom,

Tried the link. My anti-virus warned me. I ignored it since you sent the link. Wasn't too hard to clean up after pulling the plug and rebooting.

I'll look for other dipole design software.

Thanks,

Stuart


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PostPosted: December 9th, 2014, 6:11 pm 
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Location: Annapolis, MD
FYI: The URL that TOMP provided [musicanddesign.com] is John Kreskovsky site -- John uses javascript to build his site (I guess an IP protection attempt ...) -- so if your PC crashed, it is likely your JAVA is not up-to-date ...

$sitebuilder version="2.8.6" extra="Java(1.7.0_51)…
-->
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<html>
<head></head>
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<script type="text/javascript" async="" src="//np.lexity.com/embed/YW/56be0d1ac7669c53064f02ee9d31a9fe?id=34a32545bcbc"></script>
<script src="http://l.yimg.com/d/lib/smb/js/hosting/cp/js_source/whv2_001.js" language="JavaScript"></script>
<script language="javascript"></script>
<img border="0" src="http://visit.webhosting.yahoo.com/visit.gif?&r=http%3A//www.…5.0%20%28X11%29&s=1680x1050&o=Linux x86_64&c=24&j=true&v=1.2" style="display:none"></img>
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\\Charles

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