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15" WO with Exponential Variable Flare (Read 2623 times)
TheLaidBackGuy
Ex Member



15" WO with Exponential Variable Flare
12/09/06 at 01:38:34
 
I want to know what you guys think about this. I decided to build a modified WO and do some measurements on it for an electro acoustics project.

First I scaled up the ratios for 15" drivers and started building a WO today. The base and three sides are up and I need to go back tomorrow to finish the rest.

I want the horn flare to be made out of one continuous piece (per side) of probably MDF that I will cut channels into in order to bend it. I can't find anyone that has bendable plywood around right now and I need to finish this project fast.

I basically want to secure the throat on a pivot and be able to move the mouth left and right to different preset points. The mouth will be secured at different points and I can take measurements to compare the efficiency and linearity of different flare widths.

I will basically be building an enclosure for the subs (like the original WO) but have a flare over the top of that that can be moved. This way the enclosure size will not vary and I can minimize the variables while taking measurements.

By the way I am using IDW-15 subwoofers for the project since I read this enclosure is good for low excursion woofers. Plus I love their SQ and the 97.8db sensitivity.  ;)
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« Last Edit: 12/09/06 at 01:52:05 by TheLaidBackGuy »  
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60ndown
Ex Member



Re: 15" WO with Exponential Variable Flare
Reply #1 - 12/09/06 at 05:22:52
 
sounds like you have considerd everything. bending mdf like that might be tricky? cant quite  picture how the moveable horn is going to work? a picture sais a thousand words.
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TheLaidBackGuy
Ex Member



Re: 15" WO with Exponential Variable Flare
Reply #2 - 12/10/06 at 03:42:03
 
Ok here are the pics of some stuff I did today. Of course I didn't get it done. I estimated 2 days so it should take me 3 times that long. (hope not)
Sorry the camera on my phone was the only one I had. My friend has a rebel so I will be able to take better pics later.
I will be rushing a few parts of the enclosure in order to get it done for testing. Later I will go back and do it right before it becomes a coffee table.

http://www.cardomain.com/ride/486503/6
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TheLaidBackGuy
Ex Member



Re: 15" WO with Exponential Variable Flare
Reply #3 - 12/12/06 at 05:21:31
 
I added 3 more pics. You can kindof see the shape of what I want now.
Yes I know the corners are no even close to being sealed. They will be redone and some real love will go into this enclosure once school is over.
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musgofasa
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Re: 15" WO with Exponential Variable Flare
Reply #4 - 12/12/06 at 09:30:51
 
It will be very interesting to see how sensitive the overall enclosure is to tiny movements of your flare. I have thought of doing something similar with a much simpler, straight lines horn. I am looking forward to hearing your impressions on this one when you ar done.

Keep us posted!

Robert
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Braggi
Ex Member



Re: 15" WO with Exponential Variable Flare
Reply #5 - 12/12/06 at 18:32:09
 
Looks like an amazing project. I wonder about the (lack of) air space in there. Is there enough room for those big diaphragms to move or will they be over damped?

I think I'm expressing concern for my own project because I'm about to do something similar with a pair of 12"ers. I'll let you know how it works out.
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aznboi3644
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Re: 15" WO with Exponential Variable Flare
Reply #6 - 12/13/06 at 04:56:24
 
Damn nice amp man...how much did that thing set you back??
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J_Rock
Ex Member



Re: 15" WO with Exponential Variable Flare
Reply #7 - 12/17/06 at 22:36:05
 
First off- excellent MDF bending.  I tried it a few times, and I just decided to buy kerfkore from now on.  

Next, I think those 15s would do alot better by removing that strait piece you have on the sealed chambers.  Should give them a lot more air to move.

The hinge idea is excellent.  I assume you will use that initially to test out what works best, then fasten them down for the final assembly.

If that is the case- keeping the compression and sealed chambers may be a better option then enlargeing them like I suggested above.  That way the only thing effecting the output while you change the flares is the flares' positions.

Keep us posted- I love the ingenuity in your project so far!
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TheLaidBackGuy
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Re: 15" WO with Exponential Variable Flare
Reply #8 - 12/20/06 at 02:06:59
 
Alright I got one more pic up of the "final" project. This one was taken with my sisters 7.2 megapixel camera. oooOOOooo

I want to let you all know that I plan on rebuilding most of the enclosure to make everything more permanent. For the purpose of the class project I just needed a working enclosure that would give me some results.

The MDF bending was a pain. One flare ended up bending a little less than the other, at the mouth it ended up being about 2 inches off. I plan on remaking that one. I also plan on bending the triangle at the bottom.

From the results on my initial measurements I am concerned about the airspace too. I seem to be getting a nasty peak at 180Hz and dip at 70Hz. The volume is only about 1.1ft^3 and the IDW-15's want much more. I plan on making the volume larger. The spec sheet is here.
http://www.imagedynamicsusa.com/pdf/Discontinued/IDW15.JPG

I assume by the Amp you mean the Mcintosh... It set me back $900, but I feel like I have saved money since I don't feel like upgrading every month.

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« Last Edit: 12/20/06 at 02:07:40 by TheLaidBackGuy »  
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TheLaidBackGuy
Ex Member



Re: 15" WO with Exponential Variable Flare
Reply #9 - 01/18/07 at 17:07:29
 
I have had a little time to rebuild the WO the way I wanted. After analysis of the variable flare it became clear the best results propagate from the wider flare. Therefore I rebuilt it in the widest position (which also looks the best). I added 5 more pictures of the WO.

Unfortunately I was told to get the box out of our shop since district managers were coming to assess the cleanliness or something. So it is sitting at home, ready to have the inside painted flat black. After that I need to Prep the outside and would like to do piano black lacquer. Unfortunately it is snowing outside and the WO will probably sit in my garage until it gets warmer.

If someone wanted I could probably post my paper on the project, although I am rather critical of my own work and I am only a newbie at the art of horn enclosures. And you would have to keep in mind that due to all the non-idealities present in the system most of the paper is an approximation.


http://www.sounddomain.com/ride/486503/6
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