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Discussion Starter · #1 ·
I am hoping you guys could help me with a box design for 2 13Ov.2 D4 subs. http://www.edesignaudio.com/product_info.php?t=2&products_id=35
I will be making 2 boxes, 1 sub in each and would like to do a down firing design with a foot print of about 14x14. I was previously going to do 15x15x30 with a 4 inch aeroport on top (ED recomendation), but am thinking I would like a box a little narrower and taller, and possible use a slot port (a 4 inch hole on top of my sub is just asking for my friends to drop a beer bottle down it!!)
I would like to keep tuning around 20hz. My laptop took a dump so I am using my work computer, so I can't run WinISD, or the other box programs. This of course gives the impression that I would know what I am doing once in the programs, and I wouldn't. lol I am more of a "just tell me what to build" kinda guy.
I will be powering them with an EP2500 wired to 8 ohms each channel.
Thanks so much for any help.
Cody
 

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I think there is something wrong with the parameters on their site. I hope someone will inform us the correct parameters...
 

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Vas and Sd, Re and BL values do not seem to be in accordance with each other
 

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Mike, can you pls try to model this sub? I am having some problems ...
 

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Modeled these some time ago and abandoned it-can't get flat freq resonse-always a wicked peak at 65hz. The best i could come up with was 3.5cuft tuned to 23hz with a 4 inch port 15.8 inches long. With the foorprint you want, thats a tall sub that might have some problem with standing waves due to the unusual depth behind the driver. You could probobly reduce the effect with some heavy damping at the top of the box, you don't want that long backwave coming back at the cone. As for the slot port, I would increase the footprint to 14x18 and downfire the port with the driver. This will decrease enclosure height and should help with group delay. Hope this helps.
 
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Discussion Starter · #11 ·
They didn't mention how long. They said just to get one and slap it in, no need to trim. So I guess how ever long a 4 inch port comes.
Thanks for the info mayhem, I certainly wouldn't be against a 14x18 foot print. **** in all honesty, I am pretty open. WAF is a slight factor, but she is usually pretty flexible.
Can you tell me more about the slot port enclosure you mentioned, out side demensions and such?
I appreciate all the help so far guys.
 

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Pls show us the parameters you used.
 

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I'm using Unibox and i get nice flat response UNTIL i enter the Le value that wasn't posted on their site in the T/S paramaters. Someone measured it on another forum( asked ED online chat-got no answer) at 1.20mH-if you add that parameter in instead of leaving it blank, the curve changes DRAMATICALLY! Try it, you'll be shocked.

The port i mentioned was round, sorry about the mixup-Haven't gotten the most positive feedback from slot port builders/users-air velocity increases dramatically in the apex creating odd effects and compression as to what i've heard from others. Too much of a pain to design as well. The 18" depth will allow an offset 4" port on the same baffle as the driver. Some builders have reported depth of tune increases when the port is corner loaded in the enclosure. I understand it's not suggested just for that reason-unpredictable outcome from model but i say what the ****,if i can pick up 3-4 hz in the same length port-go for it-we're not talking critical values as if in a three way Hi-Fi speaker. The low end of the Freq response isn't going to be crossed to anything anyway!
 

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What FS, Vas, Re & Sd did you use? WinISD doesn't seem to agree with the value on the site simultaneously...
 
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Discussion Starter · #18 ·
Guys I certainly appreciate all the work and discussion you guys are doing on this. Just as a heads up, I am completely lost after the 14x18 part!! LOL I have tried learn how to read these graphs and understand, but no go so far! This will be my first venture in HT DIY and even my first venture outside of HTIB, except maybe a powered KLH 12 several years ago. So what I am trying to say is I will be easily impressed. Just wish I could pitch in more to this convo! I do promiss pics of me making a mess though.
 

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Sorry Happy, we're just tryin to find the best volume and tuning frequency for you. I suggest 3.5cuft NET volume-which means the remianing internal volume figuring the volume of the port and driver and the internal dimensions of your box. Lets say your box measures internally 12.5 inches x 16.5 inches x 34.5 inches.That will give you 4.1 cubic ft gross. Subtract from that the volume of the port,driver and bracing to result in your final volume. This is the volume we enter into modeling programs using the drivers electrical and mechanical properties to determine the best tuning frequency for the application. For HT use, many of us will look to tune as low as possible to get the most low Freq content from soundtracks as possible. For 50/50 use i'll tune a little higher or just go sealed.
I you used a round port 4" diameter, 15.8 inches long for a tune of 23hz, it would be about .13 cuft-subract that from the gross volume. Then subract the volume of the bracing, plate amp,etc to arrive at the final volume.
 
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