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adding bracing to a finished big sub box

post #1 of 16
2/8/13 at 10:13am
Thread Starter 
I went and looked at this supposed 14cu ft box for sale . It looks to be built well, but not much bracing . There are 2 braces from side to side, on the top and bottom of the port . Then there are braces from the top that connect to the middle side brace, but not to the bottom of the box. No side bracing near the top from port to the top of the box. I hope its ok to post cl adds here , if not i will save the pic to . What do you guys think ? He said he used 2.5 sheets per box. The front has double 3/4 , all mdf .


http://buffalo.craigslist.org/ele/3569654872.html
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post #2 of 16
2/9/13 at 9:37am
Thread Starter 
Would it be better to just start a new build ?
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post #3 of 16
2/9/13 at 9:45am
I would be more concerned with the tuning frequency of that cab then the bracing. An 8" port will need to be very long, and the depth on that cab is the shortest dimension.


It looks like a copy of a JBL cinema sub

http://www.jblpro.com/catalog/General/Product.aspx?PId=206&MId=1
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post #4 of 16
2/9/13 at 9:52am
Adding bracing will suck lol. I'd start a new build IMO
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post #5 of 16
2/11/13 at 11:10am
Thread Starter 
Ok, the guy called me back yesterday . I guess I was the only one who had inquired about them. He said they were built for a customer that ended up changing plans. He just wants them gone from his place. For $100 ea he will help load them in his truck and bring them to me. I guess they are tuned to 20hz, I used winisd to model a couple of 18's that i have. The mach5 mj18 and rfc 1218 look decent. I told the guy i will let him know by Weds.
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post #6 of 16
2/11/13 at 3:15pm
Quote:
Originally Posted by Dezmond View Post

Ok, the guy called me back yesterday . I guess I was the only one who had inquired about them. He said they were built for a customer that ended up changing plans. He just wants them gone from his place. For $100 ea he will help load them in his truck and bring them to me. I guess they are tuned to 20hz, I used winisd to model a couple of 18's that i have. The mach5 mj18 and rfc 1218 look decent. I told the guy i will let him know by Weds.

For 200 bucks delivered, I think it's worth trying them out. If nothing else you have some firewood for next year. biggrin.gif
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post #7 of 16
2/11/13 at 6:06pm
At least look for used JBL 2242 or 2245 since the box looks like that's what it was meant for. Quite efficient >20 Hz....
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post #8 of 16
2/11/13 at 6:20pm
Sounds like a really good deal, even if he's BSing about the tuning point, you can always add a different port. An 8" port will need to be 18" long for a 20hz tune. The Dayton RS 18 models really well in that box even though its bigger then most people will use. A 1000 watt amp and a 18-20hz high pass filter will get you 118 db down to 21 hz.

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post #9 of 16
2/11/13 at 6:21pm
Thread Starter 
Yes I have one 2245 and 5, 2242's , 4, 4645c cabs and one 4645a . The 2002 rockford 1218 looks good for 60hz and under and has 19mm xmax . I am going to have them dropped off Wednesday .
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post #10 of 16
2/11/13 at 6:22pm
Thread Starter 
The port is 19 inches long 8 inch diam. He used a concrete tube .
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post #11 of 16
2/11/13 at 6:37pm
Sounds like an amazing deal, wish I lived near by so I could out bid you tongue.gif

Curious how much room he left from the inner port opening to the back of the cabinet wall? The box dosent look that deep.
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post #12 of 16
2/11/13 at 9:18pm
What thickness of material did he use? From the pics it appears to be 1/2". If that's the case you are definitely going to want some more bracing.
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post #13 of 16
2/11/13 at 9:30pm
Quote:
Originally Posted by bass addict View Post

What thickness of material did he use? From the pics it appears to be 1/2". If that's the case you are definitely going to want some more bracing.

From the OP
Quote:
The front has double 3/4 , all mdf

I think the pic is a little deceiving, but you can see what looks like two layers glued together if you look closely at the cutout.
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post #14 of 16
2/11/13 at 9:34pm
Quote:
Originally Posted by Jay1 View Post

From the OP
I think the pic is a little deceiving, but you can see what looks like two layers glued together if you look closely at the cutout.

I guess I should have read the OP better, lol.

It looked like 2 1/2" pieces glued together, but obviously tough to tell from a pic.
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post #15 of 16
2/12/13 at 5:00am
Thread Starter 
Its 3/4 mdf all around, the front panel is two glued together .
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post #16 of 16
2/14/13 at 8:57am
Thread Starter 
There here smile.gif We installed the rockford fosgate 1218 hx2's . They go nice and low and seem to handle all the power I can give them . The boxes do slightly vibrate when really cranking them. I had light on top of one and it moves a little when pounding. Next time i go to Walmart I will pick up a couple 10lbs of polyfill and stuff them . They have a slight echo sound when I run then at 100hz cross, hoping the fill will help. I been cranking that "scary Christmas" biggrin.gif
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AVS › AVS Forum › Audio › DIY Speakers and Subs › adding bracing to a finished big sub box