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Sub Box Ports

Old 04-03-2012, 01:18 PM
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Sub Box Ports

Hello everyone, i had just received a dual 10" sub box from a buddy of mine the other day and what i didnt notice when i got it was there seems to be (at least to me because i am a newb) that there are four ports or vents on the front of the box as well as two small holes (one on each side at the bottom.) My question for you all here is my plan of action for filling those up.....should i just close it off with mdf and sealent or should i just get some PVC pipe for port inserts? also i will post a picture shortly. Any help would be appreciated...

Last edited by Mikezord; 04-03-2012 at 04:39 PM.
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Old 04-03-2012, 04:44 PM
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Here are the images i said id upload....again any help appreciated thanks

Front Ports

Side Port

Whole Front
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Old 04-03-2012, 11:05 PM
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The holes on the side(s) are for cup terminals, so the speaker wire doesn't pass through the wood. You can buy them anywhere.
The rectangular holes on the front are for crappy horn tweeters. Seal those holes up using wood, good glue and a couple screws.
The round holes on the front are for ports. Figure out what the internal volume of the box is; if there is a divider in the middle so that each side it its own chamber, be aware of that. Figure out what frequency you want to tune your box to, and using any online port calculator, plug in your numbers to figure out what length of pipe to buy (obviously either buy the same diameter as the ex. holes, or enlarge the holes and buy appropriate diameter pvc).
Many of us tune around 36Hz-40Hz but thats a personal decision.
Good luck!
EDIT- if you're going to use 500+watt subs, and that box is one big chamber I'd highly suggest adding a piece of 2x4 between the front and rear wall to brace it. Make a nice tight fit and only glue will do.

Last edited by audio1der; 04-03-2012 at 11:08 PM.
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Old 04-04-2012, 04:43 AM
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For best acoustic results, scrap that box and start fresh. Looks like particle board, no internal bracing, holes that need plugging, a pair of ports that are likely way too small, etc... lots of issues. If you don't want to scrap that box, I'd think about joining both the rectangular tweeter horn hole and the circular port hole on the front to form one large rectangular port - and widen it a bit to prevent aperiodic loading from a large aspect ratio port.

Here's a good online calculator for your box planning/tuning: http://www.linearteam.dk/default.aspx?pageid=newdriver
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Old 04-04-2012, 10:21 AM
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Originally Posted by audio1der View Post
The holes on the side(s) are for cup terminals, so the speaker wire doesn't pass through the wood. You can buy them anywhere.
The rectangular holes on the front are for crappy horn tweeters. Seal those holes up using wood, good glue and a couple screws.
The round holes on the front are for ports. Figure out what the internal volume of the box is; if there is a divider in the middle so that each side it its own chamber, be aware of that. Figure out what frequency you want to tune your box to, and using any online port calculator, plug in your numbers to figure out what length of pipe to buy (obviously either buy the same diameter as the ex. holes, or enlarge the holes and buy appropriate diameter pvc).
Many of us tune around 36Hz-40Hz but thats a personal decision.
Good luck!
EDIT- if you're going to use 500+watt subs, and that box is one big chamber I'd highly suggest adding a piece of 2x4 between the front and rear wall to brace it. Make a nice tight fit and only glue will do.
Ok thanks for the info ive been scouring the internet trying to figure what the hell those holes were for lol....and there is a partition in the middle between the two subs so ill figure out the volume of each side sometime today and as for tuning i read in the specs for my subs that 30hz is the best tuning frequency so ill try for that and as for the pipe it self do i just seal it on the inside with some good glue as well?

For best acoustic results, scrap that box and start fresh. Looks like particle board, no internal bracing, holes that need plugging, a pair of ports that are likely way too small, etc... lots of issues. If you don't want to scrap that box, I'd think about joining both the rectangular tweeter horn hole and the circular port hole on the front to form one large rectangular port - and widen it a bit to prevent aperiodic loading from a large aspect ratio port.
I would scrap the box but im trying to go for cost effectiveness lol it is MDF though and it does have one internal brace and i agree on ehundred persent that it may turn out to be more work than its worth but im going to try first and for the large rectangular port what would i use as a port insert?
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Old 04-04-2012, 01:40 PM
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If you use round PVC it should be a tight enough fit that once you glue the outer circumference where it meets the MDF, thats all it should need. Keep in mind you can always have port sticking out of the box if length dictates, or you need that extra internal volume which the port would occupy, for the subs. FYI the cheapest, easiest PVC to buy is often thin-wall drain pipe. A 10', 4" pipe is $10, versus a 3' section of normal PVc which is $20.
If you go rectangular port you'll have to build them. More port area is always a good thing, but it will be more difficult.
Either way, make sure the inside is well sealed; some $2 sealant may be a great investment.
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Old 04-04-2012, 02:27 PM
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Honestly, a random size box with random size vents - I would plug them and try it sealed.
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Old 04-04-2012, 02:54 PM
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well either way if i go ported or sealed how long should i let the glue or silicon sit for before trying out the subs?
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Old 04-04-2012, 02:56 PM
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Originally Posted by Mikezord View Post
I would scrap the box but im trying to go for cost effectiveness lol it is MDF though and it does have one internal brace and i agree on ehundred persent that it may turn out to be more work than its worth but im going to try first and for the large rectangular port what would i use as a port insert?
You should use some MDF for the rectangular port.

A new box really will provide better results. Try designing one for your sub before you go working on this project. The difference in cost is minimal as a sheet of 3/4" MDF to start a new box entirely is not much more than a few planks of MDF to build your port.
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Old 04-04-2012, 03:01 PM
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Originally Posted by Mikezord View Post
well either way if i go ported or sealed how long should i let the glue or silicon sit for before trying out the subs?
At least two days clamped. Let it fully cure before you start flexing it.
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