wood thickness

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=121212
Printed Date: May 03, 2024 at 1:02 AM

Topic: wood thickness

Posted By: stang351w
Subject: wood thickness
Date Posted: April 07, 2010 at 8:08 PM

i know this is prob going to be one of those stupid questions but i gotta figure it out befor i start the build lol. i'm putting a RE XXX15" sub backed by a 1500 watt MTX amp (all customer supplied so i couldn't sell a larger amp) but i'm debating on building the with 3/4" MDF or 1" MDF. keep in mind i will be braceing it internally as well. the box is going to be 4 cu/ft (counting for the sub and port displacement). if i was going sealed i would do 1" but where it's ported i'm on the edge...what do you guys think?

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Tri County KustomZ
certified installer

Replies:

Posted By: anonymous1
Date Posted: April 07, 2010 at 8:36 PM

https://www.the12volt.com/installbay/forum_posts.asp~TID~74592~PN~1

Posted By: stevdart
Date Posted: April 07, 2010 at 11:58 PM

Looking at the size of the enclosure which at 4 cu ft is pretty large, I tend more toward supersizing the wall thickness. Things you should look at are the stress point areas of large baffle expanses.

posted_image

The spots marked in yellow are the weakest points on those baffles. The face baffle is the critical component because it has to provide the footing for the woofer beast while at the same time have a large hole cut out of it. Saying, there is less of this baffle due to the cutout, and more stress applied because the woofer is attached to it.

Depending upon what materials I have on hand, I would tend to go double thickness on the face baffle for this build. Double 3/4 or double 1", whatever you have. With adequate bracing at the stress areas, single ply 1" for the rest of the box. If you have 3/4", look into shortening the expanse areas between braces. Thicker is always better in the large subwoofer enclosure build.

And note: there isn't a difference because it's a ported box rather than a sealed. The function remains the same, and loss of dynamic sound due to wall undulation (stress) applies with a ported box just as much as with a sealed.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: haemphyst
Date Posted: April 08, 2010 at 10:56 PM

I agree with stevdart, but I also want to mention that you are stressing wall thickness in the wrong direction.

The minimum and maximum pressures in a VENTED enclosure are SIGNIFICANTLY higher than in a sealed enclosure. Knowing this, which enclosure will use the 1" MDF? *I'm* using 1", and saving the ¾" for the sealed box.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: stang351w
Date Posted: April 09, 2010 at 5:34 AM

thanks for all the info guys.. i've got a sheet of 1" MDF delivered yesterday, now it's time to make this things pound. the 15" RE is going into a 4cu/ft box tuned to 30HZ and being run of a 1500 watt RMS MTX amp (1 ohm mono) into a olds alero. the original design was to have the sub faceing the back seats and ported through the rear shelf and the back of the trunk would of been sealed off so no real amount of sound got back there but the customer decided to change it and now it's going to be facing to the back of the trunk. pics will come after today

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Tri County KustomZ
certified installer

Posted By: stang351w
Date Posted: April 09, 2010 at 6:36 PM

well..just to keep the threads low...thought i'd upload a pic of the install.

posted_image

sorry for the fuzzy pic...but it's a 1500 watt MTX amp, power acoustik 10 farad cap and a 15" RE XXX sub sitting in the back of an olds alero. the center peice where the cap is sitting will be covered with a tan vynal to match the interior of the car.

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Tri County KustomZ
certified installer