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Custom Box for Truck; Size constraints - Help & Tips needed
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<blockquote data-quote="Doxquzme" data-source="post: 8867750" data-attributes="member: 689267"><p><em><strong>“I am pretty sure that when the MM was connected to just one + and one - port on the sub that it was reading 2 OHMs with nothing else connected.”</strong></em></p><p></p><p>What does the box and the literature sheet say? The massive website only list the one shallow mount sub in a dual 4 ohm configuration.</p><p></p><p><em><strong>“I am redesigning the box as well (well resizing really) as I learned he wants to be able to put his center console up so someone can sit in the middle, and that drastically reduces the space behind the seats. There are also some sort of clips installed on the back wall throughout that add a bit of depth as well so I need to take that into consideration.”</strong></em></p><p></p><p>As long as you are close to those ideal internal volumes that we’re shooting for, that is the goal. 3.62 is on the large size. need to get it down to around 3.12 – 3.25 gross. 3.6 is too large.</p><p></p><p>I hate to do this but I’m going to switch gears on you. Let’s consider a port that is rectangle and uses the existing structures front baffle and rear wall.</p><p></p><p>Taking the internal depth of the box, internally, you have 7.25” instead of using the two round ports; let’s design a slot port up the middle. It will need to be 7.25”D x 3.25”W x 12.875”L.</p><p></p><p>Make the box get to that golden 3.12 – 3.25 cubic feet. We can add extra pieces of wood internally on the sides, or as braces, etc, we need to get the box to that size., This rectangle port will run up the middle and vent out the top as up and out the top seems the easiest and it allows the port to bounce off the roof, give you a little cabin gain. , here is an example (not to scale, just for orientation sake) Let's stick to the port exiting out the top. In the middle up out the top.</p><p></p><p></p><p>[ATTACH=full]55883[/ATTACH]</p><p></p><p></p><p>This does two things. it simplifies the build ( as all you have to do is cut the hole out the top, cut two pieces to leng and glue them in) and the port now does dual duty as a very strong brace up the middle. In this enclosure, the size is important and the port dimensions need to be as stated. That port in a 3.12-3.25 box gets you to that 33-35 hZ tuning point. That's close to or slightly above the resonant frequency of the driver. With the power that you are givin g this box, that port should be fine. Porting out out the top eliminates obstruction concerns, etc. I modeled it and the vent velocity is marginal.</p><p></p><p>In this design, I've already taken into consideration the woofer and port displacement, no need to overthink it. I would add corner bracing like this:</p><p></p><p>[ATTACH=full]55884[/ATTACH]</p><p></p><p>Anywhere you can, it adds rigidity. It's going to be a fairly stout box with that port running up the middle, no need to worry to much about the minimal displacement adding the corner braces will deduct from the volume, it's insignificant.</p><p></p><p>Stick to this design, it's a simple, effective, no compromise design - win/win</p><p></p><p><em><strong>"And finally, when building the walls, is there a particular order that would be better suited to put it together."</strong></em></p><p></p><p>I would build so that the front baffle and the rear baffle are over the sides, not within them. - the opposite way you have your cad drawing.</p></blockquote><p></p>
[QUOTE="Doxquzme, post: 8867750, member: 689267"] [I][B]“I am pretty sure that when the MM was connected to just one + and one - port on the sub that it was reading 2 OHMs with nothing else connected.”[/B][/I] What does the box and the literature sheet say? The massive website only list the one shallow mount sub in a dual 4 ohm configuration. [I][B]“I am redesigning the box as well (well resizing really) as I learned he wants to be able to put his center console up so someone can sit in the middle, and that drastically reduces the space behind the seats. There are also some sort of clips installed on the back wall throughout that add a bit of depth as well so I need to take that into consideration.”[/B][/I] As long as you are close to those ideal internal volumes that we’re shooting for, that is the goal. 3.62 is on the large size. need to get it down to around 3.12 – 3.25 gross. 3.6 is too large. I hate to do this but I’m going to switch gears on you. Let’s consider a port that is rectangle and uses the existing structures front baffle and rear wall. Taking the internal depth of the box, internally, you have 7.25” instead of using the two round ports; let’s design a slot port up the middle. It will need to be 7.25”D x 3.25”W x 12.875”L. Make the box get to that golden 3.12 – 3.25 cubic feet. We can add extra pieces of wood internally on the sides, or as braces, etc, we need to get the box to that size., This rectangle port will run up the middle and vent out the top as up and out the top seems the easiest and it allows the port to bounce off the roof, give you a little cabin gain. , here is an example (not to scale, just for orientation sake) Let's stick to the port exiting out the top. In the middle up out the top. [ATTACH type="full" width="729px" alt="1704344032921.png"]55883[/ATTACH] This does two things. it simplifies the build ( as all you have to do is cut the hole out the top, cut two pieces to leng and glue them in) and the port now does dual duty as a very strong brace up the middle. In this enclosure, the size is important and the port dimensions need to be as stated. That port in a 3.12-3.25 box gets you to that 33-35 hZ tuning point. That's close to or slightly above the resonant frequency of the driver. With the power that you are givin g this box, that port should be fine. Porting out out the top eliminates obstruction concerns, etc. I modeled it and the vent velocity is marginal. In this design, I've already taken into consideration the woofer and port displacement, no need to overthink it. I would add corner bracing like this: [ATTACH type="full" width="571px" alt="1704345147480.png"]55884[/ATTACH] Anywhere you can, it adds rigidity. It's going to be a fairly stout box with that port running up the middle, no need to worry to much about the minimal displacement adding the corner braces will deduct from the volume, it's insignificant. Stick to this design, it's a simple, effective, no compromise design - win/win [I][B]"And finally, when building the walls, is there a particular order that would be better suited to put it together."[/B][/I] I would build so that the front baffle and the rear baffle are over the sides, not within them. - the opposite way you have your cad drawing. [/QUOTE]
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