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Enclosure Design & Construction
Non-standard custom ported or bandpass box design questions: 1x CT Sounds TROPO 18 D4
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<blockquote data-quote="technotic" data-source="post: 8822644" data-attributes="member: 687269"><p>I've got just about every measurement for my trunk now <img class="smilie smilie--emoji" loading="lazy" alt="😎" title="😎" src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f60e.png" /> it's currently emptied with all panels removed including the trim (not the rear deck). All wires, latch, light, and basically anything that isn't the actual body, is masked, including having pushed the seats down a little to put a drop cloth plastic sheet over the opening, I used vapor barrier tape for that area.</p><p></p><p>I started the first step I wanted to do which is coating the inside of my trunk with 3m pro rubberized undercoating spray. I was dumb and only bought one can at first, just got a couple more today, will finish that tomorrow. Also sprayed the top inside of my trunk lid (also replaced my lift supports because the old ones were shot) but I'm not sure if I wanna do the trunk rear or just use siless on it.</p><p></p><p>I got a big bag of poly-fil to stuff wherever I need to do I don't have rattles. I picked up some siless vibro 80 mil (foiled). 36sq ft. The idea is to deal with any transient waves I haven't messed with the trim in the cab but I plan to take the door panels off and stick some siless and poly-fil in there too. I read about a 25% rule, basically diminishing returns beyond 25% coverage of an area, placed properly of course (is 3 pads enough? I need to finish looking up the right placement for the siless). I'm looking to get some road/outside noise cut down and also smooth any sharp edges of my sound.</p><p></p><p>I also picked up a quart of Bondo polyester resin and an 8sq ft sheet of Bondo fiberglass. I plan to use my wheel well and place the speaker above it, facing up. I'm trying to decide if I should angle it at all or go for flat. I also picked up 2x 4ftx4ft 3/4 inch voidless plywood. My wheel well is 23 inches wide and squares against the rear of the car while the further point is 23 inches. It's 8 inches deep. I was thinking of cutting a piece of the plywood to sit flat on the bottom.</p><p></p><p>Since I'm building it in the car, what should I use to fill voids between that piece of plywood and the coating underneath? I have 2 cans of red Good Stuff expanding foam. I also intend to use the stock spare tire threading hole to secure it down. I would like to be able to remove it if necessary without TOO much hassle so I don't want to bond the plywood to the body unless you think I really should. I also planned on cutting plywood walls. I figured a diagonal on each side and then a flat across the top/far edge, but I'm still very open to changes on that. I was going to then foam the outer gaps and fiberglass the inside of that cavity. But would it be better to leave out the walls, or even the bottom piece as well, and just go for fiberglass inside the wheel well and then bring it up into wood on the bottom of the trunk? I'll try to post a sketch of what I'm envisioning. CT Sounds specs call for 6.5cbft tuned at 28hz with 40sqin port area for their SPL spec. I'm not specifically trying to do SPL but I figured the closer I stick to those specs, the better off I will be. I was thinking of calculating out the height I need to come up off the trunk bottom to meet those specs. Between the rear wheel wells and the back of the trunk is 10 inches on each side. That's the widest point at 50 inches. The wells jut inward about 10 inches I believe, and go up about the same. Just giving rough numbers on these, but I have the actual numbers written down. I'd like to balance the height up off the trunk bottom and the distance needed to go forward. I was thinking of doing a dual square port, with the port openings facing the cab, possibly coming above the wheel wells? I can angle cut the openings. Maybe I'm getting too far in over my head for this build, but would I benefit from using contours in the ports on the sides as compressors? That would allow a shorter port length I think? Or at least cut down on chuffing. I planned to cut the hole just a bit bigger than the sub edges, then cut the exact fit into a 2ftx2ft plywood board, use some sort of filler epoxy or liquid or foam spray between the 2x2 board and the main top board and screw it in using 2 inch spaces just outside the sub ring, from the bottom up so the screws are hidden, and also around the outer edge of the 2x2, with whatever looks right to cover the space between the inner and outer edges. I'd also put a couple in from the top down around the corners. This way I have a partial double baffle but also the sub sits recessed. I can put a piece of acoustically transparent fabric across the gap (like what's used on typical house speakers), possibly with Velcro on the sides so I can have it on or off. Keep dust and such from settling on the cone. I'm not sure what to line the inside of the enclosure with yet. I thought about vinyl floor tiles possibly. Or I could spray coat the inside. I don't know how thick I'd have to lay the fiberglass if I didn't use wood for the bottom side (original plan was to lay wood and then fiberglass over top of it for the bottom of the enclosure). using wood and foaming the gaps between the edges of the body and the enclosure would make the enclosure linear and more controllable and sound better maybe than fiberglassing onto the coating directly? So much to think about. </p><p></p><p>Oh. Are you familiar with pocket holes for carpentry work? I have a Kreg jig and plenty of proper pocket hole screws for 3/4 ply. Those are pretty damn sturdy joints. I can fill the holes. I do have hardwood plugs for them and can glue them in. I think it would be more sturdy than just screwing along the joints. I also need to plan out bracings and the port walls.</p><p></p><p>Maybe it's best if I sketch up what I had in mind and you can tell me if it's workable? Rather than asking someone to just design it for me. I don't need to over engineer it but I want it to look great and sound great. I can take constructive criticism that isn't insulting or rude, and I'm willing to accept as much help and input as you're willing to offer. I already have the plywood, the siless, the poly-fil, the undercoating spray, the expanding foam spray, vinyl tiles (don't know about using those), some neoprene (I can buy some additional if needed), the fiberglass mat and resin, and of course all the tools (jigsaw, circular saw, drills, fasteners, wood glue, silicon sealant tubes, etc). I have a router too but would be freehanding it and I need bits. But I have a couple rotary tools with plenty of attachments. I'd like to minimize additional purchases but if it's necessary, I will.</p><p></p><p>Anyway I appreciate your time and feedback.</p></blockquote><p></p>
[QUOTE="technotic, post: 8822644, member: 687269"] I've got just about every measurement for my trunk now 😎 it's currently emptied with all panels removed including the trim (not the rear deck). All wires, latch, light, and basically anything that isn't the actual body, is masked, including having pushed the seats down a little to put a drop cloth plastic sheet over the opening, I used vapor barrier tape for that area. I started the first step I wanted to do which is coating the inside of my trunk with 3m pro rubberized undercoating spray. I was dumb and only bought one can at first, just got a couple more today, will finish that tomorrow. Also sprayed the top inside of my trunk lid (also replaced my lift supports because the old ones were shot) but I'm not sure if I wanna do the trunk rear or just use siless on it. I got a big bag of poly-fil to stuff wherever I need to do I don't have rattles. I picked up some siless vibro 80 mil (foiled). 36sq ft. The idea is to deal with any transient waves I haven't messed with the trim in the cab but I plan to take the door panels off and stick some siless and poly-fil in there too. I read about a 25% rule, basically diminishing returns beyond 25% coverage of an area, placed properly of course (is 3 pads enough? I need to finish looking up the right placement for the siless). I'm looking to get some road/outside noise cut down and also smooth any sharp edges of my sound. I also picked up a quart of Bondo polyester resin and an 8sq ft sheet of Bondo fiberglass. I plan to use my wheel well and place the speaker above it, facing up. I'm trying to decide if I should angle it at all or go for flat. I also picked up 2x 4ftx4ft 3/4 inch voidless plywood. My wheel well is 23 inches wide and squares against the rear of the car while the further point is 23 inches. It's 8 inches deep. I was thinking of cutting a piece of the plywood to sit flat on the bottom. Since I'm building it in the car, what should I use to fill voids between that piece of plywood and the coating underneath? I have 2 cans of red Good Stuff expanding foam. I also intend to use the stock spare tire threading hole to secure it down. I would like to be able to remove it if necessary without TOO much hassle so I don't want to bond the plywood to the body unless you think I really should. I also planned on cutting plywood walls. I figured a diagonal on each side and then a flat across the top/far edge, but I'm still very open to changes on that. I was going to then foam the outer gaps and fiberglass the inside of that cavity. But would it be better to leave out the walls, or even the bottom piece as well, and just go for fiberglass inside the wheel well and then bring it up into wood on the bottom of the trunk? I'll try to post a sketch of what I'm envisioning. CT Sounds specs call for 6.5cbft tuned at 28hz with 40sqin port area for their SPL spec. I'm not specifically trying to do SPL but I figured the closer I stick to those specs, the better off I will be. I was thinking of calculating out the height I need to come up off the trunk bottom to meet those specs. Between the rear wheel wells and the back of the trunk is 10 inches on each side. That's the widest point at 50 inches. The wells jut inward about 10 inches I believe, and go up about the same. Just giving rough numbers on these, but I have the actual numbers written down. I'd like to balance the height up off the trunk bottom and the distance needed to go forward. I was thinking of doing a dual square port, with the port openings facing the cab, possibly coming above the wheel wells? I can angle cut the openings. Maybe I'm getting too far in over my head for this build, but would I benefit from using contours in the ports on the sides as compressors? That would allow a shorter port length I think? Or at least cut down on chuffing. I planned to cut the hole just a bit bigger than the sub edges, then cut the exact fit into a 2ftx2ft plywood board, use some sort of filler epoxy or liquid or foam spray between the 2x2 board and the main top board and screw it in using 2 inch spaces just outside the sub ring, from the bottom up so the screws are hidden, and also around the outer edge of the 2x2, with whatever looks right to cover the space between the inner and outer edges. I'd also put a couple in from the top down around the corners. This way I have a partial double baffle but also the sub sits recessed. I can put a piece of acoustically transparent fabric across the gap (like what's used on typical house speakers), possibly with Velcro on the sides so I can have it on or off. Keep dust and such from settling on the cone. I'm not sure what to line the inside of the enclosure with yet. I thought about vinyl floor tiles possibly. Or I could spray coat the inside. I don't know how thick I'd have to lay the fiberglass if I didn't use wood for the bottom side (original plan was to lay wood and then fiberglass over top of it for the bottom of the enclosure). using wood and foaming the gaps between the edges of the body and the enclosure would make the enclosure linear and more controllable and sound better maybe than fiberglassing onto the coating directly? So much to think about. Oh. Are you familiar with pocket holes for carpentry work? I have a Kreg jig and plenty of proper pocket hole screws for 3/4 ply. Those are pretty damn sturdy joints. I can fill the holes. I do have hardwood plugs for them and can glue them in. I think it would be more sturdy than just screwing along the joints. I also need to plan out bracings and the port walls. Maybe it's best if I sketch up what I had in mind and you can tell me if it's workable? Rather than asking someone to just design it for me. I don't need to over engineer it but I want it to look great and sound great. I can take constructive criticism that isn't insulting or rude, and I'm willing to accept as much help and input as you're willing to offer. I already have the plywood, the siless, the poly-fil, the undercoating spray, the expanding foam spray, vinyl tiles (don't know about using those), some neoprene (I can buy some additional if needed), the fiberglass mat and resin, and of course all the tools (jigsaw, circular saw, drills, fasteners, wood glue, silicon sealant tubes, etc). I have a router too but would be freehanding it and I need bits. But I have a couple rotary tools with plenty of attachments. I'd like to minimize additional purchases but if it's necessary, I will. Anyway I appreciate your time and feedback. [/QUOTE]
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Non-standard custom ported or bandpass box design questions: 1x CT Sounds TROPO 18 D4
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