TheMonolith2001 Posted September 10, 2012 Report Share Posted September 10, 2012 Building a box is way more complicated than I initially thought. I need some serious help! Using the calculators at the12volt and hometheatershack as well as Torres box calculator I have come up with a design I THINK works, but im reading i'm supposed to have 10-16 cubic inches of port per cubic foot of box which I am nowhere close to even though the box volume and port tuning is right. This seems like a HUGE port to me but maybe im following bad advice because there seems to be conflicting opinions on how much port you should have. Every time I get it to that much port the tuning is way off! I'm shooting for 8 cubic foot box with 28hz tuning. Here is what I have so far on my sub up port back design. Box size: 40w X 19 H X 24 D with a thickness of .75 inches. This gets me to 8.77 cubic feet. Port: Here is where I run into more trouble, when I calculate my port size, am I supposed to enter the volume BEFORE or AFTER including the port/bracer? Just using the 8.77 figure I come up with 16.5 inches wide by 3 inches tall with a port length of 13.6 inches. This is for a slot port if that wasn't already obvious and it doesnt HAVE to go around a corner right? a straight piece is what this would be. Port displacement ends up being 0.38958 cubic feet. Bracer: This looks like one of the bracers from the hometheatershack calculator ( http://www.hometheatershack.com/forums/enclosure-volume-calculator/ ) with rectangular cutouts. There are two cutouts. This measures 37.5 W X 17.5 H. The two cutouts are 13 X 12. This will brace it one way around while I will brace the other side with a threaded metal rod and bolts (which I figure is small enough to not bother calculathing displacement for) and sealing both sides with silicon or something. I am making it this way so it takes up just the right amount of room. It takes up 0.1494 cubic feet. Driver: Takes up .24 cubic feet, cant do anything about that number. Net Volume: I take my 8.77 cube box, subtract displacement of bracer, driver, and port and I end up with 7.99 cubic feet. I dont think I'm going to get much closer than that. This also gets me my 28hz tuning. (Torres Box Calculator seems slightly off, telling me its 7.78 after displacement with 29.72hz tuning if I lengthen the port to 16.5 inches however I get 27.97hz tuning which is again close enough this is going to screw up my port displacement however and I have to rethink some other aspects. I think this is because I'm using external measurements and Torres wants internal.) Does this all make sense? Is there a simpler way to do this? Am I doing anything obviously wrong? It seems to make sense to me but after being at this for the amount of time I have been I can no longer concentrate. I just want to make sure everything is absolutely going to fit before I order! Thanks alot! Link to comment Share on other sites More sharing options...
Joe X Posted September 10, 2012 Report Share Posted September 10, 2012 Post your maximum dimensions for a box, amp and vehicle models and type of music you listen to, if you have any electrical upgrades mention that too. Link to comment Share on other sites More sharing options...
TheMonolith2001 Posted September 11, 2012 Author Report Share Posted September 11, 2012 maximum dimensions are 41 W (MAYBE 42) X 24 D X 22 ish H (The higher I go the more it blocks my rear window, Ill go as high as I need to but if i can keep it around 18-20 that would be ideal.) Amp is now a Kicker ZR1000, Vehicle is a Jeep Cherokee Sport (XJ, not Grand Cherokee), I listen to just about everything but if sound type is focused slightly towards heavy bass music thats not a bad thing, Electrical upgrades to be done are big 3 of course, HO alt (270 amp mechman), and probably a Kinetik battery but I haven't researched enough to decide, I can say for sure at least some type of upgraded battery. If there is something else I should do let me know and im probably all for it. Link to comment Share on other sites More sharing options...
Joe X Posted September 11, 2012 Report Share Posted September 11, 2012 Ok so here is a suggestion on rated power and n your dims: Enclosure Specifications: Fb = 28 Hz Vb = 8 ft^3 External Height = 22.75 in External Width = 41.5 in External Depth = 24 in Port Width = 5 3/8 in Cut Sheet List: * All Dimensions in Inches. * Wood Thickness is 3/4 for all Parts. External Enclosure Parts: 2 x Top & Bottom (3 parts) = 41 1/2 x 24 Left & Right Sides = Side 1 = 22 1/2 x 20 1/2 Side 2 = 23 1/4 x 20 1/2 Front = 35 3/8 x 20 1/2 Back = 41 1/2 x 20 1/2 Folded Port Internal Assembly Parts: Front to Back = 17 1/8 x 20 1/2 Extension = 14 x 20 1/2 Assembly guide (generic dimensions): This is a SQ aimed tuning so as said it won't get overwhelmingly loud, just nice and low. Link to comment Share on other sites More sharing options...
TheMonolith2001 Posted September 11, 2012 Author Report Share Posted September 11, 2012 Holy crap that's awesome! So if I'm reading this right this is 7 cubes before displacement with a tuning of 33hz? Does that mean my goal of 8 cubes/28hz isn't possible? Link to comment Share on other sites More sharing options...
Joe X Posted September 11, 2012 Report Share Posted September 11, 2012 Holy crap that's awesome! So if I'm reading this right this is 7 cubes before displacement with a tuning of 33hz? Does that mean my goal of 8 cubes/28hz isn't possible? Right unless you increase your dims a bit, also pick the dual 2 ohm version of the sub for that amp. Link to comment Share on other sites More sharing options...
TheMonolith2001 Posted September 12, 2012 Author Report Share Posted September 12, 2012 yeah that's what I was planning on doing. How much would I have to increase my dims? It seems like 28hz tuning is the way to go with these subs so maybe I should go with the 15 instead? EDIT: Or just go BL and use the box design you have given me, isn't 33hz what is typically recommended for the BL? I haven't looked into it as much. EDIT2: What program did you use to make that? Id like to play around with it to see what I have to do to make this Q18 work! Link to comment Share on other sites More sharing options...
Joe X Posted September 12, 2012 Report Share Posted September 12, 2012 You could reach your spec on these dims: External Height = 22 in External Width = 41 in External Depth = 26.25 in On your second question, I have seen this sub tuned to different frequencies so... On your third question, Torres does the same, but calculators just crunch numbers, don't tell you what you should do. Link to comment Share on other sites More sharing options...
TheMonolith2001 Posted September 12, 2012 Author Report Share Posted September 12, 2012 hmm after some re-measuring and sitting in my car it seems I could live with: External Height = 23.25 in External Width = 42 in External Depth = 24 in since that should amount to the same area that would work right? I can go higher if I need to but 42 is definitely the absolute max on width. as far as depth goes I might have another inch or two but that messes up my amp mounting plans. Link to comment Share on other sites More sharing options...
TheMonolith2001 Posted September 12, 2012 Author Report Share Posted September 12, 2012 Did some messing around in WinISD, and came up with the following: http://i.imgur.com/F4lzp.png It seems like the Q doesn't really get all that much louder at lower frequencies than the bl when comparing a 28hz 8 cube box to a 33hz 7 cube box until you get into REALLY low frequencies. Does this look correct or am I missing something? Link to comment Share on other sites More sharing options...
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