CleanSierra Posted November 8, 2013 Report Share Posted November 8, 2013 So make a compromise of window viewing pleasure for listening pleasure, otherwise 15s are you option. Or like was mentioned, 18s in a different brand. A sufficient port will eat more than 3 feet alone. My 220" port that is double walled and 18" deep displaces 3 cubes. Im not the one you want to try to troll. Just a fyi for you. Link to comment Share on other sites More sharing options...
Fuzzy336 Posted November 8, 2013 Author Report Share Posted November 8, 2013 so one more idea to throw around... If I went from my original idea of 25" tall to 28" tall, by 49" wide, and 36" deep, my gross interal air space will be 24.04 cubic feet. I will have 5 inches from the back of the box to the back hatch, so I could do my port 47" wide (the width of the entire box except the outer walls) by 5 inches tall, giving me 235 square inches of port area, and if i made that 19" deep, that would make my port tuned to 33.3 hz, the resonance of the Fi Bl 18's, and the port displacement would be 3 cubic feet. the subs will displace 1.04 cubic feet, so I would be looking at: dimensions: 49"x28"x36" Gross air space: 24.04 cubic feet port dimensions: 47"x5"x19" port square area: 235 square inches port displacement: 3 cubic foot port tune: 33 hz (almost the exact same as the subs resonance level) subs displacement: 1.04 cubic feet So knowing all off that, my net air space would be 20 cubic foot before any bracing (24.04-3= 21.04, then 21.04-1.04=20) So if I was (completely hypothetically speaking) to still have 20 cubic foot of airspace without any bracing, the 235 square inches divided by 20 cubic foot would be 11.75 square inches of port area per cubic foot of airspace and 5 cubic foot of airspace per sub (once again before any bracing). Now if I was to (hypothetically speaking again) use 2 cubic feet of airspace in bracing, then the 235 square inches divided by 18 cubic foot would be 13.05 square inches per cubic foot of airspace and 4.5 cubic foot of airspace per sub. From what everyone has been telling me, does that size port seem realistic as to what I want to build? and considering that the subs Fs is 33.2 Hz, my box design is 33.3 Hz and my Tahoes resonance is somewhere between 38-42 Hz, do you think i should tune slightly higher or lower as this will mainly be a daily driver and I want to hit a decent range of notes/slam the lows/still hit decent numbers on the termlab? When I get the chance to use the formula on the other thread i will post up what it says but does this current idea not take everything i've been told into consideration to make this build the best it can be? Let me know what everyone thinks of the new design, thanks again for all the help! My Youtube Channel Trying to guess the SPL of a system with out a meter is like trying to guess how much air pressure is in a compressor tank just by letting some of the air out. ...Seems like 90 psi... Link to comment Share on other sites More sharing options...
rockFord_Expedition Posted November 8, 2013 Report Share Posted November 8, 2013 Looking much better. A tip to save cubes, use threaded rod for bracing. You can squeeze in a lot of support and sacrifice next to no air space. Old School/New School RF Build March 2015 SOTM Winner How to crimp large wire Link to comment Share on other sites More sharing options...
RMac18 Posted November 8, 2013 Report Share Posted November 8, 2013 Another idea you can think about is inverting the subs to save airspace inside the box. However I dunno if you want to invert them either way, plus it will place them on top of the box and above the window line and in plain view from outside the vehicle. Just a thought though. Link to comment Share on other sites More sharing options...
n8ball2013 Posted November 8, 2013 Report Share Posted November 8, 2013 Then he can't see through the woofers THERE IS NO BUILD LOG! 1998 Chevy Silverado ext cab Alpine CDA-9887 4 Team Fi 15s 2 Ampere Audio TFE 8.0 2 Ampere Audio 150.4 3 Digital Designs CS6.5 component sets Dual Mechman 370XP Elite alternators inbound! 8 XS Power d3400 6 XS power d680 Second Skin Stinger Tsunami Wiring Sky High A Real Voltmeter not a piece of shit stinger. Link to comment Share on other sites More sharing options...
g2shuck Posted November 8, 2013 Report Share Posted November 8, 2013 IMHO you need closer to 28-30 cubes gross to get the proper port area and still have the proper net volume. I would be shooting for around 300 inches of port and 24 cubes net for 4 18s. 2000 Toyota Camry With Sealed Off Trunk Sky High OFC Wiring DC Power 270 XP Alt AQ 2200 Sub Amp Two DC Level 4 m2 12s 80 Mil Murdetmat Gathering Parts For Wall Build. Team DC Audio 2014 Member Link to comment Share on other sites More sharing options...
Fuzzy336 Posted November 9, 2013 Author Report Share Posted November 9, 2013 I've got 4 questions... 1) So by building the box 28" tall the box will be 3" shorter than the top of the backseat headrest, and 14" from the ceiling of the truck, is that ok? 2) What is the difference be between putting the box 5 inches from the hatch and have it firing back against the hatch or building the box all the way to the hatch and having the port on the top of the box but at the very back firing upwards? Which of the 2 would be better and why? 3) is tuning the box to 33.3 Hz when the subs resonance is 33.2 Hz a good or bad idea, if it's a bad one would you recommend tuning higher or lower? It's going to be a daily driver yet I still want to slam the lows and be able to put up good numbers at a competition. 4) if I use the metal rods for bracing by putting a plate on each end with screw holes to mount it, how many of those do you think I would need? Like how many for the x, y and z axis? Thanks for all of the help everyone! I'm sure this is going to turn out great! My Youtube Channel Trying to guess the SPL of a system with out a meter is like trying to guess how much air pressure is in a compressor tank just by letting some of the air out. ...Seems like 90 psi... Link to comment Share on other sites More sharing options...
rockFord_Expedition Posted November 9, 2013 Report Share Posted November 9, 2013 I've got 4 questions... 1) So by building the box 28" tall the box will be 3" shorter than the top of the backseat headrest, and 14" from the ceiling of the truck, is that ok? Should be fine. Just deaden your roof really well. 2) What is the difference be between putting the box 5 inches from the hatch and have it firing back against the hatch or building the box all the way to the hatch and having the port on the top of the box but at the very back firing upwards? Which of the 2 would be better and why? In most full size SUV's subs up port back works best on the meter. Don't know the science behind it, it just does. There isn't really a one size fits all approach though. 3) is tuning the box to 33.3 Hz when the subs resonance is 33.2 Hz a good or bad idea, if it's a bad one would you recommend tuning higher or lower? It's going to be a daily driver yet I still want to slam the lows and be able to put up good numbers at a competition. Your enclosure will be considered a wall in competitions, just a heads up.. I have a feeling you will meter higher with a slightly higher tune, but I don't know those subs that well so I could be wrong. 4) if I use the metal rods for bracing by putting a plate on each end with screw holes to mount it, how many of those do you think I would need? Like how many for the x, y and z axis? 2 x 1" threaded rod on top to bottom (the weight of the subs will help hold it steady). 4 x Side to side. and 4 front to back is what I would recommend. Thanks for all of the help everyone! I'm sure this is going to turn out great! Old School/New School RF Build March 2015 SOTM Winner How to crimp large wire Link to comment Share on other sites More sharing options...
Fuzzy336 Posted November 9, 2013 Author Report Share Posted November 9, 2013 Thanks for the fast reply! If I do 2 top to bottom, should they both be from the ground to the top of the box, or should I have any from the top of the box to the top of the port? My Youtube Channel Trying to guess the SPL of a system with out a meter is like trying to guess how much air pressure is in a compressor tank just by letting some of the air out. ...Seems like 90 psi... Link to comment Share on other sites More sharing options...
rockFord_Expedition Posted November 9, 2013 Report Share Posted November 9, 2013 Thanks for the fast reply! If I do 2 top to bottom, should they both be from the ground to the top of the box, or should I have any from the top of the box to the top of the port? Is your port going to have 3 common walls with the outside of the enclosure? By looking at your dimensions I am guessing the bottom of the enclosure is also the bottom of the port. You have 2 choices, and unless you metered it both ways it would be really hard to tell. If you divide your internal front to back measurement by 3 you get 11 1/3" unless I misunderstood something. Structure wise, this will give you the most rigidness and support if you spaced one 11 1/3" from the back wall and the other 11 1/3" from the front wall. They would each be 11 1/3" from each other. With this you will encounter having bracing near your inside port opening. Some will tell you don't do it because of port turbulence etc. Since your port is 19" front to back, this accounts for more than half of the depth. You could get away with placing them both on top of the port. Your call Old School/New School RF Build March 2015 SOTM Winner How to crimp large wire Link to comment Share on other sites More sharing options...
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