g2shuck Posted December 2, 2013 Report Share Posted December 2, 2013 I keep getting told to stay around 15 square inches of port for cubic feet which I have always done in the past, but is there not a formula to find port area based off sd and xmax? I am doing a wall with two level 6 m3 18s and 15 inches per foot would be around 200 sqaure inches of port for 12 cubes net. To me that just seams really low for two 18 with 32.5mm xmax and 1217cm² sd. Quote 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...
scooter99 Posted December 2, 2013 Report Share Posted December 2, 2013 In for the answer to this as well. I'm always trying to figure out what the sq in of port is based off of. Quote Facebook Page: S99Creations 2006 F250 Lariat Build Link to comment Share on other sites More sharing options...
CleanSierra Posted December 2, 2013 Report Share Posted December 2, 2013 There's your formula: http://www.carstereo.com/help/Articles.cfm?id=31 You can get away with less in a vehicle cabin but I try not to cut from the suggested minimum number TOO much. The 15" per foot is a rule of thumb for MOST drivers. However, port area isn't driven by how much airspace you have. A given sub, just for generic example an 18" sub, will need the same amount of of port if it's in a 5 cube as it would if it's in a 6 cube box. Desired tuning, Xmax, and cone area is what should be being used to determine port area. Quote 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...
CleanSierra Posted December 2, 2013 Report Share Posted December 2, 2013 Also if you click the FORMULA, it will redirect you to the page where the hard formula is to actually do the calculation by hand. I've done it and it checks out. Quote 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...
g2shuck Posted December 2, 2013 Author Report Share Posted December 2, 2013 There's your formula: http://www.carstereo.com/help/Articles.cfm?id=31 You can get away with less in a vehicle cabin but I try not to cut from the suggested minimum number TOO much. The 15" per foot is a rule of thumb for MOST drivers. However, port area isn't driven by how much airspace you have. A given sub, just for generic example an 18" sub, will need the same amount of of port if it's in a 5 cube as it would if it's in a 6 cube box. Desired tuning, Xmax, and cone area is what should be being used to determine port area. I knew that is was not box dependent which is why I was not happy to keep getting told 15 per foot. According to that claculator I need 300 inches for the two 18s with 32.5mm xmax tuned to 30 hz. WAY more than 15 per foot lol. Quote 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...
scooter99 Posted December 2, 2013 Report Share Posted December 2, 2013 Thanks for posting that Sierra! I'll go learn some stuff now! I appreciate that. Quote Facebook Page: S99Creations 2006 F250 Lariat Build Link to comment Share on other sites More sharing options...
iwannabeloud Posted December 2, 2013 Report Share Posted December 2, 2013 Also if you click the FORMULA, it will redirect you to the page where the hard formula is to actually do the calculation by hand. I've done it and it checks out. That formula recommends 164.51 for one level 6 18 at 33hz. Is that correct? That seems like lot of port for one. Quote I don't put images in my signature to let people know I mean business. Link to comment Share on other sites More sharing options...
g2shuck Posted December 2, 2013 Author Report Share Posted December 2, 2013 I will probably end up with around 250 square inches of port for my 13 cubes net. So around 20 incher per foot. Quote 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...
n8ball2013 Posted December 2, 2013 Report Share Posted December 2, 2013 Now ive said this before. I want to see one of those boxes with all that port on a termlab. Over a spectrum of frquencies. Just because there is a formula out there doesnt mean its right. I dont care how good someone says it is. If it falls on its face jn the output category sounding good just means not loud and from my own experience and all the people ive dealt with and worked with who have experinented with this kind of thing there is a decrease in output from too much port area Quote 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...
CleanSierra Posted December 2, 2013 Report Share Posted December 2, 2013 But what determines TOO much port area? A TL, ears? I agree that less port area can be used since sound waves can't even fully generate in the vehicle cabin. Avoiding peaky response and mouse are the two biggest things. When you REALLY look at the purpose of the vented enclosure in general, the idea is not to BE flat responding if we want to get technical. Its to have a bump in output around tuning frequency and then to rollloff above and below tuning. Quote 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...
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