Torres Posted January 20, 2011 Report Share Posted January 20, 2011 I just take how big the square that the angle makes is, in your case (not counting wood) is 6.5x16.5x46.5, figure that volume, divide by 2, then figure the volume of the entire box, as if it didnt have an angle, 35x46.5x24.5, and subtract. And to figure the wood you just subtract the size of the wood times 2 from all measurements. not quite that easy. sectioning off the squares is the easy part. doing the triangle part of the box with the angled wood is where the precision comes in. since the wood is at an angle, the measurement of where that meets the flat part of the box is not quite .75" thick, and depending on how much of an angle there is will depend on how thick the two corners are, changing the volume ever so slightly. keyword there is *slightly* tho. our measurements were very very close Quote Link to comment Share on other sites More sharing options...
Berto Posted January 21, 2011 Author Report Share Posted January 21, 2011 I just take how big the square that the angle makes is, in your case (not counting wood) is 6.5x16.5x46.5, figure that volume, divide by 2, then figure the volume of the entire box, as if it didnt have an angle, 35x46.5x24.5, and subtract. And to figure the wood you just subtract the size of the wood times 2 from all measurements. not quite that easy. sectioning off the squares is the easy part. doing the triangle part of the box with the angled wood is where the precision comes in. since the wood is at an angle, the measurement of where that meets the flat part of the box is not quite .75" thick, and depending on how much of an angle there is will depend on how thick the two corners are, changing the volume ever so slightly. keyword there is *slightly* tho. our measurements were very very close I think I kind if get that, but I'll have to mess with some numbers to make sure. I have another question. I was told to get about 100sq" of port, is it really as easy as a 5" x 20" port opening? Quote TEAM FLEX ISSUES Car: 1985 Oldsmobile Delta 88 Royal 24" Rims HU: 7" Carputer, Planet Audio EQ, iPhone. Coax: T3 Audio 4" speakers Subs: 2x 18" T3 Audio TSNS (walled) Sub Amp: DC 9k SOON TO COME T3 Audio 6x9s MB Quarts 6.5" comp set MAYBE ADDED 2nd DC 9k Link to comment Share on other sites More sharing options...
Torres Posted January 21, 2011 Report Share Posted January 21, 2011 yep. surface area of the port is port area. 5 x 20, 4 x 25, 8 x 12.5, etc. and not to contradict what ed said...but a 16 cube wall...with only 100 sq inches of port? that's 6.25 sq inches per foot. sounds awfully tiny to me. you sure you read what he meant right? just curious in case you overlooked something Quote Link to comment Share on other sites More sharing options...
Berto Posted January 21, 2011 Author Report Share Posted January 21, 2011 (edited) yep. surface area of the port is port area. 5 x 20, 4 x 25, 8 x 12.5, etc. and not to contradict what ed said...but a 16 cube wall...with only 100 sq inches of port? that's 6.25 sq inches per foot. sounds awfully tiny to me. you sure you read what he meant right? just curious in case you overlooked something I think that's what he said. I'm not 100% sure though. I remember reading about a "rule of thumb" when calculating port area but I forgot where. It was a "x amount of port per cubic foot" or something like that. EDIT: I found where I saw the 100sq" of port and it wasn't Ed, it was someone else and they were only talking about 1 18 not 2 of them. I FAIL. =[ what would you suggest for my port? Edited January 21, 2011 by Berto Quote TEAM FLEX ISSUES Car: 1985 Oldsmobile Delta 88 Royal 24" Rims HU: 7" Carputer, Planet Audio EQ, iPhone. Coax: T3 Audio 4" speakers Subs: 2x 18" T3 Audio TSNS (walled) Sub Amp: DC 9k SOON TO COME T3 Audio 6x9s MB Quarts 6.5" comp set MAYBE ADDED 2nd DC 9k Link to comment Share on other sites More sharing options...
Decaf Posted January 21, 2011 Report Share Posted January 21, 2011 200sqin = 12.5sqin per cuft in ur case Quote Link to comment Share on other sites More sharing options...
bkolfo4 Posted January 21, 2011 Report Share Posted January 21, 2011 Why do people continue to worry about how much port area there is per cubic foot???? They are NOT related! Quote Current system: 1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s Previous systems: 2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz. 1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz. Link to comment Share on other sites More sharing options...
Decaf Posted January 21, 2011 Report Share Posted January 21, 2011 xmax and power dictate alot even if u had the perfect port area and box that doesnt mean it will be perfect in every car, so a general "rule of thumb" is used alot moreso because there are many configurations one sub can sound good in Quote Link to comment Share on other sites More sharing options...
Berto Posted January 21, 2011 Author Report Share Posted January 21, 2011 (edited) So 12.5sq" of port per cube is a good rule of thumb to go with? And 200sq" is what I was gonna throw out since they said 100sq" for one of them but I wasn't 100% sure it was that easy either. lol EDIT: no T/S parameters are available so I'm not sure of the Xmax and things like that but power for now is going to be around 6500rms total. It might go up to 10k though. Edited January 21, 2011 by Berto Quote TEAM FLEX ISSUES Car: 1985 Oldsmobile Delta 88 Royal 24" Rims HU: 7" Carputer, Planet Audio EQ, iPhone. Coax: T3 Audio 4" speakers Subs: 2x 18" T3 Audio TSNS (walled) Sub Amp: DC 9k SOON TO COME T3 Audio 6x9s MB Quarts 6.5" comp set MAYBE ADDED 2nd DC 9k Link to comment Share on other sites More sharing options...
Torres Posted January 21, 2011 Report Share Posted January 21, 2011 Why do people continue to worry about how much port area there is per cubic foot???? They are NOT related! because not everyone knows what you do not being a smart ass...being serious lol. imo it's a safer to have that than to have people blindy make port area and hope it works. i've seen people ask me about boxes that had 5 sq inches or less for big boxes. and no matter what i think that just won't work Quote Link to comment Share on other sites More sharing options...
bkolfo4 Posted January 21, 2011 Report Share Posted January 21, 2011 xmax and power dictate alot even if u had the perfect port area and box that doesnt mean it will be perfect in every car, so a general "rule of thumb" is used alot moreso because there are many configurations one sub can sound good in Different boxes will sound different in the same car, but port area should be sized based on the port operating without compression and noise which has nothing to do with the size of the box. Sorry. . .just drives me nuts that a couple of manufacturers gave gross estimates on port area based on the drivers they sell so everyone is not calling them asking "how much port area do I need", and somehow it becomes a law that everyone quotes. And I bet over half the people quoting it have no idea how a port should actually be sized. . . Quote Current system: 1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s Previous systems: 2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz. 1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz. Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.