Sweety Posted April 28, 2018 Report Share Posted April 28, 2018 I'm planing on building a new box & was hoping someone could check over my plans to see if I have calculated it correctly. It's going to be a wedge shape so it fits up against the back seat so I get as much room in the trunk as possible the aim is for 1.9ft^3 & tuned to 35Hz Width 35" Height 15" Top panel 8" depth Base Panel 11.5" depth Port internal size (made from 3/4" MDF) 4" x 4" & 15" long Sub being used is an old JBL GT3 12" getting powered from a 220wRMS JBL amp I know this is probably simple maths to most of you but I suffered from meningitis 22 years ago & it wiped out some of my memory & am still relearning things Link to comment Share on other sites More sharing options...
Joe X Posted April 28, 2018 Report Share Posted April 28, 2018 Your calculations check out (almost) assuming your square port has no common walls with the box, also I assume your port is firing sideways, if your port has common walls with the box then your tuning would be down to about 33Hz. Link to comment Share on other sites More sharing options...
Sweety Posted April 29, 2018 Author Report Share Posted April 29, 2018 Thanks Joe X, yes the port wouldn't be part of any of the walls but would need a 90' bend in it as it would have to be rear facing with the sub due to truck space, my other option which will be a more costly one as pvc pipe isn't cheap here in the UK would be to use a 4" pipe which I think for a 35Hz tuning point would need to be 12.5-13" long with a 90' bend in it but if I got this way i'm not sure what the volume of the enclosure would be but guessing it would be close to 2ft^3 Link to comment Share on other sites More sharing options...
Joe X Posted April 30, 2018 Report Share Posted April 30, 2018 In the case of a 4" round port it would be close to 11" and yes net volume would be 2 cubic feet net, anyways here's a simple way to do a slot port firing back with only two pieces of wood, this would be 1.94 net @ 35 Hz with a 4x4 port: Link to comment Share on other sites More sharing options...
Sweety Posted April 30, 2018 Author Report Share Posted April 30, 2018 Many thanks Joe X for your help as it has helped me a great deal & gives me 2 different options. Now I have to find somewhere to mount my as it's just been screwed to the back of my temporary box Link to comment Share on other sites More sharing options...
Sweety Posted May 2, 2018 Author Report Share Posted May 2, 2018 Think i'm going to have to change my plans as a square port isn't going to do it for me when it comes to looks & 4" pvc pipe here in the UK isn't that cheap & all I can find is thick wall pipe? ideally I would like a wedge shaped enclosure 14" high, around 35" wide (can't go wider) & with a difference of 3" between the top panel & base so it would fit nicely against the back seat with a 2" wide port but i'm struggling badly to work it out. I have tried to work out a rectangular enclosure but think i've got the maths wrong 34" wide, 14" high, 11.25" with a 2" port 24.8" long would give a 35Hz tuning & a net volume of 1.9ft^3 ? net volume can be dropped to 1.8ft^3 if needed Sorry for being such a pain with all of the questions & asking for so much help Link to comment Share on other sites More sharing options...
Sweety Posted May 3, 2018 Author Report Share Posted May 3, 2018 I've just downloaded the torres calculator & wondered if I put the right info in & also wondered about the wedge shaped enclosure details mainly for the port length as the port would go along one side & along the back of the box & is thereenough port area ? Link to comment Share on other sites More sharing options...
ckeeler11 Posted May 3, 2018 Report Share Posted May 3, 2018 If the port goes top to bottom along 1 side then it should be 3 common walls. Top, Bottom, and Side. Link to comment Share on other sites More sharing options...
Sweety Posted May 4, 2018 Author Report Share Posted May 4, 2018 Thanks for that port will have to be in an L shape to fit in the box so that would make it 4 common walls then ? I better change things then &will put up the changes to see if it works out right Link to comment Share on other sites More sharing options...
ckeeler11 Posted May 4, 2018 Report Share Posted May 4, 2018 No still 3 after it makes the turn it is Top, Bottom, Back. Link to comment Share on other sites More sharing options...
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