Sweety Posted December 26, 2018 Report Share Posted December 26, 2018 After 16 years of use my old JBL GT3 sub has has gone into retirement & has been replaced with a brand new JBL GT5 12". I know JBL recommend a 1.75ft^3 ported enclosure with a 4" tube port 10" long but here in the UK i'm finding it very hard to get 4" pvc pipe unless it's thick walled drainage pipe which you can only get in a 10ft length & it's not cheap? so am thinking of maybe a slot port or using 2x 2.5" round ports which I have, the sub is being powered by a JBL amp pushing 220WRMS bridged at 4 ohm. I was wondering if someone could possibly give me a plan for an enclosure of something like 1.8-1.9ft^3 my max width is 35.5", hight of around 15" & with as least depth possible so I keep as much room in the trunk as I can Thiele-Small parameters FS(Hz) 29 VAS(l.) 54 QTS 0.58 QMS 6.39 QES 0.61 BL(Tm) 15.2 CMS(mm/N) 135 RMS(kg/s) 6.359 LE(mH) 0 MMS(gr) 223 VD(l.) 0.753 SD(mm.2) 53000 X-Max(mm.) 14.2 X-Mech(mm.) 0 RE(Ohm) 4 General specifications Max power(W.) 1100 RMS power(W.) 275 Number of coils 1 Impedance Z-Nom(Ohm) 4 Reference efficiency η0(%) 0 Sensitivity(dB) 1-W 85.2 Sensitivity(dB) 2.8-V 0 Link to comment Share on other sites More sharing options...
Sweety Posted January 2, 2019 Author Report Share Posted January 2, 2019 Would be grateful for any help & Happy New Year guy's Link to comment Share on other sites More sharing options...
Bret Posted January 2, 2019 Report Share Posted January 2, 2019 To give you a port area to shoot for I think you need to provide a desired tuning frequency. At 35Hz you would need about a 17 square inch port, which is much larger than 2.5" tube. I used Triticums Port area calculator, which I recommend you get acquainted with. I just went with a slot port because I got tired of looking for tubing and didn't want 6' of it in my apartment. I pulled 35hz out of my ass, not recommending that tuning. Link to comment Share on other sites More sharing options...
Sweety Posted January 2, 2019 Author Report Share Posted January 2, 2019 25 minutes ago, Bret said: To give you a port area to shoot for I think you need to provide a desired tuning frequency. At 35Hz you would need about a 17 square inch port, which is much larger than 2.5" tube. I used Triticums Port area calculator, which I recommend you get acquainted with. I just went with a slot port because I got tired of looking for tubing and didn't want 6' of it in my apartment. I pulled 35hz out of my ass, not recommending that tuning. Thanks for your input Bret, I was looking at setting the tuning to 33-34hz, I may have tracked down some 4" pipe but at the moment can't find a 90' bend to fit it as I really need to keep the enclosure as shallow as I can for room in the truck. The car is a Ford Mondeo which is like the Ford Fusion sold in the US I was planing on having the sub rear firing along with the port but am now wondering if I had the port firing to the side if it would sound ok Link to comment Share on other sites More sharing options...
Bret Posted January 2, 2019 Report Share Posted January 2, 2019 As long as you don't have anything obstructing the port , out the side is fine. And the area of a 4" circle is 12.57. Someone else will have to chime in here, I don't know if that would give you port noise or not. Link to comment Share on other sites More sharing options...
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