posted
I am using a DD 9512d and DD recommends (for daily driving) a 2.5 cu.ft. box, tuned to 35Hz, with a 13 in. port and 20 sq.in. of port area.
1) Would it be better to make (1) 13 in. long port tube or (2) 6.5" tubes, or (3) 4 1/3" tubes, etc.??
2) Where should I place my port tube--next to the sub (left/right of sub's surround), on top of the box, or somewhere else??
3) What are the pros and cons of using more port area--more SPL, worse SQ, effects on tuning frequency, etc.??
Please tell me what factors I need to consider with this. The DD 9512d is going in my 92 Lumina sedan for daily driving only--no comps. Sorry to make it so complicated but this is my final sub and I want to do it right. I really appreciate your help!
Posts: 400 | From: Belmont, MI/Valparaiso, IN | Registered: May 2001
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It's best to use a single large port over several small ones. Using many small ports results in the same port area, but more surface area inside the tube, which means more port noise...
Having more port area will increase your max spl output by keeping port velocity down. This will also improve SQ. If you play only low levels, you won't need a lot of port area. However if you're getting a 9512, I suspect you really want to slam, so i would use more port. Unfortunatly, the more port area, the longer the port must be to maintain your desired tuning frequency.
Generally you should place your port on the same plane as the woofer (any orentation to the woofer, doesn't matter much), however you might get better results by putting the ports on the top woofer on the side, or visa versa. Depends.
Keep in mind how hard you want to run your system. If you like tons of output, I would opt for more port area.
Adam
------------------ Demo Car - twin RF HX2 15's JBL 600.1 on each 9 cuft ported box, 75 sq inches of port tuned to 35 Hz JBL 180.2 on as yet undecided components, Infinity Kappa 6.5's for now... Db's:???? soon to come
quote:Originally posted by Atomic Fusion: However if you're getting a 9512, I suspect you really want to slam, so i would use more port. Unfortunatly, the more port area, the longer the port must be to maintain your desired tuning frequency.
DD recommends 20 sq.in. of port tuned at 35Hz, with 13 in. of port length (2.5 cu.ft. box). I don't have enough room in my trunk to have one long port--I think I need two port tubes (I don't want a large diameter tube). So I guess my question is what length must each of the 2 ports be (and 3" diameter-small as you recommended) while keeping it tuned at 35Hz? Sorry for the long question but if I get this part down I'll be good to go. Thanks for all your help.
Posts: 400 | From: Belmont, MI/Valparaiso, IN | Registered: May 2001
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posted
Oh, and I would like 30 sq.in. of port unless the SQ would be reduced.
Posts: 400 | From: Belmont, MI/Valparaiso, IN | Registered: May 2001
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If you use two 4" ports (which is what I recommend if you need to keep port length down as much as possible). Make each port 18.6" long and this should tune your box to 35 Hz and give you about 25 sq inches of port. Make sure when you construct your box you take into account woofer and port displacement!
The displacement of the two ports will be 0.27 cuft. Make sure to add that volume to ur box when you build it (and add volume to compensate for woofer displacement as well!)
Adam
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Current Demo Car - twin RF HX2 15's JBL 600.1 on each 9 cuft ported box, 75 sq inches of port tuned to 35 Hz JBL 180.2 on as yet undecided components, Infinity Kappa 6.5's for now... Db's:???? soon to come
And no I'm not trying to show off my artwork skills, cuz I don't have any!
Anyway, with the port length, it MUST be no more than 10" cuz I have to make the depth of my box 12" and I was told to leave 2" between the end of the port and the back of the box. I'd prefer a 10" long port if possible.
How would a 4"x6" port do if it was 10" long? That would give me 24 sq.in. of port area, in a 4"x6" rectangular port, right? I know it's 24 sq.in. of port area, but DD recommends 13" long ports and mine would be 10"--is this still okay? Thanks for all your help--I really appreciate it as this is my first ported box.
Posts: 400 | From: Belmont, MI/Valparaiso, IN | Registered: May 2001
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posted
Your box would be tuned in the neihbourhood of 45-50 Hz. Rather high for music.
Adam
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Current Demo Car - twin RF HX2 15's JBL 600.1 on each 9 cuft ported box, 75 sq inches of port tuned to 35 Hz JBL 180.2 on as yet undecided components, Infinity Kappa 6.5's for now... Db's:???? soon to come
posted
How much longer do I need to make the port if I want 24 sq.in. of port? Or should I just stick with 20 cuz there won't be a big difference in output?
Posts: 400 | From: Belmont, MI/Valparaiso, IN | Registered: May 2001
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posted
Just go with the 20 sq inches. You'll still be tuned high if your port is only 10" long, though. Maybe put an elbow in it.
Adam
------------------
Current Demo Car - twin RF HX2 15's JBL 600.1 on each 9 cuft ported box, 75 sq inches of port tuned to 35 Hz JBL 180.2 on as yet undecided components, Infinity Kappa 6.5's for now... Db's:???? soon to come
posted
Yeah--finally know what I need now. DD recommends 13" long tube for 20 sq.in. and since my box is 12" deep (2" between end of tube and back wall of box), looks like I need a 3" long elbow. Where can I buy these elbows?
Posts: 400 | From: Belmont, MI/Valparaiso, IN | Registered: May 2001
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