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View Full Version : a few questions on SPL enclosure



AScreenName
04-08-2004, 03:38 PM
my friend who owns an RE 15 XXX wants to compete in the local SPL competition that comes around each summer, and possibly in other competitions in northern california if we can find any.
so i was thinking about what kind of box would be good to build for SPL
heres what i came up with:

a 10.13 cu ft enclosure, tuned to 44hz
the dimensions would be 20" high X 25" deep X 35" wide
we would make a slot port, and have the actual effective port area be outside of the box, kind of like a protrusion, so the vent doesn't displace any internal box volume and screw up the tuning frequency in the process.

i figured we would use the bottom of the widest side, and make the port area 33.5" (each .75" of MDF on each side displacing 1.5" from the 35" side) by 5". when i went to a site to calculate what the vent length would need to be, it said it would need to be 10.13" long. i was wondering if somone could check my calculations, approve of this idea, or possibly recommend a diffferent/easier plan?

thanks guys, appreciate it

tommyk90
04-08-2004, 04:02 PM
That is a HUGE box, even for a competition.

I'd say something around 5-6 cubes tuned to 44-45 hz would be a little better suited to 1 15".

InhumanAcura
04-08-2004, 05:47 PM
What kind of vehicle and what is the resonant frequency?

ngsm13
04-08-2004, 09:43 PM
Well, honestly....like tommy sed, doesn't need to be tht big! I mean, keep the port inside the box...make it like 7 cubes net. MORE MORE port area...like 100-150 sq. inches of port. Tune it like 56hz or so...should peak around 58-59. peace

NG

jbl_marshall21
04-08-2004, 10:52 PM
what kind of program r u using? if its the pro then it calculates the port displacement

AScreenName
04-09-2004, 12:56 AM
its going into the back of his jeep wrangler

i think i'll do a 6 or 7 cube box

should we really tune it that high? 55hz or so?

ngsm13
04-09-2004, 01:38 PM
****, is it a hard to wrangler? hopefully so, because if it's a canvas top it's pretty much useless to compete SPL wise...even with hard top...check for leaks and **** around seams. And, yes, i'd tune it 50-53hz or so. peace

NG

LoneRanger
04-09-2004, 07:19 PM
****, is it a hard to wrangler? hopefully so, because if it's a canvas top it's pretty much useless to compete SPL wise

I was thinking the same thing when i read the initial post. For SQ in a wrangler, your best bet is to downfire the box. Assuming its a hard top, your best bet will be upfiring with the sub on the same face as the port. If it's a canvas-top wrangler, your best bet for SPL will be to put your equipment in a different vehicle.

AScreenName
04-10-2004, 12:38 PM
its a hard top
we might be able to borrow a friends like 2000 dollar thicker than hell hardtop for the comp. we were thinking maybe we could get some 2X4's to put from the floor to the top to reduce flex LOL. ghetto as hell.
so we should downfire the box?

LoneRanger
04-10-2004, 01:55 PM
Sorry...i just reread my own post and realized how confusing it sounded.

Downfiring boxes are for SQ purposes, not SPL.

You will probably want to up-fire the box for SPL. This means both port and subwoofer on the same face pointing toward the top of the cabin. You might also try rear-firing (both sub and port facing the back of the cabin). I'm sure they'll have a clinic at any event you go to so you'll have a chance to try both methods and see which works best for your vehicle.

smkmotorsports
03-29-2005, 01:44 PM
i'm building a box for 2 AW1200Q's for competition and i called audiobahn and they told me the box should be 37-d, 41-w and 18-h=13.38 cu.ft. and a port of 100sq.in. and it should be tuned at 30-34 Hz with a spike at 34Hz and 7.4dB the meter is 97" from the box, can you guys tell me if this would be a good box for competition and what should be changed? It's will be in a 2000 Ford Expedition.

Thanks
Rob

ngsm13
03-29-2005, 02:01 PM
i'm building a box for 2 AW1200Q's for competition and i called audiobahn and they told me the box should be 37-d, 41-w and 18-h=13.38 cu.ft. and a port of 100sq.in. and it should be tuned at 30-34 Hz with a spike at 34Hz and 7.4dB the meter is 97" from the box, can you guys tell me if this would be a good box for competition and what should be changed? It's will be in a 2000 Ford Expedition.

Thanks
Rob

Way to bring back up a year old thread ;)

Could have started one yourself...about your personaly question ;)

NG

pacho
03-29-2005, 05:53 PM
Rob, first of all you need to find the resonant frequency of your 2000 Ford expedition and that will be the tuning freq of your port. 13.38 cubic feet sounds a bit big for 2 audiobahns but maybe some other CAF members can voice their opinion on it.