IA 12" 187 box help

[SCcobra4me 10+ year member]

I'm running two IA 12" 187's off an old school Punch 200, I built the box (inside dimensions) 36" x 14 1/2" high x 17" deep with a 4"x15" slotted port 12" deep as recommended by the site specs, giving me roughly 4.5 cf^3.

I wasn't too impressed (these subs seem like they had more in them) as it didn't hit that hard and the low's seemed to be bottoming out so I took out the slotted port and added two 4" pvc ports 12" deep. Well the low's are lower, louder, cleaner now and the mid-bass seems to hit harder but I lost my highs. What can I do to balance out the highs and get the mid-bass to hit a little harder?? Longer port, shrink the box, etc?? I'm willing to give up some of the low bass to balance out the others.

Thanks.

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[4OZGLOVES 10+ year member]

Tuning around 36 should get you nicely into the 60-80hz range and still catch the lows alright, at least it seemed like the sweet spot for tuning my L7 8's

 

[SCcobra4me 10+ year member]

I tried playing around with the tuning calculator and it wasn't much help. Does making the port shorter or longer increase the hz range?

 

[4OZGLOVES 10+ year member]

I tried playing around with the tuning calculator and it wasn't much help. Does making the port shorter or longer increase the hz range?

PORT Size Calculations and Formulas for WOOFER and Subwoofer BOXES

If you box is 4.5 cubes and each port is 12" long your port would be tuned around 32, If you take it down to around 8" per port it will effectively raise the tuning to 37-38 which would get you into the 60-80hz range with more authority

 

[SCcobra4me 10+ year member]

Thank you sir, looks like I'll be shaving off a couple inches tomorrow.

FWIW, my box is more around 4.75 cf^3 now without the slotted port, if that matters.

 

[iamamp3pimp 5,000+ posts]

that box is really big for those subs imo.

shrinking the box should increase the output in general, as well as raise the tuning some.

 

[SCcobra4me 10+ year member]

that box is really big for those subs imo.
shrinking the box should increase the output in general, as well as raise the tuning some.

So what are you suggesting because that's my second option I was going to do, I was going to shave 2" off it which will take it down about .6 cf^3. Bringing total volume down to 4.15cf^3. I might go 1.5" though and try and keep it around 4.25.

Right now I'm kind of playing with the box, it's a cobbled up POS right now but once I find the sweet spot, I'll redo the entire thing again. I plugged one of the ports up today just to see how it'd sound and the box didn't like that, the two 4" ports 12" deep seem to do very well. Hopefully like you said, bringing down the volume with up the output.

I know what I'm doing tomorrow, thanks for the help.

Also, what's recommended for a trunk car with the back seats that fold down cuz right now I have the subs facing the rear seats. I know in a hatch they recommend facing the trunk but I was thinking about firing them up but didn't know if that would cause too many unwanted rattles.

 

[RAM_Designs 5,000+ posts]

You were tuned to 42hz with the slot port and 31hz now with the 12" long PVC ports...shoot for something in the middle, like 35hz, and you'll probably be happy.

 

[iamamp3pimp 5,000+ posts]

fire toward the rear of the car imo.

 

[SCcobra4me 10+ year member]

that box is really big for those subs imo.
shrinking the box should increase the output in general, as well as raise the tuning some.

Well I got ambitious today and redid the box, brought it down to 4.15 cf^3 roughly with two 4" ports 10" long and didn't gain anything. It sounds worse on almost all levels, what the heck am I doing wrong?

I shoved two towels in the ports but have yet to test out what it sounds like but a low volume it doesn't sound too bad, I may just go sealed!!

 

[SCcobra4me 10+ year member]

I redid the box once again today, made it as close to 5 cf^3 as possible with two 4" ports 13" deep. Minus the highs being a tad weak which I could care less about, the mids and lows sound phenominal, way cleaner and louder than with smaller ports or less cf^3.

I also rewired my punch 200 to 1 ohms which helped push the subs a bit better also, but now my **** PVC port fell out (never had that happen). Looks like I'll be getting the Gorilla glue out.

 

[rosshimself13 10+ year member]

thread full of fail

 

[chillin 10+ year member]

the big box probably sounds better because you were sending 200 watts to subs that want 600+

 

[DBBOOM 10+ year member]

4cuft, (2) 4" ports 12" long and 500RMS each.....................done and done.