I have two kicker l7 12s and i wanna put them in a ported box. I have enough room in my trunk to build a 7.5^3 ft box (minus the port). However kicker recommended 6.5^3 ft MAX airspace for for them. I was wondering if the extra 1 cubic foot of airspace would be dangerous for the subs or if itd make them more efficient? I want LOW lows.


Also if it does work do you think a 4" port for each sub would make the lows lower or should i keep the port at 3" max?

Thanks, Blue.

 

this might help you out Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators its what i used in the past for my box

 

Just to answer your questions. Yes that big of a box will hurt your subs if putting rated power or more than rated. If your using a crappy amp then a big box will help the output. 3" or 4" port doesn't mean anything without knowing the hight of the port and knowing your airspace. Also 1 common shared port for both subs will be better than a port for each. You need to read up on alot before I suggest you building your own box.

 

Ive built 4 of my own boxes before and they all sounded nice and made good clean bass. Im was just wondering if too much air space is bad. Ive decided on a 6.8^3ft box including the port. Itll be 4" wide for each sub.

Thanks for the posts everyone!

 

too much airspace can be bad... however the worst thing you could do is build the box too big so the air cant travel back to the cabin from the trunk (if its firing backwards)

 

No problem, Do you know how many square inches of port 4" x X is? Or what the airspace is after port and sub displacement? Or length of port for tuning? Or just gonna wing it?

 

Is it going to be a circular port or square? If circular you need more port area(I didn't do the math but rule of thumb is around 19 sq in per cf).

 

Actually rule of thumb is 12-16sq in per cube for the best performance and flattest response. Seems to me that about 15sq in port per cube is what works best from my experience with DC audio, FI, Sundown Audio, Skar Audio, and I've done alot of Kicker CVR's and a few SoloBarics(Usually singles tho).

 

a single 4" will have port noise. maybe just maybe a single aeroport may not but u would have to be damn lucky or not listen to it loud

 

I hate port noise

 

me too... i opted to leave the port out for that reason

 

Thats interesting, I've done a few single 4" ports with 2 12"s about 14.5-15 sq in port per cube. Zero port noise. I do however always 45 the port corner then some boxs I 45 all the other corners too but not always..

 

what subs were u using? 45s might be the trick then again port placement and box dimensions really play a huge role as well.

mind you im talking about circular ports not square ports

 

I've done 2 boxs with DC audio Level 3's both ended up being 4" ports. Just a regular L port on the driver side. 1 was a cut-through in a single cab ford ranger and 1 was in a scion tc coupe. I also did a box for some alpine type R's that had a 4" port and didn't have any issues with port noise. My 2x 10" box I just did for my cobalt ended up being 3.25" x 12.5" port.
Ya, i'm not sure I do 45's on the port corner and 3/8" round over at the corner of the port wall and the begining of the L port. Also roundover the port edges exiting the box. How I do all my boxes, then my personal boxs and close friends I'll 45 all the corners but usually not for other people too lol

 

oh ya a 4in L port is enough i was talking about a round port

 

Oh my bad thought we were talking about slot ports. Then ya 4" round port or areo port definitely not enough.

 

I am referring towards SPL setups, for SQ or SQL I honestly have little idea. lol. It also depends on the excursion of the woofer and of course rear cone area(unless running inverted, then just plain ol' cone area).

 

I am also referring to SPL. You'd want to stay on the big end 15-16 sq in port per cube. When really getting into numbers I always suggest giving the manufactur a call or email.

 

Yeah but unless it is a botique brand the manufacturer is just gonna rattle off some random number which could be rubbish. I run all my boxes through winisd and it measures port area based on driver requirements in the given airspace.