One SA-12 box build help

[stiffler style 9]

Hi,

I'm new but a long time lurker of this board.

I've finally decided to purchase a sa-12 and add a subwoofer to my car. (Bmw E46 Sedan)

Before I purchase, I would like to get the box sorted out. I've been using some different calculators and various threads from this board to figure out how I should build the box. I have the whole trunk to use so no space constraints. The sa-12 says 1.75-2 cubic feet which leaves very little to no room for a port. I want to tune to 35 hz. I looked into maybe one 6" aero port, but it would be a stretch to get a 2 cubic foot box to fit the sub and the port which would be 14-16" long.

Any help or suggestions? Would a passive radiator be more doable?

thanks in advance

[40oz 1]

If you have the room, a slot port would probably be the better option. Its easy to build, cheaper and also provides bracing for the enclosure.

I do have a single SA12 in an aero ported box though. Its 1.9 cubic feet after all displacements with (2) 3" aeros, 18.5" long. It is tuned to ~32 Hz. It sounds great, no port noise and the box is directly behind my driver seat so it would be easily audible if there was any.

[StreetLegal 119]

Here is a design I did for an sa-12, it was designed to use more power to sub than it's actual rms rating.

http://www.soundsolutionsaudio.com/forum/topic/56355-new-box-for-a-new-sub-1x12-advice-needed/

[dbsupra 69]

I've built 3 different boxes and by far my favorite was 2 cubes tuned at 35hz.

I vote for a slot port. Much easier to get the tuning and port area you need.

Not familiar with your car but sealed off from the trunk would be another option.

[stiffler style 9]

40oz,

Would you mind telling me the dimensions of your box? I like the idea of aero ports as I had a lot of port noise with the last sub box I built, however, I'm sure I built a subpar box at that time.

Where were the ports placed in comparison to the subwoofer?

I would be placing the box in my trunk, however I am removing the rear deck speakers which would open up the holes to the trunk.

Thanks!

[40oz 1]

Yeah the dimensions are 13.75" x 13.75" x 29". The sub and ports are on the same baffle, on opposite ends. The ports have a 90 degree PVC elbows and bend toward the sub inside the box. There is a double baffle for the sub/ports. The ports are 18.5" end to end, including the flares. I have the sub and ports firing up into the rear window of a hatchback.

It would probably be wise to do a little research to see which way other people have aimed their sub/ports in your specific car and have had success. Sub up port back, sub up port to the side and sub back port back seem like good option to explore. As was already mentioned, sealing off from the trunk would probably have good results as well, if you are willing to go that route.

[stiffler style 9]

Thanks for the help guys.

I'm going to design the box StreetLegal posted and see how it goes.

Would one SAX-1200D be overkill for powering one SA-12?

Also, from what I read on bmw forums, the bass is much more prevalent when the rear deck speakers are removed.

Edited August 13, 2012 by stiffler style

[StreetLegal 119]

Set the amp gain appropriately and the sax 1200 D would be fine, exellent choice on the amp.

Edited August 13, 2012 by StreetLegal

[stiffler style 9]

When I looked, the sax-1200d was out of stock for whatever reason on this website. While I look for one in stock somewhere else, what other amps would you recommend to be comparable and useful for my situation; possibly less costly?

Also, after doing some sketches and what not for the box build, I think I should kerf the back two corners along with the inside wall of the vent. Is that going to be unnecessary and more time consuming than useful?

Thanks for all the help

[wannabang 13]

I loved the idea of kerfing, but since I was tight on time, I skipped it. I just use 45s inside the box. Not as efficient, but they work.

Check out the AQ750 ($199), it's 750 at 1 ohm @ 14.4 volts, and if you're not running 14.4 volts, no worries, it'll be fine, Still, you should be modest with the gain, always. Woofersetc.com has a SAZ-1000 ($299) which would be a perfect match for the one SA-12 @ 2 ohms.

I'm in favor of the slot port, as well, don't be afraid to do some math and make sure that port is perfect to eliminate as much noise as possible.

Good luck with the build, my man!

[stiffler style 9]

I have plenty of time as I'm a college student so I don't mind doing the kerfing if there is going to be a more than negligible benefit from it. I was planning on using 45's in the corners I'm not kerfing as well.

Thank you for the amp suggestions. Greatly appreciated.

Where would you suggest I check my math? Such as an online calculator of some sort for this application. I'd love to build one great box rather than two crappy ones.

Edit* I found a calc on carstereo.com however I have some questions. Which measurements do I use to find the internal volume? I'm using the design StreetLegal posted in the thread he linked. Do I use the 22 1/8 x 11 5/8 x 13 1/2 and the rest is considered port area? If that is correct than the 33.96" port length I'm getting is about perfect with what is already laid out. What happens if the port length is too long or too short?

Edited August 14, 2012 by stiffler style

[wannabang 13]

Use the Torres Box Calculator. It is my favorite, hands down, and super easy to understand and use. The port length will be what determines your tuning frequency, and the height and width will determine you port area, generally speaking.

http://www.mediafire.com/?w40an4l5ygh56g8

Lemme know if that link works. I got it off SMD's forum. Or you can google it.

Edited August 15, 2012 by wannabang

[stiffler style 9]

The link works. I'm on a mac so I'll have to download it on my windows desktop for it to work. Thanks for the help!