Need A Little Help Building Sub Boxes

[cam_R33]

i have two 12" type r alpine subs that i am putting in the corners of my skyline, just wondering what size the boxes should be and also what thickness mdf i should use? also should the subs be facing each other? if not should i angle them towards the front of the car or the rear?

cheers Cameron

[nissanskyrice]

I know you can buy premoulded boxes for about $350 that fit into the rear passenger side corner of the boot but havent been able to find any for the right corner strangely enough. might be different for the r33 though so could be worth asking car audio places if they can source them. then again if you really want to make them yourself youll save a fair bit of $$$. would want to use atleast 10-12mm thick mdf and then fibreglass it for added strength.

[cam_R33]

yeah i had a look at some premoulded boxes but they are way too expensive, so im definatly going to make my own boxes and i want to have boot space left so i am putting them in the corners and i need to know the smallest box size for the alpine 12" type r subs, (i still want them to sound good).

[nissanskyrice]

Yeah dunno about the sizes. ive seen on some manufacturer websites they actually list it but i couldnt find it on the alpine website. maybe if you find a very similar specced model sub from a different website that lists the min box volume u could just go off that. or look on some car audio forums and people will probably know off the top of their heads. Fhrx on this forum might know. (he has a sticky at the top of the car audio section for installing door speakers) maybe just pm him or something. from the majority of his posts on this forum it looks like he would know or be able to find out easily.

[Fhrx]

The enclosure will need to be constructed from at least 18mm MDF. The volume of the enclosure changes depending on the install but as a general ball park figure I'd aim for around the 0.9cf to 1.1cf sealed region.

[MyStag260]

Hey mate, i have found and its by no means a scientific fact and someone will probably tell me im wrong but... the Alpine type-Rs are suposed to have about 32litres or around 1.15cf or there abouts, regarding the sound though i think that having it this size it booms, really deep bass, but being a trance, electro type person i wanted mine to be as tighter sounding thump as possible so i made mine around 29litres or there abouts. Of course you will need to power your subs effectivly to get the best out of them. But you should choose the kind of sound you want

just my op

[mikel]

old thread, but I was curious to see what the theoretical response calculated to.

I wish Alpine would publish the specs on their drivers, but I found the specs for the 12" SWR 1241D on this website:

http://www.thielesmall.com/database.asp

Vas =58 litres,

Qts= 0.43

Fs = 28Hz

building the box at 32 litres gives a theoretical Qtc of 0.72 and an F3 of 46Hz. If you weren't short on space this provides a very good response shape

if you're prepared to put up with a small amount of peaking at the expense of some transient response (still way better than a ported box) you can drop the box size to as low as 13 litres which gives a Qtc of 1.0 (as high as I would ever go) and an F3 of 51 Hz - so lose 6Hz of response, but a get little boost in bass so that the ear could never tell and have a much smaller box

cheers,