What are the dimensions of the woofer enclosures? If you can get me the dimensions, I'll do some calculations to let you know what would be ideal for porting. What are you going to use to power the speakers?
Thanks for the offer. The inside cavities are prism shaped. They are 45-45-90 degree triangles. The hypotenuse is 15.25 inches. The width of each prism is 15.5 inches. If you could post the equation I (and the community) would greatly appreciate it.
Coder - apologies for the late reply as I've been away from the forums for about a week. I've run some quick numbers and if the dimensions you are giving me are the external dimensions of your enclosure, you don't have a whole lot of internal box volume for these 12" woofers (please see image below). With a 15.25 inch external hypotenuse, you have about an 8.25"x8.25"x15.125" internal box volume for both speakers, or cut that number in half for your volume per speaker - in this particular case about .3 cu. ft. per woofer. Typically 12" speakers should be placed in an enclosure roughly 1.0-1.5 cu. ft. depending on the Thiele-Small parameters of the woofer and a general rule of thumb is the more volume, the deeper the bass.
If you have some extra wood, I would see what you could do to increase the volume of the box a little bit by redoing the woofer board. If you can increase the hypotenuse dimension from 15.25" to 23.25", you'll be able to increase the internal volume for your woofers by a factor of 3, or roughly increase each chamber to 1.0 cu. ft. This increase in hypotenuse length will only add 5.5" to the distance from the back of the cabinet to the back edge of your seat. I don't know if you've mounted the seat or if it has the ability to slide back further from your images, but it does appear as though you have enough space to do this.
If this isn't an option or you don't wish to go down the path of redoing the enclosure, one thing you can do to 'virtually' create additional volume is to place damping material in the enclosures. Typically this is done with acoustic fiberglass, but typical home-grade fiberglass (without the paper) or polyester batting from a fabric store will suffice. You may even have some from the original enclosures. You want to put as much damping material in the enclosure as possible without packing it in too tight – it’s ok to have the speaker rest in the stuff, but you don’t want to compress it too much. Even if you do go down the path of redoing the enclosure, I suggest using the damping material in addition.
As far as porting goes, if you don’t do anything and leave the enclosure as it is, I recommend picking up a couple of these ports from
David Levy Corp. These particular ports will effectively tune your existing enclosures to somewhere around 70-80 Hz. I’d recommend tuning the box lower, but with the current volume and lack of depth available for longer ports, I don’t think it’s feasible.
You can use the following site as an easy reference for tuning any size box –
http://home.new.rr.com/trumpetb/audio/fboxjs.htmlOne other thing I’ve noticed from the images is that the only place where I can tell the woofer board is secured is along the enclosure dividing wall. I’m not sure if this is the case, but these woofers are going to be moving quite a bit with 230 watts driving them – you’re going to want to have that enclosure as secure as possible or there will be an awful lot of unwanted buzzing going on.
Keep up the good work - it's looking great!