tdisport

I've never built a sub box before, so im hoping some of you guys can give a hand with the dimensions of the box. Is there a formula that you have to use to get the right size? Im probly putting in 2 pioneer premier 12" subs. What would be the best size. I also read about sealed and ported boxes. What would be the best for this setup?

Thanks,
Jer

TragicMagic

Use these sites to get started.

http://www.rockfordfosgate.com/rftech/box_wizard.asp <<< Rockford Fosgate Box Wizard

http://www.carstereo.com/help/Articles.cfm?id=31 <<< Port Tuning Calculator

http://www.pioneerelectronics.ca/POCEN/Products/Car+Audio+Video/Subwoofers/Champion+Series+Pro <<< Pioneer.

Depending on the specific woofer you get, it'll likely change, albeit only slightly, the optimum box dimensions. The amount of power you make available for your woofers also affects the design of the enclosure.

There are a few ducks you have to get in a row before you start thinking about the box. However, if space becomes a constraint, you might have to work backwards from there. What I mean is, if space is critical, you can determine the most space you're willing to sacrifice, determine the volume that space allows for subs, then find subs that work in that space. A ported box for two 12" subs is going to be pretty damn big.

You might find it easier to determine what amp, and sub combo you're using, then determine if the box dimensions to optimize their output will fit. If it won't, then you might have to do it over again with a different sub.

Is there a reason why you want two 12's?

tdisport

Someone recommended 12's over 10's because they are basically the same price. So bigger is better i guess....but i never did think about how big the box would be. So im pretty sure that im going to go with 10's then since the limited space i have. And the amp will be the exile shift e500.1.
Would you recomend a vented box or a sealed box....which will be more compact?

jalat

iTrader: (6)

i'd go with two 10"s in roughly a 3 cubic foot shared chamber enclosure @ 35-38hz

TragicMagic

Sealed would generally be more compact. Ported allow for great output.
I, personally, like the sound of both. Though, ported are generally more "bassy". If you heard my sub setup, I'd bet you'd think one 12" sub would be sufficient - maybe not.
Its in a 2cu.ft box, ported, tuned to about 35Hz.

tdisport

Jalat I agree with the 2 10 inch subs...but i do not want them in the same chamber. I wanna put one sub on one side of the trunk and the other sub on the other side of the trunk...and the amp in the middle towards the back. This will allow me to open the floor to get at the spare tire. Will subs in separate chambers opposite each other be a good idea? I want them more 'bassy' so im gonna go with the ported boxes...probly a slot port.

TragicMagic How do I tune to a specific hz? What does that mean? I'm not familiar with this stuff. And in the link you posted about calculating minimum vent size, what does 'Xmax' mean?

Thanks,
Jer

TragicMagic

When you're looking at subwoofers in stores, or online, you should be able to find the XMax on the spec sheet.

http://www.subwoofer-builder.com/xmax.htm <<< Link to XMAX.

Tuning a ported box to a particular frequency (Hertz) is dependent on the length of the port. You pick the frequency, then implement the design that will yield the output you're after. From what I understand, if you're trying to achieve SQ (sound quality) then you alter the port dimensions for a lower Hz like in the low 30's range. If you're after SPL (sound pressure level) tune to the high 40's. If you're looking for something that is SQL, then pick a number in between.

Let's say you had one 10" sub, with a 10mm Xmax, and you want to tune your box to 38Hz, just for the sake of this experiment... Punch those values into the top portion on that port calculator page - I suggest you bookmark it, by the way. The calculator takes that information to tell you what the minimum port area should be to reduce or eliminate port noise, which is a bad thing.
So for those values, it tells us that your port area should be no smaller than 10.04 square inches.

Now that you know what the minimum vent area should be, you go on to the bottom section on that page. We're also going to have to assume the volume of your enclosure. I'm going to go with 1.75cu.ft, only because it is probably close to what you'll end up having. Again, this is something that will be determined once you've picked out your sub(s). Where it says, Is this a Slot Port, select yes. Put in measurements that equal an area no less than 10.04sq.in. I put it 10.5 x 2. Hit calculate length, and it says that it has to be 17.61" long.

Now, if you change the frequency you want to tune to, watch how the length changes. Or if you decided to make it a 10.5" x 1" opening... Play around with it. Keep in mind that 98% of all ports are designed to be inside the enclosure....
Mine falls into the 2%, as my vent is 50% outside the box. See...


It going to come down to what woofer you decide to get.

tdisport

Ok thanks a lot for the info. I think I know enough now to build a proper box. The only thing holding me back is that i cant find the xmax for the PIONEER TSW1007D2 10" sub. Anyone know where i could find this measurement?

Thanks,
Jer

TragicMagic

http://www.pioneerelectronics.com/pio/pe/images/portal/cit_3442/408175373TRD1296Asingle.pdf

At the very bottom of that page, it says that the XMAX is 11.5mm for the 1007.

tdisport

Was talking to a site vendor earlier. He was saying that a shallow mount speaker would require is significantly smaller box than a regular sub. Would that be the way to go if one were tight on space? What are the pros and cons of having a shallow mount speaker? Sound quality any different?