Box help! Box/Port Volume and etc. Please help! (Advice)

[FeelDaBass]

Hi, so here's the deal. I'm on my break in between semesters at college. I, today, just got my second Rockford Fosgate 15" sub. One T0d415 & one T1d215. Wiring to 3 ohms on my Rockford T1500-1bdCP for over 1200 watts (in the future wire it to 1.33 ohms). I am going to make a box for both of them sealed off facing in the cabin. I'm having a problem, which is deciding how big I should make the box and port & also what frequency to tune it to. Rockford's recommended "high output" box is 3.25 ft³ net tuned to 38 htz (I am currently running this with one 15" facing rear). It hits pretty well for what I like, and I listen to mainly dubstep and rap with some old rock and hard rock.

My car is a '98 Chrysler Concorde with over a gross volume of 13 ft³ to play with without going around much inside the trunk. I would like to keep some room in there, however, and would LOVE to be able to get my spare tire out if needed.. My dimensions for my box I am thinking of making is 36x18x24 with a gross volume of 7.41 ft³. Tuning to somewhere between 32 and 38 htz, not sure yet, any advice is great. I think I'm going to maximize my port area and make a middle slot port with the dimensions of 3.5x16.5x...? (I have to cut some medal in my car to see if I can widen my box some more for more port area).

If you have any input/advice or anything, I'd love to hear about it. I'm going to aim to make my box 38 inches wide but I'll have to see how much I can cut away (soon!). Mainly need advice on the net volume of the box and the port area and tuning.

[Smoove]

Before you get to box specs. It is not recommended to run 2 subs at different ohm loads.

[FeelDaBass]

Does it matter? Isn't it just the final ohm load that counts? And all voice coils receive equivalent wattage..?

[FeelDaBass]

Well, I only see one thing from yahoo about that difference in ohms thing. Will it really affect it that much? Can anyone explain what happens when doing that?

[will77530]

its not the reccomended practice but in theory shouldnt effect anything

[FeelDaBass]

I wouldn't think it would, especially in series.. It's not too easy to test, that's the tricky part here.

[Joe X]

Does it matter? Isn't it just the final ohm load that counts? And all voice coils receive equivalent wattage..?

Connected together one sub will be receiving more power than the other unless you leave one of the subs with one coil disconnected (bad idea), that will half the power handling of that sub. Still acoustically are different as are not same series so in a common chamber box cancellation may occur.

Is not like it can't be made to work, just will not get best possible results, probably bad results, much easier switch one of the subs to get a matching pair.

[Truconcept]

i spy with my little eye the forming of a double post lol

http://www.stevemead...erent-ohm-subs/

so not only ru gonna do what pretty much everyone says not 2 do

but your going 2 build a box for them?

rofl why dont u take that box building money and get your expensive rockfords correct?

u keep asking what could happen...... FIRE (thats a good enough reason imo)

goodluck either way!

[bkolfo4]

The subs will not receive the same amount of power.

If you series the coils on each sub, and then parallel the two subs (I assume that is the plan for a 2.7 ohm load), and the amp makes 1200 watts, the d4 sub will get 400 watts, while the d2 sub gets 800.

Does not mater how you wire them unless you only run one coil on the d4, but that cuts the power handling in half.

[FeelDaBass]

I'll most likely be selling one of them, not sure which one though, as just the T1d215 sounds nice and loud! But I like wiring options with 2 d4s. May build a box where my back seat is but probably would't wall that one, since it's just the two 15s (future tense). Maybe with 18s down the road though...

Thanks for all the input though.