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Discussion Starter #1 (Edited)
ell i'm trying to decide something, whats the power to enclosure size that will work with the tempest?

Right now I have 500rms @ 4ohms on tap. In the progress of building a very strange shaped box (mostly to fit around the contours of my back seat, as well as my spare tire) so i've yet to put any fleece on the front of the box, but as my calculations go i'm right at 2.6cf, granted that is the low end of the volume, as it could be .1 or so cf more here and there (when i did the math i accounted the spare tire as a rectange instead of a circle). Won't completely know till its complete. But with 500rms on tap sealed? what kind of relationship would i have power to enclosure size. As i'm trying to get it up to 3.5cf if at all possible, sealed or possibly ported to mid 20's. Would 2.6 at the low end of the spectrum be a decent box for a SQ install granted the amount of power i have?

But trying to squeeze that extra cf out of it will be hard to get me to 3.5cf so what should i do as far as my final volume, and sealing or porting it low?

I'm just trying to make a good idea of what i'm working with right now, as i'm having to work around a spare tire which is the reason i'm having such a hard time figuring my size, as i'm loosing almost a complete foot with it. Any ideas?

This power to enclosure size relationship is the point of sub effeciency in a large box vs. extra power in a smaller box to get the sub to reach max excursion. But i wonder how much small is small enough to drastically choke the sub, and impact both SPL levels and possibly SQ and detail. I have a HT sub (Tempest as well) in a 7cf box tuned at 21hz, with 200rms on it. It sounds fantastic, but would i get the same sound out of a box at 3cf with 500rms on it (be it sealed or Ported depending on ending volume, but hopefully ported mid 20's).

Sorry for all the gibbergabber.......

BTW F3 for the tempest in 3cf sealed is 36hz Qts is .83, 3cf ported 23hz is 32hz but the ports are each 38" long and i dunno but i think i can fit them in there, they will need to be facing each other basically overlapping to get the length. I sure wish i could get a few more in outta this box :(, but will i still be ok either sealed or ported with the size i'm working with? Or is this room for an Atlas 15" to try?
 

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2.6cft sealed is fine, especially with the power you have. Higher qts alignments generally lend themselves to flatter, tighter sounding bass in car.

If you want to experiment, you can stuff with 1lb of polyfill per cft. to increase the volume by 50%.
 

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Discussion Starter #3
What is the gereral consensus for the type of sound for a sub, I want it only so tight...

But i would like accurate and deep bass, as it looks 2.6cf is .88qts i'm gonna try for 3cf and thats .83 so that should loosen the tightness up a tad as well. I'm not exactly sure how tight any of those alighnemnts are as i havn't messed around much with sealed boxes.
 

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I like the tempest in a larger box, as your HT setup is.
I find if the Qtc isn't low enough, the bass is too pronounced, (less tight sound, but greater amplitude) probably due to a lack of dampening around resonance causing a very noticeable peak. So for the temnpest I would prefer a slightly over damped design.
As you go lower with your Qtc goal, I would say tightness would increase, and amplitude would decrease, but that's probably what you mean and we are saying it differently. :)
 

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Discussion Starter #5
Well i crunched some new numbers tonight, and such and took my box from 2.6 up to 4.75cf, 4.58 counting sub displacement. Will that do nicely for the sub now? Also not exactly sure on keeping it sealed or if i should port it for low end extension.

Opinions?
 

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It's hard to recommend a box size without knowing the acoustic response of your vehicle, not to mention the target frequency response that is personal preference. In all reality then, it doesn't really matter. Take a guess, and if it doesn't pan out then use the equalizer to shape the response to how you would like it to sound. At least that's how I usually do it, since the in car response is just so way off from anything I'd ever guess that the box really doesn't matter all that much.
 

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Discussion Starter #7
Wow seems strange to me that you would suggest just to EQ it out, Which isint really a problem, but i do like a flat response with a little more low end. I'll try something like 4.6 @ 25-27hz and see how it comes out, hopefully this will work out VERY well, and give me exactly what i'm wanting from it. Deep extension with a very accurate low end but not at the least overbearing, to mate with my other drivers very nicely.
 

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With a box that large sealed would have low bass response as well.
I think npdang, like usual, hit it right on the head with eq'ing it regardless of enclosure.
But my preference is in line with you going to a larger box for that driver.
 
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