Dual SA-12 Low tuning questions

[ChrispyShimp]

I'm roughing out a box for a friend's build in a few months, the idea is to have two Sundown Audio SA-12 DCV4 at 1 ohm on a Hifonics BRX2400.1 in a ported box tuned somewhere in the 25-30 hz range, I'm thinking 27hz if you want a specific number. We will use a fiberglass re-enforced 8" concrete pillar tube on a removable plate so we can adjust the tuning if he chooses so. He wants the tube to be internal, and I'm wondering what cubic feet internal volume would help these subs thump the lows with the most authority.

The vehicle is a 2012 Hyundai accent 4-door hatchback, and the goal is massive lows, and a hair trick if possible. Box volume before displacements can go up to 6.8 cubes without an weird offset in the enclosure. We do not have to use all this space, I just want to know what internal volume would yield the most output on the lows

Also, if some one could elaborate on the relation between internal volume and how that affects the tuning, I'd be delighted!

Many thanks.

[ToNasty]

To low for that sub. I'd go 32-34

[ChrispyShimp]

Too low? I didn't know you could tune too low, could you educate me a little more? would the subs be unloading too much?

Because of the power, should they be tuned higher than he wanted because they subs need to load more? I'm not sure here.

[thefourth]

Tuning that low your going to loose alot of higher end output

[ChevyBoy95]

tuning below 30 is pointless imo.

you dont have to tune to 25 to play 25hz. You can tune to 35 and with a proper design play from 25hz to about 60hz and be musical, rather than having no upper end.

and most likely you wont be moving near enough air to do a "hairtrick". You might be able to move some hair, but not do a hairtrick.

[ChrispyShimp]

Thanks guys, but my original question remains, how much room should I give two of them for 33-35 hz?

Do I go by the recommended 2 cubes each for 4 net int vol or give them a tad more?

We can also go to dual 6" aero ports or a slot port, there's plenty of time to get the design right

for what he wants, and I want him to try an inverse mount, so what would be a comfortable airspace for these two?

[Dude2800]

From my experience the larger the box the closer it peaks to tuning. Which means if you have a large box tuned to 26 hz it will play 26-30 well but fall off at the upper sub frequencies. If you build a smaller box tuned low it will peak at a higher frequency. I would suggest downloading something like winisd and running the numbers and you can kind of get an idea of what your output will be.

[Dude2800]

Sundown site recommends 1.5-2 cubes each tuned to 35hz.

[ToNasty]

3.5-3.8 cubes with a single 6" aero

[jarrius]

I would say yes go with recommended box size