I just got these 2 fosgate HX2 subs in a box. Its a sealed box and was told they might "bottom out" (whatever the hell that means),but im assuming it means the box will limit the deepness of the bass? Anyways its a smallish box with not alot of wood to work with around the speaker. I was wondering if I can do some half ass port job on it, if so how would I go about it. I dont need anything pretty because i still use the cargo area and its gonna get crap thrown on it or crammed against it. Just to add some bump in the trunk. Heres a picture. Also I will be using the amp on top of it. 900 watt fosgate Punch 301m.
No, you can't. The proper ported box is generally about double the size of its sealed counterpart. Just stuffing some ports in that box would result in a nasty alignment (poor frequency response characteristics).
"Bottoming out" means the box is allowing the speakers to over-extend past their maximum excursion limits (xmech) and either 1) bottoming the voice coil against the backplate, or 2) bottoming out the soft suspension parts against themselves or the frame... either way spells damage to the driver.
Bottoming out is caused by the enclosure not allowing enough 'air cushion' behind the driver. As the cone moves in and out, it changes air pressure inside the box. When the cone moves out, the air molecules in the box expand (same amount of air, slightly more volume to displace) and a low pressure region is created. When the cone moves in, the air molecules are compressed, and the opposite is achieved.
Now knowing this, consider what happens if we have a larger box as compared to a smaller box (otherwise same speaker, same amp, etc). The smaller box has less air molecules to compress, creating more resistance to the cone moving in than does the larger box. Cone moves same amount... or tries to, fewer air molecules to compress, each air molecule must be compressed more to achieve same amount of cone motion.
So this means your sealed box is allowing your speakers' cones to move too much. There are two ways to change that... decrease internal volume of the box (remake it, or put wood inside it to alter its internal size), or decrease power going to the speakers (turn down the gains on your amp).
Enclosure volume also affects over all system frequency response. A bigger box will increase low-end response, while a smaller box will tend to limit low-end response while boosting upper-bass freqs. If I were you, I wouldn't guess. Calculate your box's INTERNAL volume, should be pretty easy using a simple tape measure. Then give Rockford Fosgate a call and ask them their sealed box recommendations for your model subs. This should give you an idea what you need to do. If the box is too big, alter it as said above. If its within their specs, just turn down the amp.
