View Full Version : Down Firing box ideas

08-13-2012, 02:42 PM
First post here! Couldn't really get a good answer anywhere else so ima try here. Is porting a down firing box a bad idea? I'm trying to come up with a design for a box in my jeep and for security reasons i would like to make a down firing box. The Sub i have though is a 10" L7 and I would prefer it be in a ported box. So, would a slot ported down firing box sound ok? If you think there would be to much port noise would it help to make the port face outward toward the back window? Any help will be appreciated.

08-14-2012, 07:29 PM
if your going to do a down firing box . i would recommend sub faced towards the carpet and port faced towards the trunk/hatch . hope i could help

08-14-2012, 08:55 PM
Thanks for the reply. That's actually the design i'm working with. Just wanted to get some opinions first.

Moble Enclosurs
08-14-2012, 10:18 PM
You can utilize the flooring of the vehicle to act as part of the port for loading purposes if you need to. So, if you have a down-fire design that has a port facing the rear, you may not be able to use that for extended low end, even with the placement. Better to face the port down and do a tapered port with equal cross-section (averaged) to that of a constant port area for a similar response, and have it open up TO the rear of the vehicle. So, driver AND port facing down will work well as long as there are no major obstructions in the way and you allow enough room for driver excursion. Also, the front of the "down fire" are should be sealed off by 3 bounding walls for controlling any unnecessary cancellation issues. Let the vehicle control the low end by loading and the sub to be controlled by a moderate tuning, considering it is an 87 jeep. Hope that helps

08-15-2012, 08:13 AM
Haha it is in fact a 87 Jeep Cherokee. Bear with me here please, being 18 and only have basic car audio knowledge some things are hard to understand. Now, you say it's better to have a tapered port facing down and have it open to the rear. Correct? Iv'e never built a box and my tools are limited so this seems difficult for a novice like myself. That being said, does the port have to open to the rear like that? I was planning on building a simple slot ported enclosure with either the port facing down on the same plane as the sub OR facing toward the rear of the Jeep. You say that I may not have extended low end if I face toward the rear though. Here's the million dollar question: Will having a regular slot port facing the floor sound like shat? Even if I make the legs on the enclosure like 3 1/2 or 4 inches off the floor? Or would having the port face toward the rear completely sound like shat? Thanks guys

Moble Enclosurs
08-15-2012, 10:34 PM
No problem man. We all have to start somewhere. To put it simple, the actual placement will depend on the design information AFTER it is calculated, unless YOU already have a personal preference, in which the design will be made around that if possible. It can very well be proven that a top firing design may work best----never can tell until its either tested in the real world, or at the least calculated for each scenario to show the pros and cons of each placement. The idea of using the floor as part of the port is no different, physically, than a bottom port/rear firing design anyhow, BUT with the ability to use more than a constant cross-section for higher pressure at the end of the port-rear of the box...and a small bit more of dampening depending on the floor material, such as carpet and such. Email me and Ill show you some ideas :D.

Moble Enclosurs
08-15-2012, 10:36 PM
The tapered idea I mentioned is very simple in fact. Again, my email is in my sig so give me a shout and Ill show you visually what I mean and explain more a bit in detail of the advantages and disadvantages of the layout I mentioned will likely work well. :D

08-16-2012, 09:10 AM
Thanks! Email sent.

Moble Enclosurs
08-16-2012, 04:10 PM
Thanks man. Ill be looking at it later today then! Talk to you soon!