Down vs Forward Firing Subs? [2 12's under ext cab back seat]

[boy&hisdogs]

I'm looking to add a 2nd subwoofer to my current setup and will be building my own enclosure this time instead of buying one. The plan is to build a single sealed box with a divider, thus creating two independent chambers. The goal is .9 cubic feet per chamber, as this is the manufacturer spec ideal gross volume for the subs, and should run the whole with of the interior and take up the entire space under the back seat. The subs will be wired parallel.

I have a downfiring sealed box that goes under the back seat on the drivers side. I did a quick, very un-scientific test on the way home from work today. I drove for a bit, then stopped and flipped the seat up and box upside down, it ended up sitting so that the sub was facing up at about a 45 degree angle, pointing at the back of my head, drove for a while, then flipped it back.

The box in the down-firing position seemed to hit harder. Not that it was louder to my ear necessarily, but I could feel it through the floor and the seat and arm rest better. This actually surprised me as the sub only has a couple inches of clearance against the floor, I always wondered if it was enough air to push. Is this typical? Any ideas why this happens? Is there a method for maximizing the ambient, "felt more than heard" effect? ? I listen to a lot of rap, EDM and punk rock, I like when those kick drums feel like they're actually kicking the back of my seat.

Sticking with down-fire makes more logistical sense for me (protects subs and would be less complicated to design and build) but if something else would sound better then I could make it work. What do you guys think? Please chime in with anything you've got, experiences, ideas, tips, stories, bench racing, anything. Thanks for reading.

The truck is a 98 K1500 with an ext. cab and front 60/40 bench (so no center console enclosure).

 

[df2x4]

IMO it really doesn't matter much as long as you have the proper air to move in front of the cone. A couple inches between the sub and the floor would bug me. That's not a lot of room. Unless you've got grilles over the subs then anything that slides under there could be a potential disaster, plus I have a feeling you might be introducing some distortion. I try to shoot for no less than 4" or so in front of my drivers.

 

[michael hurd]

If you want to feel more, consider using something like the Aura Bass shaker:

http://www.parts-express.com/aurasound-ast-2b-4-pro-bass-shaker-tactile-transducer--299-028

It's a bit tight under the seat, but if you can fab up a bracket that is solidly attached to the seat base riser, one per side should ought to do you. I have 4 on a loveseat in push pull configuration driven off one side of an amplifier that is rated to 900 watts into the single 4 ohm load.

When the levels are set correctly ( I use digital signal processing ) the effect is fantastic.

 

[77Concours]

The down firing boxes do hit harder. A friend of mine had a '99 (800 I know) extended cab and had a down firing subwoofer box. It had 2 12's and it fit under the rear seat which gives more leg room than a front firing box (I'll get there in a second).

In my '95 extended cab I had a front firing box with 2 12" Kicker CVX which is the same exact setup in my 2003. It didn't hit as hard as the subwoofers in the '99 but sounded a lot clearer and less distorted when the bass hit. I like having the "thump" but also enjoy hearing the lyrics. BUT, I lost 95% of the leg room in both of my trucks with front firing boxes. If you don't have kids, or need the floor in the rear of your truck a lot a front firing box is great. Now if I had to choose between a front firing or down firing box again, it would be a down firing box for me. I don't have kids or need the backseat but it sucks when you can't take more than 1 person in your truck. Below are pictures of the boxes in my '95 and '03.

If you decide not to build your box for whatever reason give www.caraudiofactory.com a try. That's where purchased the box for my 1995 and 2003 Silverados. High quality and the fit is great. Prices aren't terrible either.

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[boy&hisdogs]

IMO it really doesn't matter much as long as you have the proper air to move in front of the cone. A couple inches between the sub and the floor would bug me. That's not a lot of room. Unless you've got grilles over the subs then anything that slides under there could be a potential disaster, plus I have a feeling you might be introducing some distortion. I try to shoot for no less than 4" or so in front of my drivers.

I was planning on putting grilles not over the speakers but over the ports/vents/spaces that lead underneath the box. That way not only will it protect the speakers, but keep stuff from sliding under there all together. How hard is it to lift the seat in the later 400s? It looks like it pivots on the wall and doesn't have legs/feet like in the earlier interior.

If you decide not to build your box for whatever reason give www.caraudiofactory.com a try. That's where purchased the box for my 1995 and 2003 Silverados. High quality and the fit is great. Prices aren't terrible either.

Their 2-12 downfiring box looks pretty good, and for 99 bucks that's pretty hard to argue with. Air space is nearly dead on, it's 1.0 cu ft per side in that box, Alpine recommends .9 (ideal) for my sub. The last box I bought wasn't tall enough though, had I not put extra little blocks under it the sub would be hitting the floor as it played.

If you want to feel more, consider using something like the Aura Bass shaker:

http://www.parts-express.com/aurasound-ast-2b-4-pro-bass-shaker-tactile-transducer--299-028

It's a bit tight under the seat, but if you can fab up a bracket that is solidly attached to the seat base riser, one per side should ought to do you. I have 4 on a loveseat in push pull configuration driven off one side of an amplifier that is rated to 900 watts into the single 4 ohm load.

When the levels are set correctly ( I use digital signal processing ) the effect is fantastic.

That thing looks pretty sweet, and as cheap as they are it just might be worth trying. How strong are they? I know that's a hard thing to quantify but would you call it subtle? clearly noticeable? Makes you jump out of your seat if you're not expecting it?

 

[michael hurd]

How strong are they? Well as transducers go, they don't have a lot of force. The drive level should be tailored so that they are a very subtle addition, and not overpowering. They would never replace a subwoofer, but they do a great job in augmenting them.

 

[michael hurd]

Loveseat. $ 60 used on local trader.

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View from under the footrest - with back reclined.

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Tipped over to show push pull. ( shakers on top are wired in reverse polarity )

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Driven off this:

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In my case, I am sitting 23 feet away from the main subs, and needed to add 23 msec delay on the shakers, so that the sound from the subs arrive at my ears at the same time as you feel the Aura bass shakers.

In the small area of a pickup, it won't be an issue. When balanced correctly the effect should be seamless.

 

[michael hurd]

If you are want to lift the rear seat, you can do that with longer bolts and a piece of flat bar with two holes drilled in it, one for each side. I wouldn't lift it much, if you actually plan to use the backseat for transporting people. Maybe 3/8" or so.

The square aluminum mounts the rear seat bolt to on each side are part of a bracket that bolts to the floor. Remove the bolts, space up the bracket with flat bar, install new longer bolts.