Do downfiring subs need breathing room?

[Alter Ego Trip 10+ year member]

I don't exactly know how to explain this but here goes. I'm mounting 2 RE SE12's under the back seat of my Chevy. Obviously the subs are going to be mounted high enough above the floor to allow excursion without contact. I'm wondering about walling in the sides of the box though. Do I need to leave a gap on the sides of the box to allow venting, or can the sides be flush against the floor?

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[mazdakid 5,000+ posts]

Id atleast leave the front and maybe the back open and just have the mounting feet on the sides. Youd probably lose alot of bass if it was flush on all sides.

 

[Slammer 10+ year member]

X2 on leaving a gap. Not having any breathing room around the base of the box would be like putting a pillow over a speaker. While it wont take a LOT of room for the sound to resonate out from under the box, it does need some. I ran a downfiring box in my '02 Sierra and eventually ended up propping the front of the box up with a couple of blocks of wood. There were slots around the box, but I found that the increase in the opening made the subs louder. Ended up going away from the down firing and got MUCH louder, but I remember when my subs used to fit under the seat and that did have it's benefits.

 

[smgreen20 10+ year member]

I've done 7 different boxes in my Y2K GMC Sierra ext cab Z71 and it didn't make a bit of difference if it was flush or not, though I did have the rear of the box open so it was vented in that manner on the one down firing box I built. I hated the down firing box. Shook the hell out of the truck for no gain in output.

 

[Slammer 10+ year member]

Probably made a bigger difference in the downfiring box I had, because it was sealed. I doubt there would be a great deal of diff in a vented box. I know that I had one of my buds hold the box up at different angles while I had the hu cranked. Big difference with each adjustment. Last sealed box I ever owned........ As for shaking the truck, f*** yeh. Felt like the back bumper would shake off. That was cool, but the volume is much better.

 

[Alter Ego Trip 10+ year member]

I hated the down firing box. Shook the hell out of the truck for no gain in output.

That's exactly what I don't want. I've heard mixed feelings on the downfiring. Some say it increases output, which I could care less about. This setup is designed more around SQ. Should I go with a top firing design instead? I really can't go front firing without really raising the back seat. I'm raising it 2" as it is, and this still won't give me enough room to fire forward.

 

[SWFL 10+ year member]

fire up

 

[blazeplacid 10+ year member]

for sq id say down firing is the worst

it does make the sub seem louder because of the excess vibrations of down firing

 

[Slammer 10+ year member]

Are you planning on having people sit back there with the box in? If so, what type of subs are you gonna run and what is their mounting depth. My downfiring box worked okay for the Memphis PRs I had at the time, but when I went to a pair of RF P312s, the mounting depth wouldn't allow them to fit in the box. I was afraid of going upfiring and having the subs exposed to the underside of the seat (with anyone sitting there). I run big boxes now and keep my seat flipped up. If you go upfiring and have the seat down, make sure you have the necessary clearance.

 

[Alter Ego Trip 10+ year member]

I rarely ride people in the back seat. If I need the room I take the car. I almost though about removing it but I'm trying to keep with the stealth look. The box I was building for downfiring the subs had the subs flush mounted 1.5" inside the box to avoid contacting the floor. If I went upfiring I would just reverse it, so even if the seat was down or had passengers, the subs would have enough room.

To answer your other question, the seat has been raised 2" to allow enough depth to fit the subs.

Thanks guys, upfiring it is.

 

[Lakota 5,000+ posts]

Eh, depends. I've had subs really close to solid objects before and it didn't make a difference on the ol' Termlab.

 

[jdc753 10+ year member]

I am pretty happy with my downfiring setup. Granted its not an output monster but I don't have too much vibrations going on even when it is at full tilt.

I remember reading somewhere on here a rule of thumb of keeping the sub about 1/4" of its diameter off the floor. This is what I started with leaving about 3" off the floor and having 3 legs around the box sealing it to the floor and basically making it so there is only one point source to hear the bass coming from.

 

[Alter Ego Trip 10+ year member]

I remember reading somewhere on here a rule of thumb of keeping the sub about 1/4" of its diameter off the floor. This is what I started with leaving about 3" off the floor and having 3 legs around the box sealing it to the floor and basically making it so there is only one point source to hear the bass coming from.

Only problem is I'm obviously limited on space as it is. If I had to give up another 1.5" I'd really have a problem with getting enough air space. Right now, moving the sub 1.5" off the floor, I can just squeeze 1.0 cf per sub after displacement which is the ideal cf for 12" SE's. So it really looks like upfiring is the ideal way to go. I'm not too worried about total output as the two SE12's will be running 700 watts each. My previous sub was a 10" Boston G2 running 300 watt's and I was OK with it. As long as the front stage is overkill I'm good to go. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif