15" xfl Trunk install opinions.

[rickymac21 10+ year member]

Well after four years of no bass I'm returning to the playing fields. All the information you may need is listed below.

I already have ideas for designing this box. But my biggest pet peeve when it comes to trunk installs is trunk rattle. Plus I feel like you lose db's by having that issue. So my idea was to do as most people do and seal the subs/box from the trunk. Only problem is my seats don't fold down so I can't really build a successful half wall... So here's what I came up with.

Exterior Dimensions:

30"W x 14" H x 26" D

And using 1" thick MDF the interior dimensions would be...

28"W x 12.25" H (bottom plate will only be 3/4") x 24" D

This should give me roughly 4.76 cubes before displacement of sub/aeroport and bracing. Figured I'll end up with around 4.25 cubes after displacement but I haven't accurately calculated that. The port will most likely be 6" aero which will give me about 6.6 sq in per cubic ft (28.26 sq in total). A little low but I'd rather have 1 6" and be there than 1 8" and be at 50 sq in. Could do 3 4" but I think 1 port would be more efficient for air flow.....

Anyways. The sub will be on top of the box firing up in the trunk. The port will be partially external firing up like the sub. This is because I'd like to cut a hole in the rear dash and have the port "exhausting" or firing into the passenger/cabin area directly....

Now the tricky part would be stopping the trunk rattle... I will more than likely have seal it off like most trunk walls, only from the reverse side of the box, if that makes sense... Basically where the trunk lid (the part that actually pops up) pivits, I will have to build a wall straight down on top and around the box. taking this wall all the way to the sides, top, bottom of the trunk (right before the trunk lid opening) should hopefully create a strong enough barrier to prevent any lost db's.

It's rather hard to explain in words so I am sorry... But if you were creative enough to paint a mental picture of what I had in mind, what are your opinions on this? Do I have any other options for max output.

Vehicle : 2002 BMW 325i

Location in the vehicle: Trunk

Space available (Length x Width x Height): 27" L x 35" W x 17" H

Subwoofer make and model: American Bass xfl 15

Subwoofer Size: 15"

Number of Subwoofers: 1

Type of Port (Kerfed, Slot, Aero, etc.): Aero

SPL or Everyday Music?: Daily Driver

Tuning Freq (Hz): 32-36

Amplifier: Hifonics brx2400

Car electrical information:

-Stock 120a alt

-Big 3 w/0 gauge will be done

-Stock battery with a secondary battery.

Click to read more...

 

[Side Show 10+ year member]

does the back seat/seats fold down?

 

[rickymac21 10+ year member]

does the back seat/seats fold down?

No. Otherwise I would just do a 'trunk wall' like most people.

 

[rickymac21 10+ year member]

Morning bump. . . Just anxious to hear some opinions

 

[NASTY08IMPALA 5,000+ posts]

Morning bump. . . Just anxious to hear some opinions

Do u have the fold down rear ski hole in the center of seats like some bimmers? if so port it through there or.the rear deck or results will be diminished

 

[bmk6795 10+ year member]

is it just me or does 6.6 sq in of port area per cube seem really small?

 

[rickymac21 10+ year member]

Do u have the fold down rear ski hole in the center of seats like some bimmers? if so port it through there or.the rear deck or results will be diminished

I have a fold down arm rest, but no ski hole. It's just metal. I guess I could cut a hole there but I think through the rear deck/dash would look better/ less noticeable.

 

[rickymac21 10+ year member]

is it just me or does 6.6 sq in of port area per cube seem really small?

Yea it is. But like I said I'd rather have 1 6" port than 3 4". If I can get/ make 7" that would be perfect. I don't think they make 7" PVC

 

[Buck 5,000+ posts]

It's going to rattle no matter what. It's pressurization, it's non-directional (omnidirectional) so firing in certain directions in the trunk isn't really going to do much, all of your bass originates in the trunk and therefore pressurizes it no matter of the direction. I would do sub up and port rear passenger side.

 

---------- Post added at 10:51 AM ---------- Previous post was at 10:51 AM ----------

 

Loading off the rear of the trunk is better IMO.

 

---------- Post added at 10:52 AM ---------- Previous post was at 10:51 AM ----------

 

6" aero and 4.25 cubes will work well, no need for 1" mdf. Use .75" and gain airspace.

 

[rickymac21 10+ year member]

It's going to rattle no matter what. It's pressurization, it's non-directional (omnidirectional) so firing in certain directions in the trunk isn't really going to do much, all of your bass originates in the trunk and therefore pressurizes it no matter of the direction. I would do sub up and port rear passenger side. 

---------- Post added at 10:51 AM ---------- Previous post was at 10:51 AM ----------

 

 

Loading off the rear of the trunk is better IMO.

 

---------- Post added at 10:52 AM ---------- Previous post was at 10:51 AM ----------

 

6" aero and 4.25 cubes will work well, no need for 1" mdf. Use .75" and gain airspace.

Well I understand the pressurization is originating from the trunk in a normal trunk install. But let me say this.

Forget everything I said before.

If someone were to build a sturdy wall (no box yet, just a wall) right at the trunk lid trim/opening. This wall would stretch from the floor-ceiling and side to side. Sealing the edges with spray foam or whatever other kind of sealant. So basically this would create a second trunk space that isn't exposed to the trunk lid.

Now if you put a sub within the sealed wall area of te trunk it would have to reduce trunk rattle and increase reverberations due to a sturdy wall to reflect off of. Plus if the port is firing air directly into the cabin it would help direct the sound right? I just feel the wall will reduce the rattle and in turn increase pressure/db's.

 

[09civic 5,000+ posts]

No. Otherwise I would just do a 'trunk wall' like most people.

Rarely is it louder firing into the cabin vs. firing towards the trunk.

 

[rickymac21 10+ year member]

Rarely is it louder firing into the cabin vs. firing towards the trunk.

Your the second one to say this. So maybe my theory is wrong. If firing towards the rear is just as loud I might as well save me the trouble of cutting holes in my rear dash.

So sub up port back then?

 

[97maxima 10+ year member]

Rarely is it louder firing into the cabin vs. firing towards the trunk.

Too many variables, this statement is pretty far from the truth.

1 6in port is not enough for that sub, id run 2 6in. 3.25-4 cubes. But with the power you running id stay around 3.5 with running near double the rms. Those coils have their limits

 

[rickymac21 10+ year member]

Too many variables, this statement is pretty far from the truth.
1 6in port is not enough for that sub, id run 2 6in. 3.25-4 cubes. But with the power you running id stay around 3.5 with running near double the rms. Those coils have their limits

2 6" ports for 4 cubes is almost double the average 8 sq in per cubic ft. But as far as the power issue, I've been told the Cfl's can handle 1800w Rms all day. So why couldn't I just wire it to 1 ohm and set the gain lower on the amp? This would help prevent clipping as well.

 

[09civic 5,000+ posts]

Your the second one to say this. So maybe my theory is wrong. If firing towards the rear is just as loud I might as well save me the trouble of cutting holes in my rear dash.
So sub up port back then?

Port firing into the cabin, sub back.