F150 Box Help!

[Hifonics]

Hello everyone,

I have a 4-door F150 and I'm looking to design a box that would sound good in the back seat. My sub is an 18" ascendant audio mayhem. Currently I have a 5.5cu/ft box behind the passenger seat. Sub forward port back. It just doesn't sound right... Not loud enough (compared to my 15" fi btl that I had... still a bit louder but not by much at all). I think the box is too small.

I was just wondering if anyone had experience building boxes for trucks or would like to help me design a box that would be very efficient for my application. I have posted my max dimensions, amp rating and my sub's T/S specs.

Thiele-Small Parameters

18"

Coils Dual 1 Ω / Dual 2 Ω

Re 0.7 Ω / 1.4 Ω

Fs 33.7 Hz / 33.2 Hz

Qms 6.52 / 6.62

Qes 0.29 / 0.27

Qts 0.28 / 0.26

Mms 307 g / 317 g

Sd 1210 cm^2

Vas 148.9 l

SPL 94.8 / 94.9 1W/1m

Bl 17.7 / 26.2 Tesla Meters

Xmax 30mm (one-way)

RMS 2500w

Amp specs: (I am running my sub at 1ohm)

RMS Power @ 4 ohms 850 watts x 1 channel RMS Power @ 2 ohms 1700 watts x 1 channel RMS Power @ 1 ohm 2600 watts x 1 channel Bridged RMS Power N/A Peak Power Output N/A

In reality I'm probably seeing closer to 2k rms unclipped power.

Max dimensions: 34H x 35.5W x 20.5D (D is for depth from front to back of the box)

Thanks in advance for anyone who wants to help me... I'll also post a build log as I do this next one.

[D-train-13k]

in truck its all about loading. i would build your box like normal and just put the sub and port facing the roof. or sub forward and port up.

[Hifonics]

Do you think I should build it bigger? Like 8cu or 10cu? I miss my honda.. was so easy to be loud.

[D-train-13k]

i would just redesign the box. do you know what kind of rise your experiencing? and what about port and sub positioning?

[Hifonics]

I'm flexible. I can position the port up and sub up, or port front sub front. I don't want to fire back again because as it stands it does not sound as good as it could sound. As for rise, I don't know what its at right now.

Edited March 13, 2012 by Hifonics

[D-train-13k]

most likely your having loading issues. my guess anyways.

most designs in trucks are port up sub up. for a standard box

[Hifonics]

ya? ok because when I first built my box I had people telling me sub forward port sideways. But I think my biggest issue is size. I think I'm choking that poor Mayhem lol. I should have built a bigger box but I was trying to keep 4 seats in the tuck... How much port per square foot should I have?

Edited March 13, 2012 by Hifonics

[Joe X]

Sub forward port back?? most likely that won't help, Here is a suggestion port/ sub firing frontwards:

Enclosure Specifications:

Fb = 33.015 Hz

Vb = 8 ft^3

External Height = 31 in

External Width = 35 in

External Depth = 20.5 in

Port Width = 4 1/4 in

Cut Sheet List:

* All Dimensions in Inches.

* Wood Thickness is 3/4 for all Parts.

External Enclosure Parts:

Front = 30 x 29 1/2

Front Internal = 28 1/2 x 29 1/2

Back = 35 x 29 1/2

Left & Right Sides:

Side 1 = 19 x 29 1/2

Side 2 = 19 3/4 x 29 1/2

Top & Bottom = 35 x 20 1/2

L Port Internal Assembly Parts:

Front to Back = 14 3/4 x 29 1/2

Extension = 7 x 29 1/2

Assembly guide on actual dimensions, port optimizations and suggested bracing:

You should have at least 4 inches of free airspace in front of the port.

Also 2.6KW calls for a solid electrical, that alone can reduce your output so look into that as well.

Let me know any questions/comments.

Edited March 15, 2012 by Joe X

[Hifonics]

Sub forward port back?? most likely that won't help, Here is a suggestion port/ sub firing frontwards: Enclosure Specifications: Fb = 35 Hz Vb = 8.098 ft^3 External Height = 34 in External Width = 31.25 in External Depth = 20.75 in Port Width = 4 in Cut Sheet List: * All Dimensions in Inches. * Wood Thickness is 3/4 for all Parts. External Enclosure Parts: Front = 26 1/2 x 32 1/2 Front Internal = 25 x 32 1/2 Back = 31 1/4 x 32 1/2 Left & Right Sides: Side 1 = 19 1/4 x 32 1/2 Side 2 = 20 x 32 1/2 Top & Bottom = 31 1/4 x 20 3/4 L Port Internal Assembly Parts: Front to Back = 15 1/4 x 32 1/2 Extension = 3 1/4 x 32 1/2 Assembly guide (generic dimensions): Left 0.05 cubic feet for bracing do some top to bottom and front to back cross bracing with dowel rods, port optimizations as well if you have the tools. Also 2.6KW calls for a solid electrical, that alone can reduce your output so look into that as well. Let me know any questions/comments.

Thank you so much man! It looks really good! The extension you have written as 3 1/4 x 32 1/2. Is that a typo?

[Joe X]

No, bear in mind that the pic is of generic dimensions, if you reaaly need a customized sketchup let me know.