Is there an online FAQ or even good basic guideline to designing and building quality subwoofer boxes? I've read through various website and have a good basic understanding, but still have specific questions such as:

What internal shapes are good, which bad?
Does the volume of the speaker basket gets deducted from available internal space when computing the necessary box volume?
How much space is usually required between the speaker and floor to prevent contact at high volumes?
When is adding polyfill a good idea and when isn't it?
What is the recommended MDF thickness and when is it better to go thicker.
Is there a recommended glue/sealer/screw/staple/etc...


And on, and on... I like to research things as much as possible before jumping into a project. It helps keep the number of mistakes to a bare minimum.

Any links to sites/FAQs that do a good job of instructing a noob in quality subwoofer box construction would be GREATLY appreciated.

Thanks!

 

The shape of the box doesn't make a huge difference in sound. Ideally a round box is best, a perfectly square box is worst - this is because the square box will reflect the waves right back at the driver. Then you have different types sealed, ported, 5th order,

Fill is up to you, and the limits placed on the size of the box. Fill -only helps to make the box 'act' like a larger box. For example, you are limited in space so you make a small box, but like a bigger box sound, then you Want to fill... Lots of fill will give you an increase of typically 10%

When calculating box space, use internal dimensions, and YES, subtract the speaker volume from box volume.

Space to the floor is your best judgement. The surround is only going to stretch so far, and leave a little extra beyond that.

I hear Gorilla snot - or gorilla glue is the best, i've had good luck with plain old wood glue.



Wood thickness is best at 5/8's then 3/4' Don't know of any boxes with thicker wood yet. -that's using Medium Density Fiberboard - don't confuse it with particleboard.

http://www.mtxaudio.com/caraudio/edu...nstruction.cfm

 

I just got done reading the MTX link on box construction, and they suggest that filling a large box will decrease it's volume and do the opposite of what I said before...

Although... It does indicate fill will remove the bump caused by a small box - which also coincides with what I said by giving the box an impression of behaving like a larger enclosure.

I guess it works both ways...
(MECPnever metnioned the mtx version)

 

He pretty much said it.

Ive never used gorrila glue, just liquid nails everywhere, screws at least 1 5/8 inch long to get into the second board good, and then caulk all the seams/joints on the inside.

 

Box Buildin' for Dummies
http://audioforum.termpro.com/cgi-bi...c;f=8;t=014688

I read through this before I started building boxes, good stuff.

 

Just found this thread over at carsound.com. Wow! I don't know if this much info is going to clear things up or confuse me even further.

Carsound.com forum thread - Important links

 

i just went through the same thing and built my first box for my 2004 supercab. I have full drawings in 3d a full set of prints for 3 boxes now.

My first box had about 3/8" off the floor from the speaker and it was a little too close. I bumped it up to 1/2"

I used 1/2mdf and wood glue and rubberized paint on the outside for sealing and sound dampening and ot made a huge differance plus about 12oz of fill

I made mine as big as possible at 0.76" minus the woofer it is 0.5cu ft

a little small, plus my internal support i think is blocking some volume.

My new design will be right at 1.1 cuf ft and still fit under the 60% rear seat at 3/4mdf. I am getting a full 6" from the outside bottom of the 3/4" mdf to the inside top of the box. I had to route out some depth to clear the magnet

I would have just used straight cuts and nailed the box together but the odd angles to get under the seat I felt would be hard to seal. So I routed all of my pieces and they are fitted together like a puzzle. extremely tight. Then I wood glued the joints, and put a few 2" screws, then silicone the edges and finally the rubberized paint.

My new design used less drastic angles but I will still route edges for a clean fit

you can see my first box here

Car Domain Page

 

Well, after looking at various plans (none of which seemed to be what I wanted) and reading LOTS of posts/articles I decided to design and build my own dual 10" downfiring box.

In fact, I just finished it (minus the seat lift/box carpeting). It ended up giving me a net volume of .71 cubic feet per speaker, 5 1/2 inches interior depth, 52 1/2 inches wide and is only 11 1/2 inches front to back which should tuck it quite nicely under the rear seat. I have a pair of single vc 4 ohm 10" MTX 8104 powered by a 150w x 2 RMS Kenwood amp. The amp may be a bit small for the speakers, but I'll decide that after I've had a chance to play with it for awhile. I want SOME thump, but don't really need my neighbors to hear me coming home five minutes before I actually get there. I think I still have some settings to play with to get it sounding right but it is already a vast improvement in sound quality over just the 6x8 Infinity's I have in the doors.

While designing/building the enclosure, I took pics of nearly every step and of the tools/materials used. Hopefully I'll be able to make a set of plans and construction guide after it's carpeted and installed for good.

I'm sure I probably commited a few missteps along the way that experienced box builders would have avoided, but all in all I'm pleased with the way it turned out.

My thanks go to those people who posted "How to" guides and those who posted information in these and other forums. I doubt I could have built it without reading how they built theirs.

 

did you take up the whole length of the rear seat? what is the total length of the box?

11.5" that is the internal width? x 5.25 at .71X2 = 40" long box plus speakers maybe 50"

is that tapered to fit under the seat?
If not your box will stick out about 8" into the passenger leg area or basically take up the whole rear seat compartment....

If it is tapered then your box must be about 80" long?
to get 2 subs at .71cuft

 

I think you misread my dimensions. The internal height was 5 1/2", not 5 1/4". Actually, the internal height ended up being 5.6" instead of 5.5" in order to bump up the volume slightly to get it over .7 per enclosure.

I used 3/4" MDF all the way around with internal dimensions of 10" x 5.6" x 51" = 2856 cubic inches = 1.65 cubic feet. Each speaker takes up a calculated 0.11 cubic feet and the center divider/brace = 0.011 cubic feet.

So 1.65 - (0.11 x 2) - 0.011 = 1.42 cubic feet \ 2 = net volume of 0.71 cubic feet per side. And actually, 0.71 cubic feet is probably on the conservative side. Going by the MTX T8104A datasheet, the driver is either 0.11 or 0.8 cubic feet. One page lists "Speaker Displacement (Inside Box) as 3.2l (0.11 cubic feet), but on the next page it states the "Driver Volume" as 0.08 cubic feet which would give me 0.74 cubic feet per side. But as I was unsure which figure is correct, I went with the larger value (0.11 cubic feet) to make 100% sure I wasn't making the enclosure too small for the driver.

Perhaps somebody else can look at the MTX T8104A PDF Datasheet and determine which value is correct.

The box is rectangular and is not angled to meet the rear floor pan riser at the back of the cab. It is supported in the middle by the entire transmission hump as well as along both sides and a few inches at the front corners. It also leaves a total of 2" between the bottom of the box and the floor which is more than enough for speaker mounting + max excursion.

 

That makes sense but I gues you are going to bump your seat up 2"?

I made an angled box out of 1/2" mdf at 16"x8"x3.5" by 29" long for 1 sub and I have about 0.78cu ft before the sub.

My new design will still fit under the only the 60% part of the seat, out of 3/4" mdf, 5.75" mounting depth, and will by just a hair over 1 cu ft empty. I should have about .89 cu ft for 1 sub

sual vc 4ohm powerbass 350watt rms.... I am driving it right now in the old box but I screwed up and made the inner brace too big and it is acting like a bandpass.

it is TIGHT at full volume and will not distort but the volume is weak.. I will test with anew box and route out a custom brace that doesn't block any space.

I also used rubberized undercoat paint on the inside/outside to further seal the box up and it makes a HUGE differance in the sound quality.

 

I'm selling my sub enclosure plans for my 2000 F150 supercab install on eBay for $10.00 (trying to recover some of the costs to get out of the dog house with my wife ) Here's the link to my my eBay page

Mike