Building a good box for a not so good sub?

[Silentbob]

hello,

i was wondering if i could build an up to par box to help out a sub-par sub. (no pun intended)

the subs are pioneer ts-w303c's and i have two 12's in a pretty crappy box right now, i dont think its sealed properly... and inside the box, there are some sort of foam sheets? is it supposed to be in there?

these two subs are being pushed by a jl 300.2... i know the subs arent the greatest, but i'll have to do with what i have.

it says 1.5 cubic foot recommended, but i have two of these so should it be 3.0 cubic feet total?

what would be the optimum box for me to build?

here are the specs of the sub from the manufacturers website if it helps


Diamondplate Foamed IMPP (Injection Molded Polypropylene) Rigilite™ Composite Cone Woofer (Titanium Grey)
One-Piece Cone Construction for Reduced Distortion
Dual-Layer Urethane Surround
Direct-to-Cone Voice Coil Mounting Ring
Conex Damper with Damper Ring
Lead Wires Integrated into Damper for High Reliability and Improved Power Transfer
Oversized Glass-Imide Voice Coil Bobbin
Projected Pole Yoke with Vented Pole
High-Energy Strontium Magnet with Bumped Back Plate
Low-Q Design for use in Small Sealed Box (1.5 cubic foot recommended)
500 Watts Max Music Power
160 Watts Nominal Power Handling
Frequency Response: 18-2,000Hz
Sensitivity (Efficiency): 93dB (1W/1m)
4 Ohm Rated

thanks in advance

SB

-edit- how would i go about cleaning / washing the subs? they are kind of dirty... it is ok to wash the rubber surround w/ a damp cloth?

[thquack]

I recently had a to design a box 10" Sub box to fit in the back of a convertable, a very small area...

For you, you can go with either 2 boxes or one big one, whatever space allows.

First, sketch out your design, take into consideration the volume of your Subs and add that to your volume to form your 3 cubic feet box. This volume should be in your instructions or specs. You didn't list that spec.

total volume of desiged box = 3 cubic feet +(volume of Sub)*2

example
3 cubic feet + (.25 cubic feet Sub)*2 = 3.5 cubic feet= 6048 cubic inches

so lets say you want volume of 30"*15"* ?" = 6048 cubic inches
30"*15"*13.44"=6048 cubic inches

so if you used 3/4 wood you would want to over lap the ends by 3/4 of an inch so take that into consideration. It the top and bottom over lap the sides and two sides over lap the ends...

top 30.75"*15.75" w/ 2 12" holes cut out
bottom 30.75" *15".75"
long sides 30.75"*13.44"
end sides 15"*13.44"

Now that you have your design, go to your local harware store and find the thickest and heavest wood/material you can find.

I highly recomend using a table saw to cut it, you want perfectly straight and right angle cuts.

once you have all your pieces cut out, put the box together with wood glue, then you a nail gun to make sure it seals nicely, (or use finishing nails)

When the box is dry, take some silcone and cauck all the corners inside to get a nice seal. drill 2 holes for your wires and then put them in leaving engough to work with and glue them in with siclone. We are are going for an air tight box. Let dry

Paint or carpet the way you like it.

Fill the box with fiberglass insulation like you would find in your attic, place in your speakers with there seals or glue them in with silcone. Secure them with screws.

This method should give you a really hard punching bass box. You will really be able to hear the bass kick drum and all it's glory along with a nice clean bass sound. Volume may be reduced some, compared to a ported box, but the ported box will not have the hit of the sealed box.

[Silentbob]

wow... awesome thanks for the reply

by volume of sub, you mean the space it takes up when the back part is pointed towards the insides of the box? like where the magnent is?

also, what does the fiberglass material really do? is it necessary?

thanks again for the reply.

[thquack]

Volume being and don't do this, go look it up! Volume being the back part you put in the box dipped in water to see how much it will displace.

you could also get a good guess at it by going here and caculating it: http://grapevine.abe.msstate.edu/~ft.../vol/cone.html
just be sure you use your units properly there are 1728 cu inches in 1 cubic foot.

As for the filling, It helps dampen resonance in the enclosure. So you don't get extra sounds. Make sure it is loose and just full, don't pack it down! Pretend like it's insulation, cause it is.

if you have the gasket seals for the speakers, as opposed to the glue, still try it with and without, decide what you like, its your ear.

[ma1ade]

to tell if your box is sealed, when you put the subs in, push the cone in and it should take a few seconds to expand back out. If it pushes right back out then there is a leak in the box, find it and kill it. A completely air tight box will sound 100 times better than one with an air leak. Pressure = Awesome.

[svc]

I'll just add that if you're building a crazy custom shaped box, you can use packing peanuts to estimate the volume. Google is great for unit conversions, but you just put the correct volume of packing peanuts in a plastic bag and can form the shape however you want. Good luck, post some pics when you're done!

[ej20fan]

there are a few problems with the above description of building a box.

Fist, to calculate volume inside the box, refer to the owners manual, as they will often have already incorporated the displacement of the woofer. Don't just add the displacement, as in this case, the box would end up being too big, resulring in some sloppy bass. Furthermore, when two woofers share an airspace, it must be reduced by 20%, as they will shared air within the box. Simply doubling the recommended volume by 2, will again result in a box that is too large.

To add one more monkey wrench into your project, depending on what kind of amp/power your putting to these woofers will further affect dimensions. The more power, the smaller the box, as the woofer will require more resistance to play properly with heightened powerlevels. The lower the powerlevel, the larger the box, as it will need less resistance to play properly without being choked.

In regards to polyfill, it will affect the way the woofer behaves. I don't recommend, and actually avoid using it whenever possible. It is designed to work as a bandaid for a box that was not built properly, or too small, not to get rid of standing waves as someone posted. Standing waves will become a problem within the vehicle or in port design when building a vented or bandpass enclosure, not within a sealed box, as the airspace is too small, and does not take part in the generation of sound, as it would in a vented or ported box.

[thquack]

Hey check this out, pretty cool
http://www.teamswift.net/forum/viewtopic.php?t=5490
http://www.linearteam.dk/default.aspx?pageid=winisdpro

Yes, yes my math may not add up, one really needs to read the manual for there specific speaker.

I listen to mostly hard rock/metal and classical so I like my Sub to be as dead as possilbe. My box is sealed, braced and filled. Maybe I am just wierd. Years of Music Theory may have done me in.

Just like putting a pillow in your kick drum. I say try it and see what suits your tastes. It doesn't take much to put the fill in and out. It is also a 10" Sub in a 1 foot box, and thats all the room I have...

Oh and just in case you where wondering, don't waste your time hooking your stereo up to your bass guitar amp/speakers, it's not as impressive as I thought it would be. Sounded like a good idea when it shakes the house hooked up to the guitar. One would think 4 10"s and an 18 would sound cooler. Stick to the live stuff I guess... Guess I am weird!

also don't touch your cones! You know the rules about the oils in your hands! Nasty stuff! Your finger prints are there even through latex gloves!

Don't go pushing them in to test pressure, if the box is truely sealed then if you push it in, it will be under pressure and pop right back out!

If you want to dust it off, maybe try something really soft like a wool duster or syntetic static duster.