Sub Boxes

[LoonTim]

Building a sub box. Can anyone help me, give me a rough guide on what size/dimensions I should go for on a sub enclosure please?:d

Its a single sub 12" (12 1/4" to be exact). Any more info needed let me know.
The depth of the actuall sub, to the bottom of the big magnet thing is 6".
Its going in the back of a saloon so overall size not an issue.

Never done this sort of thing before and not got a clue. I'm not after a perfect mega setup and not particularly a bass junkie just want something that'll sound decent and I can turn up loud!

Many thanks.:thumb:

[LoonTim]

So I found a website called 'easy-caraudio' or similiar who show the diagrams for their 12" sub enclosures and created my own just tweaking it a little bit to my preferance.

For some reason I was working in inches...the scale is 1" = 1/4"

http://i696.photobucket.com/albums/vv327/novaloontim/S1053407.jpg

Let me know what you think and anyone who knows anything about this sorta stuff if any improvements could be made and where.:thumb:

[Southie]

Is this link any good for you? CLICKY (http://www.diysubwoofers.org/) :)

[LoonTim]

Man, thats just fried my headlol ^^^
Cheers though, very interesting. Something to think about.

[Southie]

lol How about this one then??? CLICKY (http://www.scribd.com/doc/9232046/How-To-Build-A-Subwoofer-Box) :thumb:

[LoonTim]

I knew I should have just brought a sub in a box:roll:
I'm gunna have to give this some serious thought.
Do you understand this btw mate?

To determine the box size for a sealed enclosure system, you will need to know the following Theile/Small parameters for the driver:

Vas = Equivalent air compliance (litres)
Qts = total Q of the driver at Fs
Fs = resonance frequency of the driver (Hz)

Choose a final Qtc (total Q of system at resonant frequency) for your design. Recommended values for Qtc are from 0.6 to 1.0. Transient response degrades with higher Qtc values, but the power handling of the system increases. A Qtc of 0.7 will usually give pretty good results, but you can use a higher figure if the subwoofer has a low resonant frequency (<20 Hz) or if it's being designed for car use.

I dont undersatnd the 'choose a final Qtc (total Q of system at resonant frequency)' I've got a Qts of 0.59 and a Fs of 31Hz.:confused:

[Southie]

One answer. Nope lol

Thought you did, I was just giving you guidance ;)

[LoonTim]

Fair enough. lol .
I will have to get some intelligent friends round for some maths lessons:eek:
I'm sure someone on here will understand the electrical/sound side to it.

[h9scw]

Your really looking at the Vas figure to give you an approximation of box volume. Most sub manufacturers will quote a "Vas" required to give a certain frequency at peak efficiency.
The box can be fine tuned through its volume to give different frequency responses.....for example, I have two 10" kicker solobarics which give their best sound quality when placed in a box with a volume approx 24litres, whereas, if I fitted them in a smaller volume of box they would have a greater SPL output (more boom, less "sound"). Adding a port or bandpass type box can increase both SPL and SQ (its a more efficient use of space)

[LoonTim]

Ahh ok cheers h9,
I have, and I quote 'Vas/Litre/FT3 = 113.3/4.0'
What unit will that be, its an american sub. Both those figures in litres sound wrong.
I will keep searching though see if I can find anything else.

[LoonTim]

Ok. So here is the link for the sub I have...(mine are directed electronics though not the rebranded wcc's.)

http://www.onlinecarstereo.com/CarAudio/p_16625_WestCoast_Customs_WCC-124S.aspx

[h9scw]

113.3 litres or 4cuft......if you think that sounds wrong, look at it this way....standard(ish) petrol tank holds between 50 to 60 litres, so the box is going to be approx twice this size.

113.3 litres is 0.1133 cubic metres, which is quite a large displacement, this will be to achive your low Fs of 31hz (must be a window shaker!)

If you can work out what space you have in which to build the box, then work the volume out from there to suit the sub. This looks as though its going to need a large box...a rough cube of 0.5m x 0.5m x 0.45m would have a volume of 0.1125cu m (or 112.5litres)

To add a wedge shape would require recalculating for the addition of a triangular prism.

[LoonTim]

Thats brilliant mate. Now i can get on with designing/building the boxes. Cheers. ;) :thumb:

[h9scw]

http://www.the12volt.com/caraudio/boxcalcs.asp#wed

This site is full of handy sub related info, towards the bottom of the page you'll see the volume calculations for wedge style boxes (its in inches with a cu ft result as its American) but its handy if maths isnt your thing

[LoonTim]

Now that is a handy site. And this is gunna be one big box...good job I'm only putting the one in (as i take it they need 113litres each) and selling the spare.

[LoonTim]

nother quick question,,,easy one this time,,,what thickness mdf should I use?
I was thinking 15mm.

[Jack]

I used 18mm MDF to build mine. Does the manual not tell you the ideal box capacity? [edit] Just looked, its a West Coast Customs sub. So the manual is devoid of any useful tech info I assume lol

You think you have it hard, you should see the shape of the sub box I needed to build to go in the Celica and the pages of calculations required to make it right lol

[edit again] Just tried to calculate box size on the crap data given about the sub and it came out as 167 litres lol Fcuk it, just chuck it in a standard size box and have done. I doubt a properly dimensioned box will make a blind bit of difference on that anyway.

[Sturge]

I would say you have yourself some free air subs! Directed subs are funny for box sizes anyway iirc, tend to be more for bandpass boxes. My 12" solobaric's require 1 cu.ft. boxes, which is only just bigger than the sub itself and even the big JL's only require 1.5. Sell them and buy ones designed for sealed enclosures :)

[LoonTim]

No manual razorjack, secondhand off of the ebay ,(paid 10pound for the pair and picked em up myself, in shrewsbury).
Anyway I'm just about done with measurements the saloon boots big enough so will go along the guidelines h9 gave me and build some as close to that as poss, height of boot is only 450mm not 500 but hey cba with perfection, also if i did full size there would only be 1" either side of the box to the 6x9's if you know what I mean.

[LoonTim]

How small are we talking when you say small? Perhaps it would be easier to run a more powerful 12" sub to save on space.Thing with ported boxes is that they tend to usually be bigger than sealed ones if done correctly.

Hey, what do you mean 'small'? Got it sorted now mate anyway:thumb: Cheers.