Sub Box wood thickness

[MG's VH Wag]

Hi guys, I have made myself a sub box for my two 1200watt subs but they don't seem to be performing as well as i would like. I was just wondering if the thickness of the sub box wood makes much of a difference. Currently the box has 6mm thick MDF of the top and bottom and 12mm MDF on the back and front. Would this be causing my subs to be under performing?

I will get a pic of my box tonight with dimensions because it is too hard for me to explain lol.

Cheers!

[acarmody]

Why did you use two different thickness MDFs? What subs are they? Pioneer, kicker, fusion, JL? Is it one single chamber twin box or two single boxes?

Depending on the answers the box may be flexing with the 6mm MDF, maybe even on the 12mm.

[cander24]

Unfortunately you've made them with mdf that is way too thin and will not resonate very well. If you want a sub box that performs well and gives a real deep bass note and resonates properly you really need to use a minimum 16mm or even 19mm is ideal. The only downside of the thicker mdf is the weight. Are you going to cover the box in carpet? If you are and you dont want to have to start again you could always try and add another 6mm thickness to the top and bottom and see if this improves it????

[MG's VH Wag]

My subs are Kenwood 1200 watt 12 inch with 400rms. The two subs are in the one box. I will get a pic tonight of it. Also it is ported.

Can i fill the box with foam or body dedener or similar?

I will most likely cover the box in carpet but i dont wanna do it yet if my box is no good lol.

[acarmody]

No foam or sound deadener won't stop the box flexing. Its the pressure that the subs are creating that makes the wood flex.

[StoneX]

18mm is the standard thickness that is generally used. I like to use 25mm or two layers of 18mm for the front baffle.

[holdenboy]

[QUOTE=MG's VH Wag;1052920]My subs are Kenwood 1200 watt 12 inch with 400rms. The two subs are in the one box. I will get a pic tonight of it. Also it is ported.QUOTE]


Mate to port a homemade box youve gotta get it right otherwise it'll sound like crap, no matter how thick the wood is. But yes, a minimum of 16mm MDF. Its also VERY important that the box is sealed properly, and dosent leak air anywhere else other than the port.

[calais_cruzin]

Ive got 2sheets of 18mm stuck togther for my box, 2cube ft box, nice n heavy 2

[VQXTC]

I would strongly suggest making a new box and using 18mm craftwood and getting the proper dimensions for the ports..... As Holden Boy said it will sound like crap..... but an experiment to try would be to temporarily seal the ports that you have created in the box. The easiest way to do this is just to screw some bits of craftwood off cuts over the ports and see if that makes much of a difference. If it does then you know that the ports are not tuned properly and consequently are one of the factors hampering the performance of your subs the other is definitely the thickness of the wood....

Hope this helps...

cheers

[MG's VH Wag]

Ok guys thanks heaps for the help. I think i will leave the box making to the pro's lol. I have a single sub box that i bought from strathfeild so i think i'll just buy another one of them and have two single boxes. I want to port the boxes so what would be the correct size hole for each box?

Here is a pic of the box i have, i will get another one of these.

Cheers!

[acarmody]

Mate you can't just cut a hole in any ol' box and make it a port. Ports have to be very specific sizes, and your subs manual should tell you what that is. Also ported boxes are bigger than sealed boxs so chances are that this box just won't cut it.

Why do you want to port them so badly?

[MG's VH Wag]

Yeah i know all that. What i was wondering is can i port this box? The reason why i want to port it is because i was told that it sounds alot better ported, is that true?

[acarmody]

No as a matter of fact bass sounds a lot tighter in a sealed box. A properly tuned box can sound as good, if you are willing to fork out hundreds of dollars. But definately stay sealed. As a simple rule, sealed is for quality and ported is for loud low bass.

Like I'm building some boxes for some Kicker L7 subs I just bought. I'm buiding some sealed boxes for everyday use and some large ported boxes for when I have some fun at comps.

[MG's VH Wag]

Ok thanks mate. I want my subs to be loud too just to show off to my mates as to who has a louder car lol. How much louder bass do you get from a ported box to a sealed box? If its not too much different i wont bother with a ported box.

[StoneX]

You need to go and do some research into ported boxes... Google will help you out there.

Porting is quite complicated... The volume of the box, the port volume (and area) and subwoofer all determine how it will sound... You can tune a ported box to be VERY loud at a small range of frequencies for competions or you can tune it for a wide range of frequencies but it will be quieter. Then you need to know what frequency to tune it for... The lower you tune it, the lower bass you get but it usually reduces the overall output of the sub. You have to compromise and generally a sealed box is a much easier and better sounding compromise than a poorly designed ported box.

Also, only certain subs can sound decent in ported boxes... Others will sound bad no matter how you design the box. You need to tell us the model number of your subs and we can find out what type of boxes they suit.

Your subs are not 1200W, that's just marketing bullshit. It'll say 300W or something in small writing on the back of the sub.

[acarmody]

That really depends on a lot of factors. Like what model Kenwoods are you using and what amp are you using to power them? Also how big of a box do you want to build? the ones I'm building for my L7s take up nearly all of my VX boot.

Also sacrificing sound quality that you would hear every day in exchange for showing off to your friends once or twice isn't really worth it.

[MG's VH Wag]

Ok yous have convinced me to stay with sealed. My subs and amp probably aren't even that good to be used in a ported box. My subs are Kenwood KFC-W3011 and it says they are 1200w (400rms) and my amp is a Kenwood KAC-8104D 1000w monoblock. They probably wouldn't be good enough to produce low bass lol.

Thanks guys you have been very helpful.

Cheers!

[acarmody]

I was having a look at Kenwood's website (goddamn the australian version is slow), and i found the specs for your woofer. Bloody helpful it was too, gave all the specs we want and even dimensions for building a ported box!!

Now that sealed box you have I'm assuming its the Aerpro box cause it looks pretty similar to mine, it's going to be 1 cubic foot. So looking at the sealed box graph the sub is going to have the best responce at about 70Hz, but your amp is way underpowering those subs so this might be different.

Now have a look at the ported box graph. Notice the spike of the 1 cubic foot box at about 75Hz. So this will be the most loudest design. It says that the port size for this size box will have to be 2.5" diametre and 7.5" length. So if your box is 1 cubic foot than that is the size port you want. So if you can get some sort of pipe (PVC??) thats 6.35cm in diametre and cut it down to 19mm and can then fit this to the box than you will have a properly ported box. It will be a nice and tight bass but will still go hard!

If anyone sees any flaws or anything with what I wrote then please correct me.

[StoneX]

That is a terribly high frequency to tune at... Ideally you want it to peak in the 30's or 40's for music, even 40's is high, in my opinion. I prefer to tune it even lower into the 20's to give that extra low bass you can only feel, but I'd sacrific output for quality anyday

[MG's VH Wag]

I was having a look at Kenwood's website (goddamn the australian version is slow), and i found the specs for your woofer. Bloody helpful it was too, gave all the specs we want and even dimensions for building a ported box!!

Now that sealed box you have I'm assuming its the Aerpro box cause it looks pretty similar to mine, it's going to be 1 cubic foot. So looking at the sealed box graph the sub is going to have the best responce at about 70Hz, but your amp is way underpowering those subs so this might be different.

Now have a look at the ported box graph. Notice the spike of the 1 cubic foot box at about 75Hz. So this will be the most loudest design. It says that the port size for this size box will have to be 2.5" diametre and 7.5" length. So if your box is 1 cubic foot than that is the size port you want. So if you can get some sort of pipe (PVC??) thats 6.35cm in diametre and cut it down to 19mm and can then fit this to the box than you will have a properly ported box. It will be a nice and tight bass but will still go hard!

If anyone sees any flaws or anything with what I wrote then please correct me.

Gee thanks mate that was very helpful. I'm just not sure on the port, are you saying i need a hole 2.5" in diametre to fit a peice of pipe with the same diametre but 7.5" long? Or can i just have a ring of pipe 6.35cm in diametre by 19mm long so it fits snug with the thickness of my wood?

Cheers mate.

[MG's VH Wag]

Just to be sure here are the dimensions of my box

Face- W 40cm, H 37cm
Side- bottom 38cm, back 29cm and the top is 25cm

I just roughly measured these to make sure the port hole is the right size for the box.

[StoneX]

Are those dimensions internal or external... You'll need to measure the internal dimensions to work out the internal volume. Once you've done that we can tell you the volume of the box and see if it's close enough to use the recommended port.

Anyway, you'd have to go to a plumbing supply place and ask for some PVC pipe nearest size pipe with a 6.35cm internal dimension, then just buy the shortest length they sell. My local Swan Plumbing place has heaps of scrap pipe laying around that they give away for nothing. Then just cut it to 19cm.

Then you'll need to find a hole saw to suit the size of pipe you got. You'll need a port for each sub.

With that tuning frequency it's still not going to sound very good.

That info says the speaker has a Qts of 1.088. A Qts of 0.30 or less suits ported, a qts or 0.30 to 0.50 suits ported or sealed, a qts of 0.50 or higher suits sealed. Your sub is a long way off suiting a ported box, that's why the frequency response graph is so bad.

[MG's VH Wag]

With that tuning frequency it's still not going to sound very good.

That info says the speaker has a Qts of 1.088. A Qts of 0.30 or less suits ported, a qts or 0.30 to 0.50 suits ported or sealed, a qts of 0.50 or higher suits sealed. Your sub is a long way off suiting a ported box, that's why the frequency response graph is so bad.

In that case i think i will stay with sealed then when i upgrade my subs hopefully in the near future i will look at a ported box etc.

Thanks for the help and your time guys much appreciated!

[StoneX]

Yeah, if you want loud subs, next time look into which brands and models will work well in ported enclosures. DD (Digital Designs) subs are well known for being loud and pretty much all suit ported boxes perfectly

[MG's VH Wag]

I finally got another sub box. I had to travel about 100km to get one exectly the same design as the one i already have from another strathfeild, my local one had none left and wasn't getting any for about 6 weeks and i wanted two exactly the same so it looks half decent. Anyway i got it all connected up and man they sound so much better than in my crappy home made box lol. I onle need to turn it up half the volume to get the same amount of bass and the bass is better quality too.