Ported Sub Box, Which type?

[Ollie SXi]

Can someone with some decent knowledge on subwoofer enclosesures just double check these figures for me....

12" Sub running at 500rms and requireing a 1.75ft3 ported ensolusre.

from what i have worked out so far, the box needs to be all right angled and of the sizes, 16"x16"x12" with a rectangle port of 6"x1".

Now can i make the porting hole simply a gap with a step back out of say MDF and build this into the design of the box... for example....

http://i65.photobucket.com/albums/h211/XtremeOllie/BoxDesign2.jpg
http://i65.photobucket.com/albums/h211/XtremeOllie/BoxDesign.jpg

which one of these box designs seems best port wise?

[Martin]

good effort, but, unfortunatly mate a port isnt just a hole... it "tunes" the box to a frequency... having the complete wrong frequency WILL damage the sub. enclosed boxes are easy, as its a simple equation. to port a box, you need to know lots of details...

have a play: http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

for SPL you want about 55hz iirc in a corsa.

but you wont want that lol

id try to get it to about 32hz... im hoping your sub tells you which size volume box you need for a ported set up...

hope that helps

[Ollie SXi]

Cheers mate, i'm not too keen on damaging a sub so ill just go for enclosed. That will probably save me a good few hours aswell.

shame that took me 2 hours of researching lol!

[mo1315]

Cheers mate, i'm not too keen on damaging a sub so ill just go for enclosed. That will probably save me a good few hours aswell.

shame that took me 2 hours of researching lol!

But I bet you learnt a fair bit in the process! If you've got the time, continue the research. A well made ported box will be much more efficient than a sealed box and its always nice to be able to say "I designed and made that from scratch!"

[Martin]

exactly, its worth the work mate ;)

[Nocky]

First of all what Driver are you using?

i will have a look on BBP6 and ile find a desired Port area and length for maximum performance!

Also is the figured above internal figures?

[Ollie SXi]

First of all what Driver are you using?

i will have a look on BBP6 and ile find a desired Port area and length for maximum performance!

Also is the figured above internal figures?

The box is already made now, its internal sizes are 16x16x12".
By driver do you mean amplifier?
Once the box is made to suit a specific subwoofer, eg. alpine SWR-1242d, does this mean no other subwoofer can be used, or is there a little give and go on the exact specifications, say replaceing the subwoofer with another one which is the same wrms and frequency?

I am makeing this for...
Subwoofer alpine swr-1242d 500rms 25-500hz
and
amplifier alpine mrp-m850 500rms at 4ohms 20-250hz

PS. is 500rms in a ported box a good system? overall it will cost about £200 i think and thats around my budget.

[Nocky]

Ok, 16x16x12 divided by 1728 gives 1.77 cuft

Other Subs (drivers will be ok in this box too.)

But you can design a cab to match the Sub almost perfect.

What size port do you have and what is the length?

I can then tell you what you are tuned too.

That specific Sub you have has an FS (natural resonant frequency) of 27hz so this is where i would tune my Cab!

Tbh the Cab is a little small for a twelve i would of put it in 2.5-3.0 cuft but if its the only space it will have to doo!

But if your port was 6x1 and 10 inches deep this would tune to 28.4hz BUT you will have port noise from 26 hz!

So the vent area needs to be bigger.


Feel free to add me to your MSN christiannock@blueyonder.co.uk

[Ollie SXi]

Cheers mate, i cant believe that actually makes sense to me!
The reason i have the cuft at 1.77 is because i made the box as square as i could so it was easier to calculate.

I could probably get the box to get up to 2.5 cft its only an extra few inches on isnt it.

I dont have any ports at all at the moment, i was just going to make a suitable one.

Is this the case or do i really need to buy one? so far the box has cost me £0.00 and i would be happy if it stayed at that.

tools/materials are not a problem i have a whole studio's worth!

[Nocky]

Dude heres a tip, Go out and buy some drain pipe lol.

Your box would be louder at 2.5 cuft but heres a pic of my mrs cab its 2.1 internal tuned to 25hz for a ten.

http://i69.photobucket.com/albums/i71/reaudio/IMAG0320.jpg

i think you could easily doo 2.5 cuft evan 3 , let me know what space you have and ile happily design you a Cab!

Its a bit ghetto but it needs covering , will do this when im not Ill!

[Ollie SXi]

OMG THATS HUGE LOL!
give me two secs im just makeing a quick scretch

[Nocky]

ok internal figures

13 inches high floor to shelf

30 inches wide width

12 inches deep bumper to back of seat

Go see if you can get these measurements (25mm mdf so take into account of size)

Then 4 inch drain pipe at 9 inches in length will give you 33hz tune if thats what your after!

This box is giving a nice flat curve acrross from 33 hz to 40 with 1.6 db diffrence so not bad at all!

[Ollie SXi]

http://i65.photobucket.com/albums/h211/XtremeOllie/untitled.jpg

Space saveing is pretty important in this install so i probably wont be able to get up that high

could go up to 14" deep (from 10") does the shape of the internal matter?

[Nocky]

What are those dimensions?
is thet the 1.77 cuft one?


4 inch port on top

15 inches long tunes to 32.35 hz


Its ok but the lower frequencies start rolling off before tuning but then cabin gain will help you.

if thats all you can do then that port will be best!

from 40hz to 33 you are loosing around 2db, but then the cabin gain will help this ,just try it and see!

Its just i can get a flatter curve with a smaller port area but you will get vent chuff!

[Ollie SXi]

What are those dimensions?
is thet the 1.77 cuft one?

sorry, those dimensions are the original box 16x16x10" internal + the space that is left, the triangle bit which is 19x17x8".

so the triangle section is 0.3935 so plus that to 1.77 and i get just over 2cuft right?

[Nocky]

those dimensions are 1.7cuft in the pic above.

that adding them together!


But if you can go 14 inches instead of ten then yes thats just over 2.5cuft.


so now you are tuned to 27 hz with that 15 inch port!

[Ollie SXi]

That will have to do then mate, as i say space is very limited as alot more is happening in the boot.

so port wise, i just need a bit of drainpipe cut to a length, how do i work that out and can that go anywhere on the box?

Cheers for all your help mate, legend :D

[Nocky]

Ok if that 10 inches can be made 14 then you have 2.53 cuft internal.

So if on top of the box you can get a 4 inch drain pipe and cut it to 15 inches long you get 27 hz tuning right by your subs FS.

the curve is now alot better on the grapth.

But make sure the Tube can be slid in and kept at least 2 inches from the box inside so you arnt blocking the port !


No problem for the help!


I dont win these for nothing lol.
its my biggest one!

http://i69.photobucket.com/albums/i71/reaudio/IMAG0348.jpg

[Ollie SXi]

Just had a look and yes i can get the depth upto 14", had a look around and ive got some 4" drainpipe.
Ill get the box built up tonight and get back to you if you dont mind.
Cheers!

[Nocky]

http://i69.photobucket.com/albums/i71/reaudio/IMAG0345.jpg

http://i69.photobucket.com/albums/i71/reaudio/IMAG0344.jpg

just an example


Yes that is fine mate.

[Nocky]

Did you sort this out Dude?

[Ollie SXi]

Yes mate, got it made up. Its pretty dam big, takes up one whole side of the boot.
Not a right lot else i can do now till i get some funds together for the sub/amp.

Gonna build up a nice enclosre for the amp on the left hand with fans concealed

[Ollie SXi]

do you think the alpine 500 rms type r sub and alpine amp are the best choices mate?

[Nocky]

What was you paying for it?

The Sub has not got much X max, The JBL Gt5 would be my choice at around 35 quid.

has more X max and a lower FS , im thinking of doing 16 10's of these in my next Install!

Only problem is , that its got a singal 4 ohm coil so finding 500wrms at 4 ohm will be expensive.

Just try out the Alpine kit mate has the box is designed around the Paremeters of that Woofer.

But for future needs the box will be ok with a diffrent sub.

[Ollie SXi]

What was you paying for it?

The Sub has not got much X max, The JBL Gt5 would be my choice at around 35 quid.

has more X max and a lower FS , im thinking of doing 16 10's of these in my next Install!

holy moly, thats alot of power, how many batteries will that need?
thats another point, do you think ill need a battery?

just had a look at the jbl gt5 but it says its only running at 275 rms, thats not a right lot is it?
What you think to the new Vibe stuff, http://caraudiosecurity.com/shop/product/products_id/7050.html

[Nocky]

It aint but its more efficiant , check the x max out over the Alpine.

The Gt5 will be better with less power than the apline with more!

They take 500 wrms easy but to get the gt5 to x max you would need to fit it in around 3cuft with 300wrms.

My mated Astra with the Wall has only 2kwrms and its doing 148.9, that is because the box is efficiant and 250wrms each they are getting is pushing the Woofers to there limits.

Also IMO Vibe suck!

[Ollie SXi]

arr right i understand.

well i guess it all goes on my budget doesnt it. The best option would be http://caraudiosecurity.com/shop/product/products_id/5932.html

But my budget is £200 next month, so i will have to see if i can get it all cheaper!

[Nocky]

My choice would be.
http://www.caraudiodirect.co.uk/alpine-mrpm650-p-5139.html?cadid=be94744e87f723bd4d33027f7d9eb44f

And two JBL gt5's.

Heres how i would install.

Its called Isobaric Compound which is this.

http://images.google.co.uk/imgres?imgurl=http://jimmyauw.com/wp-datajim/audio/52_iso.jpg&imgrefurl=http://jimmyauw.com/2006/09/19/altec-lansing-fx4021-isobaric-subwoofer-on-multimedia-speaker/&h=263&w=200&sz=16&hl=en&start=8&um=1&tbnid=3SbowZz2qU4BXM:&tbnh=112&tbnw=85&prev=/images%3Fq%3Disobaric%26svnum%3D10%26um%3D1%26hl%3 Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-GB:official%26sa%3DN

Then that amp will do 600wrms at 2 ohms.


This very basically makes the Motor strength of the two Woofers into 1 and doubles power effiancy and drops the peak.

Also doubles cone area whilst in a small enclosure!

[Ollie SXi]

Thats crazy, won't that blow the subs? faceing face to face?
That would knock that price down to about £230 aswell which im sure i could live with lol

[Nocky]

Nope because you wire the outer one out of phase!

So its Push /Pull action!

Dude get your a55 signed up on www.streetbassers.co.uk/forum if you are intrested in ICE there are some good guys on there.

Failing that If you have msn add me and ile help you out as much as i can.

[Ollie SXi]

cheers man, signing up right now :dance: