box help

[garfa]

hi all,
i am getting a couple of jaycars carbon 12 inch subs.
but my problem is i have zero idea how to design a box from the TS specs.
so i was thinking of a rectangular box with a sloped front.
would anyone be able to help me?
the volume is not a huge problem, so therefore the low it can go the better (~40hz).
cheers all, garth.
edit: i am trying to use win isd but i seem ot be missing some TS specs.... ahhhhhh:b: :b: :b:

[semi]

I dont know hte actual calculations, but if you google 'sub box calculator' theres a calc where you enter the TS specs and it gives you a ported and sealed sixe, as well as wether the box is suited to ported or sealed best

[garfa]

yeah i tried, but i dont read french! well all the stuff made as much sence as french or any other language i dont speak would....

[ascension24]

You dont need all the specs to use win ISD, because some of the specs are worked out from the others.

Read the help manual, takes a while to understand but very helpfull when you get the jist of it.

Ask the guys at jaycar, they should know what size to make the box anyways.

[phree]

Great fun designing sub enclosures. Just a few questions.

What type of music do you mainly listen to?

Do you want max SQ, hair shaking SPL or something in between?

How much boot space do you want to give up?

Just doing some initial modeling, 2 cuft (56.6 l) net per sub @ 35 Hz would be a good all rounder. 4.5 cubes roughly gross size is big though!

Do you want metric or imperial measurements?

Cheers

[garfa]

well i definately want SQ, my system is built around that so its sealed for sure. plus i dont want a ported box. been there done that! half the reason i chose to run the jaycars in a pair is for better SQ. but i dont want the thing to have SFA spl either. so if there was a scale with 1 being SQ and 10 SPL then i would go for a 2 or 3.
from my limited knowlage, as the box gets larger the lowest possible frequency goes down, correct?
so i would want metric measurements. the TS specs are on the jaycar site
thank you soooo much!

[phree]

At the risk of starting a flame war, which i'm certainly not trying to do. For SQ, why don't you get one good sub instead of two average ones?....Ducks and hides..
Had to get that off my chest lol.
Really though, they suit ported boxes better according to the ts specs. They will play much lower and louder while still being fairly accurate.

Anyway, for a sealed box to suit SQ, try about 43 l each net.

How are you powering them? If one amp for both, then i would recommend a shared box. So make it ~90 l gross to take into account the driver displacement, assuming they will be mounted normally and not inverted.

That should play reasonably well down to ~35-40hz.

If you give me a couple of box dimensions i.e. height and width, i can work out the missing ones for you if you like.

Cheers

EDIT: BTW, yes the bigger you make the box the slower the drop off in frequency response, however it starts dropping sooner. Mechanical power handling also drops as the box gets bigger. So it's always a compromise.

[StoneX]

Generally with sealed boxes, the more volume you have, the flatter the frequency response gets, so you'll get more low end. But there are drawbacks to that, like reduced power handling as the cone will move more freely. I think cheaper subs seem less responsive in larger boxes due to less air suspension from the box.

I replied in your other thread earlier, but I think you're best building a temporary box the size that Jaycar recommend then varying the internal volume from there until you get the sound you like. Then build a permanent box the size that sounded best to you.

[azzfox]

at the bottom of the 12" Carbon subs page on the jaycar site, there is a compressed folder with graphs and other specs taken from WinISD and it says a 27.0l box for sealed applications.

or just get it here> CS-2279.zip

[phree]

Yep, however it limits the low end extension. garfa wants it to play usefully down further than ~ 50 hz.

[garfa]

At the risk of starting a flame war, which i'm certainly not trying to do. For SQ, why don't you get one good sub instead of two average ones?....Ducks and hides..
Had to get that off my chest lol.
Really though, they suit ported boxes better according to the ts specs. They will play much lower and louder while still being fairly accurate.

Anyway, for a sealed box to suit SQ, try about 43 l each net.

How are you powering them? If one amp for both, then i would recommend a shared box. So make it ~90 l gross to take into account the driver displacement, assuming they will be mounted normally and not inverted.

That should play reasonably well down to ~35-40hz.

If you give me a couple of box dimensions i.e. height and width, i can work out the missing ones for you if you like.

Cheers

EDIT: BTW, yes the bigger you make the box the slower the drop off in frequency response, however it starts dropping sooner. Mechanical power handling also drops as the box gets bigger. So it's always a compromise.

well the reason i got 2 jaycars is because it was either those 2 or one nak 12 inch for around $400 ( and i would have run running 2 nak woofers. when its in stock! dont know how long that would take). i mean for $300 for those 2 subs i really doubt unless i spent over $550 plus i will get anything near the jaycars.
ok they are being powered by one amp. they will be wired down to 1 ohm.
stone, sorry i thought i replied to you. how will i vary the volume of the box easily?
also would someone be able to post a profile of the jaycar sub for win ISD? i just cant seem to get the thing to work!

[StoneX]

Make a temp box larger than required, then add blocks of wood over days/weeks until the box sounds how you want it. Then measure the dimensions of the blocks of wood and work out how much volume it took up and calculate what size box you need. Build the correct sized box for permanent install or just use the oversized box with blocks of wood secured inside.

[phree]

Heres a basic one of three different setups. Jaycar recommended sealed 27l/sub, 43l/sub and a ported one to compare. These are transfer function graphs. Don't have time to do any more at the moment, have to go out.

OOPs it didn't come out, bugger will try again later sorry!

[garfa]

yeh i finally got win ISD to work.
damn, soo many options...
i was thinking about this one i have attached.
the box size and port are wrong(i would prefer a slot port) but what will the problem with this box be?
thanks heaps guys this means heaps!

[StoneX]

Didn't you want a sealed enclosure? The specs might say it suis ported, but it can still sound good in a sealed box and will most likely give the sound you're after, whereas ported is alot harder to get to sound right. If you do go ahead with the ported, make sure the group delay is very low. All ported boxes i've made have been quite laggy because small volume and ported don't go well together.

[Tasmaniak]

Garth, I'm going to try and send you a copy BassBoxPro soon.....that should help you out as well.

[stocky]

i bought a sub from jaycar and made my own box for it. i took all the data they gave me and entered it into this program - http://www.linearteam.dk/default.aspx?pageid=winisd
it was a 26 litre box

[garfa]

stone: yeah its just thats F curve of a ported box got me all excited! yes i think sealed will be the way to go.
too many choices. stone if i went sealed (with out trying varying the box volume) what size would you recommend? same thing for you ray. what do you think?
i dont have the time or currently want to be playing with a temp box (i know, i probably not get the best sound for my personal taste, but i cant be bothered at the mo!)
thank you so much i am really appreciative for all the help!

[garfa]

also when i am using win isd and i select 2 drivers, does it assume that they will be seperated from each other or sharing the box. i would have said sharing.....
also whats the go with the phase shift and groud delay? what are they?

[StoneX]

I don't have WinISD or BassBox Pro installed at the moment so I can't tell you what size I think would work.

Basically, group delay is certain frequecnies of audio being delayed by a a certain amount of time. The more delay the "laggier" the audio will sound. The was a number that I was told to try to keep the group delay under, but I forget it... It think it was under 8ms or something.

Group Delay
I'm not sure how a small amount of phase shift effects the sound. But 180 degree phase shift is like wiring the + and - backwards, as far as I know.

[phree]

Heres some curves for the two subs in a few different boxes.

If you enter 2 drivers it assumes a shared box, yes.

Group delay creates the time delay effect that is sometimes noticable from subs compared to the mids.Because the mids have a different group delay. i.e. you hear the strike of the kick drum from the mids and then the deeper thud from the sub...sort of. The transition has a noticable delay or lag as Stonex said. If you keep it below 20ms it is usually acceptable. You will notice that in the curve below the group delay is below 10ms down to 40Hz and only 13ms at 30Hz, as there is not much music below this frequency it would be fine. Excellent in fact IMHO.

Phase shift is the difference between electrical input and acoustic output. This is why sometimes when you reverse the phase on a sub it sounds better, it can cause cancellation at some frequencies sometimes. I don't worry about it when designing boxes.

These descriptions probably aren't very technically accurate because i'm not a speaker engineer. If you google them you will find heaps of info.

Cheers

EDIT: Yeah the link StoneX posted is excellent.

[garfa]

phree do you think you could show me a couple of screens of the ts and other perameters you entered into win isd pro? i tried the quoted ones and it said that some were incorrect.

[phree]

Yeah it can be like that. In the top box delete one of either QTS, QMS or QES. Then click on any other value in the table. It will then calculate the missing parameter. Once it does this, it will be happy, and let you sve it. You can change it back later if you wish. I found most times it calculates very similar figures to those it complained about. It is just a bit fussy.

It would be really nice to have xmax and Le.

[garfa]

does win isd (normal not pro) cosider the size of the driver in the box?
i have estimated the volume of the driver to be 20 litres each.
(eg: 12inch cone by 10inch height. 1508cubic in. then a 8in cone by 4in height. 268cubic in. so 1508-268 = 20litres)
this will be a rather large effect on the qtc of the box.
or should i just go with the 80litre box and bugger it?!

[StoneX]

The don't take up 20L each, some of the largest woofers available only take up 0.5cubic foot, which is 14L. A Pioneer TS-W306C is only 3.3L.

With WinISD, do you put displacement into the driver specs? If so, it allows for the displacement, if not, it doesn't.

You should really use WinISD Pro or BassBox Pro 6. BB Pro 6 can be found on certain P2P sites/programs if you look hard enough