SPL Comp

[sweefu]

Well, WOW sight and sound are holding a sound comp, and me and some mates figure we should have a crack at it. Our devision is

3x8" or 2x10" or 1x12" sub
Up to 750wrms amp
Thats it!

So we were thinking of using:
Alpine type X 12"
Infinity reference 610a .. 660wrms @ 2ohm
Huge Huge Huge ported box, tuned low
Subaru Fiori
Possibly spare truck battery we have, the fiori's stock battery is very small.

What i need help with, is the box design. At the moment i haven't measured the boot of the car so i dont know the dimensions, but looking for a cu.ft value and help with the port tuning. This box will only be used for this competition, won't ever be used for listening to normal music.
Also, i have a tonne of 90mm storm water pipe, would be great if i could use that for the ports.

Comp is on the 29th of this month.

Any help would be great,
Cheers!

[holdenboy]

Too easy, except you wanna tune high (50+hz) to get maximum SPL. I wouldnt go heaps big on box volume, it'll end up hurting your score. But definitely bigger than a normal ported box.

Ideally, you also want to get some "meter time" before the comp so you can test / tune the system.

I'd say a box around 2.5-3 cu.ft. With 2 or 3 90mm ports, sub up / ports back (like my old box). Make it out of 18mm MDF and you'll be right, if you want you just PM me and we can sort it out there?

[sxc_sound]

ports should be firing same direction as subs? otherwise it will be epic out of phaze.

Definitely have the sub firing up though!! my mate runs constant 145.1db with 1 x orion 15" sub in a honda civic

[holdenboy]

Its not always the best way to go, certainly is the "tried and true" method but this style is better for hatchbacks / wagons etc. It wont be out of phase by much, the port loads off the hatch / tailgate and the subs off the roof.....do a search on "CRX box" and you'll see its popular among the Db Draggers.

I think i gained 2.5db by going subs up port back as opposed to subs / port back.

[calais_cruzin]

X types dont really like ported boxes aye, reccommened port tune is 45hz

90mm ports wont be big enough, id go 150mm. or even bigger

My 90mm was soo chuffed out

[holdenboy]

Yeah, ive been discussing it with him over PM, but it seems thats the best choice for a 12" sub he's got. That port tune (45hz) is almost ideal for SPL, a little higher would be better though.....i'd say the car will peak in the mid 50s, 58 maybe.

90mm is too small, but 150mm is also dear! Thats why i said 2-3 of them

[2LOUD2OLD]

i wanna know more about this comp, where can i find the info?
sorry for off topic

[sweefu]

No worries dude, best thing is to swing by wow in fyshwick and pick up an entry form from the car audio section.
There are different divisions that allow different amount of rms watts, subs etc, as well as a pro open class.

[2LOUD2OLD]

thanks, not so much interested in competing, more interested in sussing out how its run...... unless there is SQ but i doubt it
I am on the organising commitee for MEAACT and it is always good to see how others run their comps

[sweefu]

Yeah no SQ mate i was disappointed too. Its on the 29th of this month, from 12pm to 4pm. If you come mate let me know, really keen to see your car.

Actually, there are also awards/trophies/gift vouchers for cars that "go hard" and "show stopping install" and things like that.

[2LOUD2OLD]

looks like i will be coming along for a sticky beak. won't be competing, but will be there to hand out flyers to our comp next weekend :P

[2LOUD2OLD]

hmm actually maybe not, too wet

[sweefu]

haha i didnt go either. My mate with the sub bailed out so i had no sub to compete with

[holdenboy]

Aww man......i wanted to know how you went