help with aeroports

[juanl 0]

i have a question i have an 1.25 cubic inch pvc tube for 1 15" and i want to tune it to the peak freq. of my car. i dont know what frequency is best for spl in my car i have a 4 door mitsubishi mirage and im going to use aeroport 3" and the woofers are RE XXX thanks in advance im new to this of port is there any advantage using larger aeroports

in sealed i measured in the 58 thanks

[///M5 2,833]

Huh?

1.25 cubic inch what?

3" aero is too small for a 15" XXX

what are you asking?

[juanl 0]

ok im using pvc tubes for the woofer and i want to do something like this

i dont know what tuning freq is better for my car for spl because i always use sealed pvc if you think 3" aero are too small what you think is better for me thanks.

[danracer 0]

he has 2 15" pvc pipes that the internal volume is about 1.1-1.2 cu in. and he wants to port them strictly for spl applications...what would be the best size for the aeros..

[KU40 173]

you mean 1.25 cubic FEET? that's still way too small for those subs. Why don't you just build a regular box that's more accurately sized, like 4+ cubic feet? 1.25 is going to choke those subs and you're not going to get the max SPL you're after. As for aeroports, I'd say at least 2 4" aeroports or 6" even better.

[juanl 0]

well in my car to do a bosed of 4 cubic feet its a little imposible because they are 2 and in puerto rico theres a category using tubes and i dont want to change thyat category thanks man at what frequency is better to tune mny car thanks

[Lord Baccus 1]

what freq are you trying to tune to ?

ill use BBp6 to figure it out ?

[danracer 0]

he used to measure at 58hz so im guessing thats the peak freq of the car so probably he should tune to about 52-53hz

Edited April 29, 2008 by danracer

[MKader17 332]

Why don't you use some bigger tubes and mount a smaller driver in them. If the driver meets its airspace requirements it will get a lot louder.

Could you buy 90* bends so you could fit more airspace and still be considered tube?

Also Punctuation is your friend....

[danracer 0]

perhaps he could do a 22 inch pipe giving him an aproximate of 2 cuft of internal volume...

[juanl 0]

if i use larger tubes like 20" or something like that gives me like 2 cubic feet i can use smaller aeroport or not

i measured the car and did 151.6 outlaw with less than 1 cubic feet sealed in tube

Edited April 29, 2008 by juanl

[Lord Baccus 1]

according to BBP6

in a cylinder 1.2cf

and using areoports 3" round

they will need to be 4.125" lonl including both flared ends

so ports are 3"x4.125" = 52/53 Hz

did not account for displacement of sub as i did not have it to add to the specs

[KU40 173]

weird, I've never heard of a tube class.

[Lord Baccus 1]

weird, I've never heard of a tube class.

Bazooka

http://www.sasbazooka.com/

[danracer 0]

its at a local organization...we dont have dbdra or iasca here...

[KU40 173]

weird, I've never heard of a tube class.

Bazooka

http://www.sasbazooka.com/

yeah I know of Bazooka and all their "awesomeness." I was just meaning a tube class in an SPL competition.

[juanl 0]

as dan said is local competition we dont have iasca or dbdrag and they divide us like that

[///M5 2,833]

1.25 cuft and a 15" XXX ported will not get loud. You need more airspace. As for port area try for more than 15" per cubic foot, but you NEED WAY more space.

[danracer 0]

whats the recomended airspace of the XXX i cant seem to find them

[juanl 0]

ok and if i use a 2.0 cubic feet tube with 6" aeroport could this work or still not im trying to get it the most compact posible because i dont want the woofer inside my car jejejejeje

[///M5 2,833]

I really doubt it. I don't have the recommended box for a 15" xxx in front of me, but I'd guarantee it needs a lot more airspace than that. If htat is all the space you have you should get a different driver.

[KU40 173]

I'm sure the 15" XXX would like 4+ cubic feet in a normal situation.

However, will it work and make sound in a tube as small as 1.25 cubic feet? yes. I mean you say you hit over 150 with that, so it must not be terrible, right (albeit sealed)?

The problem is that with smaller airspace, the peak frequency of the sub/box combo increases. That is to say, if you had a 4 cubic foot box tuned to 40 hz and a 1 cubic foot box tuned to 40 hz, the 4 cube box would have a peak in output at probably 45-50 hz. the 1 cube box would have it's peak way up at maybe 70 hz. This would be bad if you want to play a tone around 50 with your car. You might want to download winISD and plug it in there to see how it looks and what i mean. I'm at work or else I'd do it. This isn't to mention the efficiency increase you'd see with a larger box as well.

But as someone else mentioned, you might get better results using a smaller driver that is more suited to that size of tube. maybe a 10" XXX. It's hard to say whether the more ideal box for the 10" would outperform the too small box for the 15" due to increased cone area that the 15 has.

Edited April 30, 2008 by KU40

[Lord Baccus 1]

i was playing with a 3cf boxx for my 15" and went into BBP6 and dropped the cf to 2.0cf and my responce curve took a dive so i played a lil more and got to 2.75cf befor seeing a positive responce from the curve,

now that is with all of the subs T/s & displacement input into the BBP6 software,

when i did yours i had NO info on the T/S of the sub your using.

[juanl 0]

I'm sure the 15" XXX would like 4+ cubic feet in a normal situation.

However, will it work and make sound in a tube as small as 1.25 cubic feet? yes. I mean you say you hit over 150 with that, so it must not be terrible, right (albeit sealed)?

The problem is that with smaller airspace, the peak frequency of the sub/box combo increases. That is to say, if you had a 4 cubic foot box tuned to 40 hz and a 1 cubic foot box tuned to 40 hz, the 4 cube box would have a peak in output at probably 45-50 hz. the 1 cube box would have it's peak way up at maybe 70 hz. This would be bad if you want to play a tone around 50 with your car. You might want to download winISD and plug it in there to see how it looks and what i mean. I'm at work or else I'd do it. This isn't to mention the efficiency increase you'd see with a larger box as well.

But as someone else mentioned, you might get better results using a smaller driver that is more suited to that size of tube. maybe a 10" XXX. It's hard to say whether the more ideal box for the 10" would outperform the too small box for the 15" due to increased cone area that the 15 has.

ok and if i use 2.0 cubic feet i downloaded winisd in my other computer and i didnt know how to use it i was making some testing and yes with sealed tube with less than 1 cubic feet hit over 150 if i cant figure this out im thinking using it sealed but with 1.5 cubic feet thanks

[///M5 2,833]

Sealed is a way different story from ported.