ive run out of room can i put the port outside the car? - diyAudio
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Old 25th February 2010, 02:25 PM   #1
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Default ive run out of room can i put the port outside the car?

i am still trying to understand how a port on a speaker box works but i now realize that it doesnt make any difference if the port is inside or outside of the box just as long as the port starts close to the speaker. true? not true?

i am wondering if i can route the port out the back of the speaker box to the outside of the car then come back inside? this might sound like a goofy idea but i think this would actually save me a lot of space and the vehicle i am working on it wouldnt like completely ridiculous at all.

i know how crazy this sounds but i am quite serious about doing it. i have enclosed an artists rendering hehehe
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Old 25th February 2010, 02:34 PM   #2
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How long is this port? Your 'artists rendering' =D makes it look like it's about 8 feet long. Try altering the port dimensions in order to get it shorter, unless you're trying to fit the sub to a smart car there should be plenty of room for a port.

As far as I'm aware it doesn't matter if the port sticks out or in, it forms a resonant system with the box, just most of us don't want our sspeakers looking like elephants. The problem is the port does act like a delay line, it'll take time for the pressure wave to go from the back of your speaker all the way round your car in the tube lol.

In short keep the port short and you should have no troubles
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Old 25th February 2010, 03:27 PM   #3
godfrey is offline godfrey  South Africa
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Funniest pic I've seen all day! How about using that for your avatar?

Seriously though, putting the port outside the box is no problem but that pipe looks much too long for reflex loading.

Even if the box tuning looks right by a simple calculation, if the pipe's longer than about a foot, you'll have nasty pipe resonances starting right down in the bass.

You could do a transmission line or horn design like that though.

Oh no - now I've got a picture in my head of what a bass horn would look like stuck on top of the cab, firing in through the roof!
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Old 25th February 2010, 03:39 PM   #4
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As long as you remember that the area of the port must go up with length, you'll notice that the area will have to be huge.

The idea of a port is to link the inside of the box with the rest of the world. It can stick out of the box, but that's rarely a good idea, as it's more likely to get bashed etc.
Generally speaking, they protrude into the box. While taking up a little box volume, it's better than having a huge extension to the box that you must keep air tight (ie, no leaks in the port.

Question - why do you want the port next to your head? There's no need for it to be there, unless you're after some kind of subsonic hairdryer... (wait, that sounds cool - I want ot try that.)

Chris
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Old 25th February 2010, 03:40 PM   #5
jbell is offline jbell  United States
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yea, agree... the "mr. bill" pic caught me funny too.

Bandpass boxes in standard cab minitrucks beds, with the ports firing into the cab was quite popular at the local army base... The key was a flex rubber duct from the bed to the cab, to deal with frame flex. Never did a horn that way though... hmmm....
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Old 25th February 2010, 07:46 PM   #6
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That's why you get an extended cab!
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Old 25th February 2010, 07:48 PM   #7
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Yeah you can put the port outside - but it won't augment the inside LF at all... AND you had best have a wadfull of $$ to pay off those tickets!! Wheeeee!

_-_-bear

EDIT: oh wait a sec, you want to run the port outside the car and back IN? sure... but then it is mostly a TL (transmission line). Cool, do it in chrome, baffle the passersby...
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Old 25th February 2010, 08:48 PM   #8
Flaesh is online now Flaesh  Russian Federation
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i forgot brend..there was normal BR sub and additional external port in form long enough bent tube(for additional money) for "more deep bass"
good mareketing, imo
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Last edited by Flaesh; 25th February 2010 at 08:51 PM.
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Old 25th February 2010, 09:00 PM   #9
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Long port options for subwoofers
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Old 25th February 2010, 10:21 PM   #10
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the port doesnt need to be that long i just put it in the picture to show that i wouldnt have any restriction on length. i had another DIY guy help design me a box and i am building it to his specs.

"6.2 ft^3 tuned around 27-28 Hz with an 8" diameter vent 23-24" long"

thats a huge port. and i figure any space help i can get will leave me space to possibly run a 3rd or 4th sub woofer. ideally i would like to make a box that is as narrow as possible and just really tall

the first picture was just an idea i had but i can also build a shorter port like this new and improved artists rendering. the port doesnt have to be directly over my head it can be placed in the center of the truck or wherever thats what is so great about this idea. as long as i am allowed to leave the truck with the port and come back in again i think im golden!!

whats a transmission line?

bp im all for your idea of building a horn like that but try and fit 4 of them in your truck, so far the this is the best idea i have come up with.
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Last edited by scampo77; 25th February 2010 at 10:30 PM.
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