Car Ported Subwoofer: Can the port be Outside the box? - diyAudio
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Old 21st May 2002, 10:08 AM   #1
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Question Car Ported Subwoofer: Can the port be Outside the box?

http://www.subzoneusa.com/snake_tube.htm

Check out that link...

It says that I can put the port Outside the box and into the cabin of my car? Is that true? Can the port be on the outside rather than on the inside? My sub requires two 4"x15.5" and my box's depth will definitely not be 15", that's just too long for my trunk, I still want my trunk to be useable heh. I don't want the port to be on the side, mostly because of looks and it will be too close to the sides of my trunk.

So is there any negative things about having a curved port rather than a straight one? And can I really put the ports on the outside and drill a hole beside my 6x9's and into the cabin???

Thanks,
mark



http://www.subzoneusa.com/snake_tube.htm
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Old 21st May 2002, 06:56 PM   #2
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Go to home depot and get some PVC and some elbows for it. You could use an exhaust hose for a dryer if you want something flexible. That aught to keep your ears popping. Course if you blow your ears in real hard it will pop your eyes out of your head!
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Old 21st May 2002, 07:03 PM   #3
subwo1 is offline subwo1  United States
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Though, I would use only solid tubing for the port. You could join bends with elbows.
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Old 21st May 2002, 07:22 PM   #4
Bill F. is offline Bill F.  United States
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>Can the port be on the outside rather than on the inside?

Yup. No problem. Putting it inside just keeps it out of the way.
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Old 21st May 2002, 07:59 PM   #5
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Cool thanks guys for the help. I plan to just go to Home Depot and make it out of solid PVC piping and run it up to the cars cabin. I'm guessing the PVC would result in less noise than a flexible port.

Thanks again,
mark
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Old 21st May 2002, 08:20 PM   #6
Bill F. is offline Bill F.  United States
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>I plan to just go to Home Depot and make it out of solid PVC piping and run it up to the cars cabin.

Help me picture this. Are you saying you're going to have both the driver and the port firing into the cabin (vented), or just the port (bandpass)?

Bill
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Old 21st May 2002, 09:41 PM   #7
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The box I am going to build will just be vented (bass reflex), not bandpass.
My sub requires two 4" x 15.5" and that will run from the top of my box to the cars cabin. The sub will be facing the rear of my car and the ports will be on top of my box leading to the cabin.

l PP
l PP
l l--------l
l O l
l l--------l
----------------------

O = Subwoofer
P = Ports

It's a wierd picture, but I hope you understand.
This is inside my cars trunk.
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Old 21st May 2002, 09:54 PM   #8
Bill F. is offline Bill F.  United States
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The reason I asked is because it sounded to me like you were planning to place a vented sub box in your trunk (driver firing into the trunk space) with only the reflex ports actually firing into your cabin. Is this correct?

If so, this sounds like a recipe for one-note bass. With this arrangement, the only clear bass you'll have is the resonance of the port. Everything else just goes into your trunk.

If you only wish to bring ports into your cabin, you should go with a bandpass alignment where all the bass comes through the ports, not just one note.

Look here for a side-by-side comparo of alignment types http://snippets.org/ldsg/boxes.php3#ISOBARIC

Bill
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Old 21st May 2002, 11:52 PM   #9
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Aren't all in auto subs basically one note because of the size of the car? Most of it is felt and not heard since there isn't enough space. Maybe if all the windows are open. 2 15" drivers that are made to get down to 20 Hz or so? The whole inside of the car might not be large enough unless it acts as an acoustic suspension. A ported box for one of my Altec 421s for 30Hz is 10 cu ft plus the volume of the driver and ports to get it back out to 10 cu ft. I'm sorry, I just can't see what difference it makes where the air gets compressed the most. Once it goes below what the volume of the inside of the car can handle does it really matter? Real question. This has been bugging me. I have a little extended cab truck and my down to 80Hz speakers seem to sound better in the bass if a window is open. I like bass. I can't adjust it on my main amp in the house but there is plenty of it there. Dry wax will make my ears buzz and the specs on my speaks say 28Hz which means they won't go down to 30 except in a lab. I'd bet on the back loaded 15" folded going down to 30 but that is the center channel for movies.
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Old 22nd May 2002, 05:19 AM   #10
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Thatch, according to Vance Dickason, speakers generally can get 20 dB GAIN at 20Hz in a closed field environment (car). The one note bass phenomenon however, is true, whether you have the port firing into the cabin or not. Bass notes travel just fine through car seats. Band pass alignments in cars are Strongly discouraged. The response gets all fudged in the closed field. Same with vented boxes. Response is anything but flat. The flattest you can get in a car would be a well damped sub in a smaller than normal sealed box crossed over at Fc.
I made a science project out of this.
andy
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