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Discussion Starter #1
Hey I was wondering if anyone could help me build a ported box for my 12in kicker L7. I was looking at this... http://www.ehow.com/how_5076996_build-ported-box-kicker-l.html ...and it looks pretty straight forward. Then I measured the trunk and saw I have an area to work with of about 27"wide x 24"deep x ~13.5" high... So what I don't get is how to calculate the interior volume because the formulas when I searched on google were complicated as hell and make no sense to me (remember it's ported).

it should be 3.25ft^3 interior volume with a port that's 3" x 13.25" and a length of 14.5"
 

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L7 in a ported box will be loud and have inferior sound quality compared to a better SQ sub in a sealed box. Do you prefer loud over SQ? To each their own.
 

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L7 in a ported box will be loud and have inferior sound quality compared to a better SQ sub in a sealed box. Do you prefer loud over SQ? To each their own.
False.

A properly tuned ported enclosure will produce alot better low end sound than a sealed enclosure. It's simply a more efficient design.

Don't believe me? Walk into your local high end home theater dealer. Look at the subwoofer setups costing $3000+ You will not find a sealed enclosure among them.
 

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Discussion Starter #7
Thanks, that site is really easy.
The only thing is when I set everything up to those recommendations above, the tuning frequency isn't 40 like it said, it's like 26.8. Is it because its FB not Hz?
 

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False.

A properly tuned ported enclosure will produce alot better low end sound than a sealed enclosure. It's simply a more efficient design.

Don't believe me? Walk into your local high end home theater dealer. Look at the subwoofer setups costing $3000+ You will not find a sealed enclosure among them.
Response can not be as quick in a ported box as sealed. Simple Physics.

Low end sound. You are specifying a range of frequency. Of course ported boxes are more efficient in their tuned frequency! I didn't say they weren't, i said it would be loud. Ported box drops off dramatically above the tuned frequency. A sealed box will maintain the same loudness (aprrox depending on box ) for a wide range of low frequencies. IF you want loud go ported, louder get a 6th order bandpass. Your speaker response is will suffer. You can't argue that, unless you don't understand physics.

You are also talking about home theater, which is designed completely different than a car subwoofer, so its a worthless point.

The OP is talking about an L7 kicker, which is a dirty sub. There are clearly much better SQ subs to chose from.
 

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Response can not be as quick in a ported box as sealed. Simple Physics.

Low end sound. You are specifying a range of frequency. Of course ported boxes are more efficient in their tuned frequency! I didn't say they weren't, i said it would be loud. Ported box drops off dramatically above the tuned frequency.

I'm just going to assume you mean below the tuning frequency. Which would be correct. Above the tuning frequency you can achieve a almost perfectly flat frequency response graph with a ported enclosure until you start to approach F3

A sealed box will maintain the same loudness (aprrox depending on box ) for a wide range of low frequencies. IF you want loud go ported, louder get a 6th order bandpass. Your speaker response is will suffer. You can't argue that, unless you don't understand physics.
Above the tuning frequency you won't lose any speaker response ported vs sealed. Granted porter may have a hair slower response, but it won't be noticible. Below the tuning frequency the cone of the woofer unloads and yes, you do lose response.... along with a woofer.

You won't see as dramatic of a rolloff with a sealed enclosure, but you can't tell me that you cannot use the boost around the tuning frequency of an enclosure to produce a better low end response. Stating that a sealed box will maintain the same loudness just means you don't tune your ported enclosures properly. I've got a ported box sitting in my garage that doesn't vary more than +/- 1dB playing a 35Hz-200Hz frequency sweep.

Use the tuning frequency boost to extend the F3 point to a lower frequency, not to simply make sounds around 50Hz ridiculously loud. SPL guys use that boost to get dumb loud at higher frequencies, obviously not always the goal. 6th order bandpass enclosures basically create "one note wonder" boxes. Flat frequency response is the goal in SQ vehicles. As for your home theater comment, the only diffrence between car audio and home audio boils down to cabin gain... Which you do have to a degree in a home audio enviroment... if you're putting subs in a tiny bathroom. Usually room size negates that in a home environment.

Have you ever tried to build a 6th order bandpass enclosure btw? Feel like making your head spin? Try it. You have to build those things PERFECTLY.

You are also talking about home theater, which is designed completely different than a car subwoofer, so its a worthless point.

The OP is talking about an L7 kicker, which is a dirty sub. There are clearly much better SQ subs to chose from.
Doesn't mean the proper enclosure can't help it sound better.
 

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Discussion Starter #10
can anyone help me out with tuning frequency because I don't think I can build a box with 40hz with the trunk space I have available, or atleast I can't figure it out with this program.
 

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can anyone help me out with tuning frequency because I don't think I can build a box with 40hz with the trunk space I have available, or atleast I can't figure it out with this program.
Larger port = lower frequency...

conversely...
 

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some one correct me if im wrong but i think you should get the frequency a tad bit lower then 40 mabey 37 ish
 

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Discussion Starter #14
if the port is too big does that affect sound quality?
and do i have to have the L shape design for the port? or can it be just one board without the second one at a 90 degree angle?
 

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if the port is too big does that affect sound quality?
and do i have to have the L shape design for the port? or can it be just one board without the second one at a 90 degree angle?
There are many diffrent styles of port... Alot of people use winISD to design thier boxes and use a simple round port. (Hint: 4" PVC makes an excellent port tube) The L port has some advantages, as far as enclosure size goes, because it uses a wall of the enclosure as a port. The downside being you can experience port noise if you don't "round off" the 90* bend a bit. Same can be said for round port tubes without flared ends.

You don't have to keep the L shape with that calculator either... just enter 0 as the length of the "bend" Round the edges of that board though. A roundover bit on a router would be ideal, but I'm sure you could just sand it with a dremel or likewise.
 

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Discussion Starter #16
okay, adjusted to this, what do you think?

width: 26
height: 14
depth: 22
wood thickness: .75
port height: 12.5
port width: 3.5
port length 1: 19.75
port length 2: 0
Box Volume: 3.024
frequencey: 36.52
 

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I had an L5 with a 3 cubic foot aero-ported box tuned to 30 hz frequency it sounded amazing on those real low hitting songs. It basically all depends on the kind of music you listen to some boxes handles lower bass better, other boxes handle higher bass. It all depends on what your looking for and people that say the SQ on the L7 is not good know nothing about what they are saying. L7's have great SQ but their SPL does outway their SQ and SQ can vary from person to person not everyone is the same.
 

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Discussion Starter #18
There are many diffrent styles of port... Alot of people use winISD to design thier boxes and use a simple round port. (Hint: 4" PVC makes an excellent port tube) The L port has some advantages, as far as enclosure size goes, because it uses a wall of the enclosure as a port. The downside being you can experience port noise if you don't "round off" the 90* bend a bit. Same can be said for round port tubes without flared ends.

You don't have to keep the L shape with that calculator either... just enter 0 as the length of the "bend" Round the edges of that board though. A roundover bit on a router would be ideal, but I'm sure you could just sand it with a dremel or likewise.
sorry in advanced for the sorry attempt at drawing the box
I'm confused though, which parts are you talking about rounding out?
blue, red, green?
 

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Blue mostly.

Although a little wood filler putty and some sanding wouldn't hurt on the red edge too. When air tries to bend around those sharp corners (flowing in and out of the enclosure) it tends to "snap" and produce port noise... Hence the rounding.
 
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