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CleanSierra

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Posts posted by CleanSierra

  1. I wish I was able to test this out without it being super expensive. I just don't see how the calculator is correct. I entered in 2 12's and 40 mm xmax with 38 hz tuning and its telling me a minimum of 166.54 sq in of port. There's no way 2 12's need that much port.

    40 MM of Xmax is seriously hefty.

    And like N8 and myself said, you can surely get away with less in a vehicle cabin. Every vehicle is different and how much less depends on more factors than one.

    And it's not super expensive to test. Build two or three boxes, that's just a couple sheets of wood for a couple of 12s.

  2. But what determines TOO much port area? A TL, ears? I agree that less port area can be used since sound waves can't even fully generate in the vehicle cabin. Avoiding peaky response and mouse are the two biggest things.

    When you REALLY look at the purpose of the vented enclosure in general, the idea is not to BE flat responding if we want to get technical. Its to have a bump in output around tuning frequency and then to rollloff above and below tuning.

  3. There's your formula:

    http://www.carstereo.com/help/Articles.cfm?id=31

    You can get away with less in a vehicle cabin but I try not to cut from the suggested minimum number TOO much. The 15" per foot is a rule of thumb for MOST drivers. However, port area isn't driven by how much airspace you have. A given sub, just for generic example an 18" sub, will need the same amount of of port if it's in a 5 cube as it would if it's in a 6 cube box. Desired tuning, Xmax, and cone area is what should be being used to determine port area.

  4. Just making it clear, I was just makin a funny not trying to start a port area war haha

    I knew you weren't starting a war :) We are all good bro.

    I was just stating my approach to enclosure design in regards to port area. I think Xmax is an important factor in port area design. The part where it gets tricky is I'm not sure how accurate some of the company's Xmax figures are. Not DC specifically, but some I've seen that make me wonder.

  5. I've built several using the port area formula that I suggest and I have yet to make a peaky enclosure. I realize CJ has specific knowledge of real world experience with the subs in question. I've heard the Level 4s on a DC 3.5K I'm the same vehicle with two very different enclosures. They were in a forum member's vehicle with equipment that Cody sold him. The first enclosure had like 36" of port and got loud at tuning but fell on its face above and below tuning. The second enclosure has around 80-90" of port and it's way more musical and not nearly as peaky. The rolloff is much less noticeable and it's got more range for sure. The system sounds better with the larger port area. Granted, the first enclosure was UNDER what Cody suggests, so maybe it's not a fair comparison.

    I have yet to have port noise in an installation and I have yet to make box that doesn't have good musical range.

    I know Brian, Bkolfo, HATES the port area per foot recommendations because a sub needs X amount of port regardless of what airspace it's in. Xmax, tuning and cone area are supposed to drive the port area for a drive to operate efficiently, according to Small and all collected in the Loudspeaker Cookbook by Vance Dickason. I know there is a difference between theory and application though and I've built enclosures with less that the "mimimum" recommended. I've still tried to stay close since I believe in the formula.

  6. you like a lot of port krakin haha

    I recommend port just the same as Krakin. There are a few port calculators that really make it easy and they also offer the formula from Small as well. I use the same program that Krakin uses and it's also the one that Bkolfo uses. All from the Loudspeaker Cookbook. Two Level 4 12" subs are right at 85" using the same formula.

    And Krakin's suggestion was slightly under what the calculator suggests. It's actually 62.31"

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