DylanOhara Posted March 29, 2020 Report Share Posted March 29, 2020 New to the forums. Been lurking for a little while. Very new to big bass and quality bass. I currently have 2 JL Audio 8s and 2 Kicker Comp RTs that will be coming out. I'll be running a DD Audio M3C with a Sundown Audio X18 v.2. I bought second hand and saw this setup run in the previous owners vehicle, but I want to design a box optimized for my 2014 Crewmax Tundra that doesnt cause me to lose the entire rear seating area and still allows me to see out the rear window. I read Hugh G. Rection's post on slot port vs. round port and this has me decided on slot port(s). Sundown Audio recommends 112in^2 of port area. I can achieve this +/- 2" with either one 12" round port or four 6" round ports. I'm struggling to find information on wether or not port length is critical. From what I gathered on Hugh G. Rection's post the longer the port the less efficient it will be due to surface contact area of the escaping air, but I know there's gotta be some optimal length calculation. Link to comment Share on other sites More sharing options...
will77530 Posted March 29, 2020 Report Share Posted March 29, 2020 Length is how you get your tuning Link to comment Share on other sites More sharing options...
DylanOhara Posted March 29, 2020 Author Report Share Posted March 29, 2020 1 hour ago, will77530 said: Length is how you get your tuning Is it relative to surface area? Any articles or suggestions for understanding the science of it? Link to comment Share on other sites More sharing options...
fishchris1 Posted March 29, 2020 Report Share Posted March 29, 2020 The port length to SQ inch ratio is super important. The shape of the port, not so much. A round port is the most efficient, but as long as you have enough SQ inches of port for your subs (adding maybe 15 or 20% for a square vent) you will be fine. You can get this info from the sub manufacturer. Ported rectangle boxes are super easy to build, and there are many free programs that will tell you your port length / SQ onches for a given tuning also. One more thing... Do you want musical ? Or LOUD ? A lower tuning of say 28-35 will typically play deeper, and sound better for music. A higher tuning of like 40-45 will sound very loud, and rattle your brains, but is a lot peakier, and not so musical. It's up to you with what you want to achieve. Link to comment Share on other sites More sharing options...
DylanOhara Posted March 30, 2020 Author Report Share Posted March 30, 2020 20 hours ago, fishchris1 said: The port length to SQ inch ratio is super important. The shape of the port, not so much. A round port is the most efficient, but as long as you have enough SQ inches of port for your subs (adding maybe 15 or 20% for a square vent) you will be fine. You can get this info from the sub manufacturer. Ported rectangle boxes are super easy to build, and there are many free programs that will tell you your port length / SQ onches for a given tuning also. One more thing... Do you want musical ? Or LOUD ? A lower tuning of say 28-35 will typically play deeper, and sound better for music. A higher tuning of like 40-45 will sound very loud, and rattle your brains, but is a lot peakier, and not so musical. It's up to you with what you want to achieve. I want musical. I listen to mostly metal but occasionally some rap like Hopsin, Tech9, or Logic. Manufacturer suggests 32hz. I'll try to find a program to lay it all out. Link to comment Share on other sites More sharing options...
DylanOhara Posted April 1, 2020 Author Report Share Posted April 1, 2020 So I'm trying to use speakerboxlite and it keeps auto filling dimensions for me. I'm struggling with the box design portion of my build to be honest. I want it right the first time. I know the volume necessary for my box build, and I know my port area necessary, I just can't find anything solid on calculating port length for specific frequency. I know I need an internal volume of 7ft^3 after all displacements(subwoofer, braces and stiffeners, and ports) I know I need a port area of about 112in^2 which i can get +/-2" with four 6" round ports. I can figure both of those out once I have the final piece of the puzzle and that's port length. I'm just struggling to figure out how long these ports need to be to get around 32Hz. Someone hit me with some knowledge or even with some formulas or reading material. Link to comment Share on other sites More sharing options...
CrackFactory Posted April 1, 2020 Report Share Posted April 1, 2020 Use this for calculating port length. http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CAL Port lenth 1.htm Here's what I got. https://i.imgur.com/kYPTb49.png Link to comment Share on other sites More sharing options...
DylanOhara Posted April 1, 2020 Author Report Share Posted April 1, 2020 30 minutes ago, DylanOhara said: So I'm trying to use speakerboxlite and it keeps auto filling dimensions for me. I'm struggling with the box design portion of my build to be honest. I want it right the first time. I know the volume necessary for my box build, and I know my port area necessary, I just can't find anything solid on calculating port length for specific frequency. I know I need an internal volume of 7ft^3 after all displacements(subwoofer, braces and stiffeners, and ports) I know I need a port area of about 112in^2 which i can get +/-2" with four 6" round ports. I can figure both of those out once I have the final piece of the puzzle and that's port length. I'm just struggling to figure out how long these ports need to be to get around 32Hz. Someone hit me with some knowledge or even with some formulas or reading material. So I found a few calculators, but when given the following values: port diameter: 5.915" number of ports: 4 tuning frequency: 32Hz enclosure volume: 7ft^3 I get a port length of close to 37". Is this 37" of total port as in 9.25" each, or is this four 37" long ports? Link to comment Share on other sites More sharing options...
DylanOhara Posted April 1, 2020 Author Report Share Posted April 1, 2020 9 minutes ago, CrackFactory said: Use this for calculating port length. http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CAL Port lenth 1.htm Here's what I got. https://i.imgur.com/kYPTb49.png Thank you for your help brother. This is what I found also, but does this mean a total length of 37"(9.25" each), or four ports 37" long. Link to comment Share on other sites More sharing options...
DylanOhara Posted April 2, 2020 Author Report Share Posted April 2, 2020 On 4/1/2020 at 1:54 AM, DylanOhara said: So I found a few calculators, but when given the following values: port diameter: 5.915" number of ports: 4 tuning frequency: 32Hz enclosure volume: 7ft^3 I get a port length of close to 37". Is this 37" of total port as in 9.25" each, or is this four 37" long ports? Any input on this? Link to comment Share on other sites More sharing options...
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