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Center Slot Port help!


vnisme

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I've read that before and is the calculation I use with modification to the end correction. So, I have decided to use the correct end correction for his application and compare it to what you were saying about half and what not.

What RE calculator said: 33.52 Hz

With 3 common wall JL's stock equation: 39.9Hz

With 3 common wall equation with updated end correction: 32.45 Hz

With 2 common wall added 1/2 of port width to stock equation: 37.54 Hz

With 2 common wall added 1/2 of port width to equation with updated end correction: 33.02 Hz

With 2 common wall just equation with updated end correction: 34.6 Hz

This is assuming 11892.5 in^3 net volume, 124 in^2 of port area, 21.25 inch port length (without the 1/2 added)

Did you see the port length of 34" and how do you think re calc came to the total port length?

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I did not see that but I plugged that into the calculator. With JL's stock end correction (.823) I got the same tunning of 33.52 Hz but with the updated end correction (2.227) I got 28.72 Hz. With another equation (from http://www.diysubwoofers.org/misc/portcal.htm) I get 27.96 Hz using a 3 common wall end correction of 2.227. The two equations differ from each other but get close enough to give you a good idea of what to do.

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Thanks for the calculations guys! I appreciate it! So even if the slot is on the side, the subwoofers are likely not going to behave so differently where it matters correct? I just want to know my options, I know it is a tight fit. MIght think about going down to 2 12's instead.

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If he wants a center port it is more work to have a double chambers as the ports would need to be "L" slots!

What do you mean by double chambers?

There is some more info this is thread, http://www.stevemeadedesigns.com/board/topic/163147-box-design-for-2-p3s/

Once the port reaches the back wall you change it to two 4" ports one for each separate chamber.

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I did not see that but I plugged that into the calculator. With JL's stock end correction (.823) I got the same tunning of 33.52 Hz but with the updated end correction (2.227) I got 28.72 Hz. With another equation (from http://www.diysubwoofers.org/misc/portcal.htm) I get 27.96 Hz using a 3 common wall end correction of 2.227. The two equations differ from each other but get close enough to give you a good idea of what to do.

That looks better to me now. Could you do some math and tell me how close I came to getting my port right? http://www.stevemeadedesigns.com/board/topic/206458-4th-order-for-single-jl-10w6v3/

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If he wants a center port it is more work to have a double chambers as the ports would need to be "L" slots!

What do you mean by double chambers?

There is some more info this is thread, http://www.stevemeadedesigns.com/board/topic/163147-box-design-for-2-p3s/

Once the port reaches the back wall you change it to two 4" ports one for each separate chamber.

Oh ok, yeah they're not separate in the sense of totally isolated. Yeah, whenever you have a port split to either side like that you use half of the width for the two sides. A problem with that is that it takes a lot of internal volume.

I did not see that but I plugged that into the calculator. With JL's stock end correction (.823) I got the same tunning of 33.52 Hz but with the updated end correction (2.227) I got 28.72 Hz. With another equation (from http://www.diysubwoofers.org/misc/portcal.htm) I get 27.96 Hz using a 3 common wall end correction of 2.227. The two equations differ from each other but get close enough to give you a good idea of what to do.

That looks better to me now. Could you do some math and tell me how close I came to getting my port right? http://www.stevemeadedesigns.com/board/topic/206458-4th-order-for-single-jl-10w6v3/

I couldn't really help you with that. If we're being quite honest, I have no experience with 4th orders. Would help you if I could.

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