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Port Velocity Equation


DLHgn

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You might be able to reverse engineer his formula if you download his spreadsheet as an Excel Spreadsheet, then review the formula he uses there. I was able to download and see the formula, but I have no idea where some of his numbers come from.

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I've been watching this thread and I've been meaning to reply, I just haven't had a chance until now.  

It should be possible to switch my formula around and get port velocity out of it.  All the math is posted in the thread I made for it here: 


I'll try figure out the math for ya, but I may not get to it for a while.  

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Interesting problem to solve as ALL T/S specs work together but the bottom line it seems to me is how power/excursion/volume/tuning all contribute to affect the port area. Keeping the velocities around a certain targeted level at whatever power you're getting after rise would be ideal.

IMO to find the area needed in a perfect world and on the 1st attempt would be knowing the amount of rise then using that input within whatever modeling program you're using.

Some folks swear by 12in2 per foot to get low... I personally try to estimate rise then find the area needed and keep the velocities high but within limits in the box size selected. Impedance rise is usually above estimated levels so whatever I come up with has velocities lower than estimated. Some are 12in2^ft3 some above 16in2^ft3... just depends on power/excursion in whatever sized/tuned box I'm currently doin'... can't see how a simple formula can cover all the ground needed to come up with an accurate result everytime... but I'm tuned in for sure and wish you luck with the outcome.

back to lurking.... sorry

 

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16 hours ago, shredder2 said:

Interesting problem to solve as ALL T/S specs work together but the bottom line it seems to me is how power/excursion/volume/tuning all contribute to affect the port area. Keeping the velocities around a certain targeted level at whatever power you're getting after rise would be ideal.

IMO to find the area needed in a perfect world and on the 1st attempt would be knowing the amount of rise then using that input within whatever modeling program you're using.

Some folks swear by 12in2 per foot to get low... I personally try to estimate rise then find the area needed and keep the velocities high but within limits in the box size selected. Impedance rise is usually above estimated levels so whatever I come up with has velocities lower than estimated. Some are 12in2^ft3 some above 16in2^ft3... just depends on power/excursion in whatever sized/tuned box I'm currently doin'... can't see how a simple formula can cover all the ground needed to come up with an accurate result everytime... but I'm tuned in for sure and wish you luck with the outcome.

back to lurking.... sorry

 

f7D1ME.jpg

Really, the only thing needed to calculate port area is Power, net box volume, port area and tuning. 

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