dylan117 Posted November 3, 2015 Report Share Posted November 3, 2015 hey guys, im wondering how to determine the tuning of a sealed section of a 4th order. i know sealed boxes dont ecactly have a "tuning" but ive heard they have an Fs. so in a 4th order, how do you get one to play really low? like below 20hz. ive also heard its good to tune the ported section to the sealed sections Fs. ive had a good amount of experiance with 4th orders so im just seeing how much of this is true. im wanting to convert my current 6th order wall into a 4th order for 3-4 FI SP4 18s and want it to play down to 20hz or lower. is there a formula for determining the Fs (tuning) of a sealed section of a 4th order? thanks for any input! Link to comment Share on other sites More sharing options...
Massivespl Posted November 3, 2015 Report Share Posted November 3, 2015 Build your shell and sealed side.. Put your woofers in and run a sweap to see Your res freq without the loading wall on. Then tune the ported side to what your sealed side res freq. a good place to start for port area is half the cone area ur using and go from there... Most people want there seal side to be about 45-49hz and they will depend on the size of your sealed side. c-pillar flat wall 157.11db on music 2 crossfire 8k 4 NSV3 18s 4 crescendo 10s 4 Rockford pro 6.5s Quad excessive amperage 350alts 4 juicebox 3100s Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted November 3, 2015 Report Share Posted November 3, 2015 hey guys, im wondering how to determine the tuning of a sealed section of a 4th order. i know sealed boxes dont ecactly have a "tuning" but ive heard they have an Fs. so in a 4th order, how do you get one to play really low? like below 20hz. ive also heard its good to tune the ported section to the sealed sections Fs. ive had a good amount of experiance with 4th orders so im just seeing how much of this is true. im wanting to convert my current 6th order wall into a 4th order for 3-4 FI SP4 18s and want it to play down to 20hz or lower. is there a formula for determining the Fs (tuning) of a sealed section of a 4th order? thanks for any input! So, like you said, sealed boxes don't really have a "tuning", what they do have is a sealed resonance. We all know subs have a free air resonant frequency (Fs), when you put them in a box, that resonant frequency gets raised and is called Fc. If you know the specs on your subs and the size of your box you calculate Fc, here is an online calculator that will do it for you, alternatively you can use software like WinISD to do it: http://www.carstereo.com/help/Articles.cfm?id=30 If you have the ability to do an impedance sweep you can measure your Fc by looking for the frequency where impedance spikes. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
db_speakerbox Posted November 4, 2015 Report Share Posted November 4, 2015 Well that saves a lot of time. I've always done the formula out by hand. Thought about writing a script for the calcs but someone saved me the trouble. Thanks for the link! Dylan, have you even sealed off your wall yet? Link to comment Share on other sites More sharing options...
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