lost slot port formulas
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=32963
Printed Date: September 09, 2025 at 2:02 PM
Topic: lost slot port formulas
Posted By: italnpimp59
Subject: lost slot port formulas
Date Posted: May 30, 2004 at 12:34 AM
i used to have all the formulas for calculating and tuning slot-ported boxes in programs i made for my graphing calculator, well i lost the calculator and cant find the formulas anywhere. if someone would give them to me i would really appreciate it. i need the tuning frequency, peak frequency, and the 3db rolloff frequency. and the dB at any given frequency so i can make a graph and see what kind of sound this box will produce at all frequencies. thanks in advance!!
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Replies:
Posted By: DYohn
Date Posted: May 30, 2004 at 11:39 AM
Posted By: italnpimp59
Date Posted: May 30, 2004 at 7:44 PM
that only has the formula for tuning frequency, do you know where i can get the others? thanks for that one though!
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Posted By: bdl666
Date Posted: May 31, 2004 at 3:38 AM
I can't find my books now, but I'll keep looking for them. In the mean time try this program out. https://www.linearteam.dk/default.aspx?pageid=winisdpro It does what you need and more. It even has a signal generator and it can plot graphs for spl, impedance, impedance phase, group delay, maximum xpl, maximum power, and a lot more. Plus it's free.
Posted By: italnpimp59
Date Posted: May 31, 2004 at 1:10 PM
wow that program is awesome, thanks alot for your help man!!!  -------------
Posted By: italnpimp59
Date Posted: May 31, 2004 at 1:36 PM
oh one question about that program, is there a way to input my own dimensions for slot ports and it can figure out the length it needs to be? it has defaulf 1.85,2.86,3.23,4.02,5.51 for length and width and i have to choose. i want to build a box with suppose two 2 inch by 15 inch slot ports and i want it to find out the length, is there a way to do that?
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Posted By: sandt38
Date Posted: May 31, 2004 at 4:55 PM
Sure, just override the default value and add your own value. Select your desired port tune and it will calculate the port length. Also of note, it has a vent mack calculator to let you know if you will suffer port noise.
Be sure the parameters are in the correct english/metric format as well.
ISD is a great freeware. Not perfect, but really easy and really close.
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