Calculating QTC of an enclosure

[NB50 206]

I would like to know what is the most accurate way to calculate QTC of a sealed enclosure.

For example in WinISD i have the specs for my speaker in there and in a 1.2ft^3 it gives me a QTC of .704

In BBP6 with a 1.2ft^3 enclosure it gives me a QTC of .56

And Calculating it from the formulas on these two sites.

http://www.diysubwoofers.org/sld/sealed1.htm

http://www.carstereo.com/help/Articles.cfm?id=29

They give me a QTC of .62 with a 1.2ft^3 enclosure.

So I would like to know which way is right?

[Adrian_D 520]

For sealed enclosures I do the math by hand or use this calculator :

http://www.ajdesigner.com/subwooferonline/sealedonline.php

[NB50 206]

That is the same result that I got from the links I gave. Appears the formulas are from the Loudspeaker Design Cookbook. Guess I will use that from now on.

I wonder how WinISD and BBP6 calculates them and why they are different?

[Adrian_D 520]

BBP6 has an option to use normal ecuations or ecuations that take into account fill. I suspect that's why it gives skewed results.

Not sure on why winisd works bad.

[Aaron Clinton 2,372]

I have used the "Speaker Enclosure Calculations" portion of bcae1.com in the past.

[NB50 206]

BBP6 has an option to use normal ecuations or ecuations that take into account fill. I suspect that's why it gives skewed results.

Not sure on why winisd works bad.

Opps should have mentioned that is turned off when the calculations were made.

Heres screen shots.

WinISD

BBP6 (Just noticed Xmax was wrong but that doesn't matter)

Calculated

Edited January 20, 2009 by bromo