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Old 25th April 2012, 03:04 PM   #1
Andre42 is offline Andre42  Germany
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Default Vented enclosure design - SBB4 calculations

My search is on the mathematical specification of the SBB4 alignment.

I retraced the calculation of QB3 alignment based on filter theory.

The filter coefficiants are given by:
Click the image to open in full size.

The frequency response of a vented enclosure is given by:
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The requirement for QB3 alignment is given by:
Click the image to open in full size.Click the image to open in full size.

For given TS parameter (F_s, V_as, Q_ts) and assumed leakage (Q_L) the corresponding coefficiants and the associated B can be calculated. I inserted those calculations in a little Excel sheet. Of course the resulting box volume and Helmholtz frequency are calculated too.

Now I would like to calculate the SBB4 alignment, but I can't find a mathematical definition in the web.

Help is much appreciated.

Last edited by Andre42; 27th April 2012 at 06:22 AM. Reason: visibility of images
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Old 26th April 2012, 03:13 AM   #2
Ron E is offline Ron E  United States
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I've never found one.

I did a curve fit of one not sure if it is SBB4 or BB4?

I think this is Ql=7
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Old 27th April 2012, 06:19 AM   #3
Andre42 is offline Andre42  Germany
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In David Weems book " Designing, Building, and Testing your own Speaker System" there is a chart for SSB4 but no calculation. Your formula might match this chart - I will check.

Weems also mentioned that SSB4 alignment is from Robert Bullock. So my next step is to look into Robert Bullock's papers, which can be bought as "Bullock on Boxes".
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