Class Project using Excel

[901Fixer]

I have a small school project using Excel to make a page where different variables can be input so the desired answers/output can be found. I thought about doing it using T/S parameters to find a simple box volume, vented or not and vent size. Then an area to input dimensions so as to figure box volume including the vent and driver displacement. I can do the math for the volume calculation and I know there are plenty of sites where I can model a particular driver and get volumes and vent size but I'll need to know what T/S parameters are needed to make my own table. The data produced doesn't have to be perfectly accurate, I just have to show I can configure different cells to calculate using data from others etc. I'll keep it simple and do it for just sealed and vented enclosures, nothing too fancy. Hopefully after doing this I'll better remember some of the important specs of a speaker that go into it's enclosure design.

Any input on this is appreciated or other suggestions.

[Glowbug]

The Subwoofer DIY Page v1.1 - Sealed Systems: Box Calculations

The Subwoofer DIY Page - Ported Systems: Box Calculations

Is that what you needed?

Excel's a big rabbit hole...

[901Fixer]

Thank you very much Sir, that should keep me busy for awhile. The point of this project is to demonstrate how to configure cells and make them use info in other cells with IF or And restrictions etc. Excel is pretty new to me so this will be interesting. I can always simplify things if it gets overly complicated, not that that ever happens with DIY Audio projects.

[901Fixer]

How do I derive a value for Qtc? It is the total Q of system at resonant frequency but how do I derive that from the other T/S parameters?

[rjbond3rd]

These formulas, which I harvested from the Internets, may be (a) incorrect, and (b) out of context, and I can't vouch for them:

Qtc = Qms * sqrt( (Vas/Vb)+1) )
Qtc = Qts * ( ( Vas / Vb ) + 1 ) ^.5 (where ^ means "raised to the power of")

Not vouching for the accuracy!

[tsmith1315]

From a design perspective... Specify a desired Qtc, and here's the box volume needed to (hopefully) attain it.

Vb = Vas / ((Qtc/Qts)^2-1)

Rearranged it is indeed:

Qtc = Qts * sqrt((Vas/Vb) + 1),

but that's working backwards to evaluate driver choices in a predetermined box.

[901Fixer]

In order to find Qr and then F3 I need to know Qtc according to this site:

The Subwoofer DIY Page v1.1 - Sealed Systems: Box Calculations

I'm making a similar but simpler Excel page so as to demonstrate the formatting of cells using If or And statements etc. The 4 T/S measurements needed are Vas, Qts, Fs and Qtc. I realize this information may not produce accurate results but since the project is more about the ins and outs of Excel the details aren't as important.

The page will have 4 boxes to input Vas, Qts, Fs and Qtc unless I just use a set value for Qtc. The above Qtc = Qts * sqrt((Vas/Vb)+1 will work also.