you can obtain Fo by blocking the port(s)


if you don't want to pull the woofs and measure Fs...yes, you can't even count on that being XX Hz., and 1 Hz. either way will skew your answer for Fb. The "twin peaks" Fl and Fh are easy to determine. Signal generator calibration should be verified at 60Hz., then should be OK across the region you will need the Hz. values for the formulas.
This is an important area to "tweak" if you find things are not what you thought. I think the Ql of the enclosure also effects this, and each box is different regarding how "tight" the ultimate construction is. No sim can tell whether or not the horn and woofer flanges are air tight 100%. Sam


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