Dayton WT3 not giving correct parameters

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I'm building the Madisound HDS Home theater kit. Though I didn't need to, I tested all 4 woofers (Peerless P870830) with my WT3 using the added mass method. All 4 woofers were nearly identical and figure 1 is a typical pair of impedance sweeps.

The parameters differed somewhat from those published by Peerless, so I wanted to see if the difference would affect the cabinet designs. I imported the impedance curves into Speakerworkshop and calculated the driver parameters in Speakerworkshop. Figure 2 shows the parameters calculated from the same impedance curves by Speakerworkshop and by the WT3 software, and also the published parameters.
I then used Speakerworkshop to design C4/Chebychev enclosures using the parameters Speakerworkshop calculated from the WT3 curves, and using parameters I copied from the Peerless datasheet.
The result? Speakerworkshop designed a 25 liter cabinet with a port tuned to 56Hz and an F3 of 49Hz using parameters calculated from the WT3-derived impedance curves. It designed a 12 liter cabinet tuned to 69Hz with an F3 of 60Hz using the published parameters, which just so happens to be identical to Madisound’s cabinet plans for that kit! (see figure 3)
So I don’t know if I did something wrong, or if the WT3 is not very accurate. Recently epoxy resin leaked all over the WT3 and the scale, and I used water and mineral spirits to get it off. Could I have damaged either? I’m wondering if other people have gotten similar results.


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Those impedance curves looks smooth and undistorted, i don't think there is anything wrong with em.
Many years ago I used to use Clio lite and did similar comparsions, it seemed that softwares calculate parameters differently. Just look att the inductance (Le) value that ARTA/Limp calculates, it differs quite a lot from the value you get from the actual impedance curve and using the LCR-meter function
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