Quote Originally Posted by Jeff B. View Post
The device does not know what it is testing, it is simply measuring the impedance. Theile-Small parameters are defined by the impedance plot, and there is math in the program to calculate them from the impedance curve it measured.

Again, 95% of the time it won't matter which way you position the driver, the measurements will be within a small margin of error of each other either way. But it is simply not correct to say the device was made for drivers in a particular orientation - it just measures impedance and processes the data from there. At that point it comes down to how the standard forumlas are derived, and they were derived with the voice coil centered, so if it is pulled off-center horizontally, then that reduces the accuracy of the data. It is as simple as that.

As far as the data shown in this thread for the 15" driver - the horizontal orientation is fine.

Jeff B.
When you refer to the 15" drivers are you referring to the WT3 results I attacked to one of my posts? In the vertical position the Vas was 18.21 cubic feet (515 liters) and in the horizontal position is was 13.16 cubic feet (373 liters).

The vertical WT3 derived SPL of 91.71 is closer to the mfg spec of 92.8 SPL whereas the horizontal WT3 derived SPL of 90.52 is further away from the mfg spec of 92.8.

The vertical WT3 Vas of 515 liters is further away from the mfg spec of 305.8 liters whereas the horizontal WT3 Vas of 373 liters is closer to the mfg spec of 305.8 liters.

Well, my rule of thumb is to call a company three times and if I get the same answer 2-3 times out of 3, I assume I am on the right track.