CLIOwin 7 PCI User's Manual - Audiomatica

We can now save our complete results and proceed with the Delta Compliance. The free
air derived data is already in memory and we can finally deal with the last part of the
procedure, which is nearly the same as before. We will be prompted for volume instead
of weight. Obviously the file we have to choose is relative to the driver loaded with a
known volume (15.1 liters in this case). Here we show the results for the Delta
Compliance method. The two sets of data do agree pretty well.
13.7.4 USING LSE (LEAST SQUARE ERROR)
With this option checked, T&S parameters are calculated in a more sophisticated way.
Basically the parameters obtained in the standard way are used to derive the starting
values for the equivalent electric circuit model. These values are then changed slightly
around the initial value until the best fit between the calculated and measured impedance
curve is found in a large frequency range around resonance. This procedure works fine
and gives an accuracy advantage if the driver impedance fits the Thiele and Small model
pretty well. Unfortunately this is not always the case. Should the user encounter such
cases (if the parameters obtained with and without LSE differ substantially) the user
must be aware that the entire concept of T&S parameters has lost its usefulness. This
often happens with tweeters or woofers whose impedance has been measured at a
high level with defective devices.
172 Chapter 13 - Measuring impedance and T&S parameters