CLIOwin 6.5 PCI User's Manual - Audiomatica Srl

Now we can save our complete results and proceed with the Delta Compliance. The free
air derived data are already in memory and we can deal with the last part of the
procedure only, 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 MSE (MINIMUM SQUARE ERROR)
With this option checked, TS 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 accuracy advantage if the driver impedance fit 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 MSE differ substantially) he/
she must be warned that the entire concept of TS parameters has loosen its usefulness.
This often happens with tweeters, woofer whose impedance has been measured at high
level, defective devices.
142 Chapter 13 - Measuring impedance and T&S parameters