User`s manual

13.7.4 T&S STEP BY STEP
Getting T&S requires two impedance measurements. As we will use both methods
we need three, the first relative to the driver in free air, the second to the driver
with a known mass (Delta Mass) added to the cone, the third to the driver loaded
with a known volume (Delta Compliance). Fig.13.20 shows the results of the three
measurements, overlaid in one single graphic.
Audiomatica Srl Sinusoidal 05/07/2001 10.02.11
CH A Ohm Unsmoothed Stepped Delay [ms]: 0.000 Free air File: freeair.sini
10 100 1k 10k 20k10 Hz
50.0
Ohm
180.0
Deg
40.0 108.0
30.0 36.0
20.0 -36.0
10.0 -108.0
0.0 -180.0
CLIO
Figure 13.20
The black curve refers to free air, the red to delta mass, the green to delta
compliance. As you can see adding a mass results in lowering Fs while loading the
cone with a closed volume will increase Fs. Always check this is the case to avoid
errors in the post processing routine. As deriving T&S parameters can be performed
at any subsequent time after the impedance measurements has been taken, we
suggest you save them with meaningful names as well as using the Notes Dialog to
store the measuring conditions as mass weight and/or volume. The last step before
pressing Go in the T&S dialog is to measure both the voice coil DC resistance and
the effective cone diameter in millimeters. In this example they are 6.41 Ohm and
133mm. Finally we select File Data as the data origin and pressing Go we get the
following prompt Dialog
194 13 MEASURING IMPEDANCE AND T&S PARAMETERS