CLIOwin 6.5 PCI User's Manual - Audiomatica Srl

13.3.2 SETTING THE RIGHT LEVEL
The five curves of Fig.13.4 are taken at 5 different output levels, ranging from 10dBu
to -10dBu in 5dB steps. The red curve refers to +10dBu, the blue to +5dBu, the
remaining are substantially overlapped.
25.0
CLIO
180.0
Ohm
Deg
20.0 108.0
15.0 36.0
10.0 -36.0
5.0 -108.0
0.0 -180.0
10 100
Hz
Figure 13.4
It turns out that going from linear device to loudspeakers makes the life harder even
if, probably, more interesting. Deriving the principals TS Parameters from the five
curves yields to Table 13.1
Fs Qms Qes Qts
+10dBu 69.244 3.105 0.609 0.5094
+5dBu 71.63 3.6461 0.6643 0.5619
0dBu 72.9912 3.986 0.695 0.5920
-5dBu 73.5429 4.1663 0.7147 .61
-10dBu 73.82 4.227 0.7218 0.6166
Table 13.1
Values from 0dBu to -10dBu are in optimum agreement and this set the maximum level
to be used to 0dBu. Interestingly enough, Internal Mode is the less sensitive to output
level. We will go further on this topic relaying on CLIO being a complete and powerful
audio measuring system. Without changing connections we will use CLIO’s FFT and
Signal Generator to evaluate the distortion current at resonance at 10dBu. Fig.13.5
shows the spectrum in this condition. The second harmonic is 56dB lower than the
fundamental, which is 0.158% distortion. Even at 10dBu we are by far in the linear
region of the loudspeaker motor. However what we have seen above, clearly states
10dBu are a quite high level for this device.
Chapter 13 - Measuring impedance and T&S parameters 129