CLIOwin 6.5 PCI User's Manual - Audiomatica Srl

13.4 I SENSE
Requires Audiomatica CLIOQC Amplifier and Switch Box model 2, 3 or 4. It is a simplified
Constant Voltage method. Simplification arises as both device gain and sensing resistor
(around 0.1 Ohm) is known. Fig.13.9 shows the CLIOQC Software Control Dialog Box.
I Sense should be selected.
Fig.13.10 shows required connections.
Figure 13.9
INPUT A
CLIO
INPUT B
OUTPUT A
OUTPUT B
LPT PORT
CLIOQC AMPLIFIER&SWITCHBOX
BLACK
RED
GAIN
I SENSE
FROM CLIO
INPUT 1
INPUT 2
INPUT N
GAIN=10dB(Model 1,2&3)
GAIN=20dB(Model 4)
TO CLIO
Figure13.10
Before proceeding, whatever in MLS or Sinusoidal, remember to go in the Settings Dialog
and select I Sense under Impedance. CLIO’s output level has to be set to a much lower
level than in Internal Mode. We have seen before that with 10dBu out we had 0.316V
at speaker terminals at resonance. Should you let this level you would have 7.75V at
any Frequency! -20 to -30 dBu are reasonable output level to start with. The CLIOQC
Amplifier gain is 10dB(Model 2&3) or 20dB(Model 4); it therefore multiply CLIO’s output
by 3.16(Model 2&3) or 10(Model 4). As the output impedance is close to 0 no further
attenuation occurs once the speaker is connected. Finally we deal with measuring
accuracy in this case. The sensing resistor value has been stated as around 0.1 Ohm.
It is very difficult to keep such a low value within a reasonable tolerance and therefore
the real value is going to change between units. The default value that comes is 0.127
Ohm. User can further adjust this value using a reference resistor of known value in the
10 Ohm range (the real value can be eventually measured with high accuracy using
internal mode). Simply take an impedance measurement of the known resistor and
adjust the I Sense value displayed multiplying it by the ratio between the know resistor
132 Chapter 13 - Measuring impedance and T&S parameters