User`s manual

13.4 I SENSE
This requires Audiomatica CLIOQC Amplifier and Switch Box model 2, 3 4 or 5. 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.
Figure 13.9
Fig.13.10 shows required connections.
OUTPUT A
CLIO
LPT PORT
CLIOQC AMPLIFIER&SWITCHBOX
INPUT A
INPUT 1
INPUT 2
OUTPUT B
INPUT B
INPUT N
I SENSE
FROM CLIO
TO CLIO
RED
BLACK
GAIN=10dB(Model 1,2&3)
GAIN
GAIN=20dB(Model 4)
Figure13.10
Before proceeding, whether in MLS or Sinusoidal, remember to go into 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 the speaker terminals at resonance. Should you keep this level
you would have 7.75V at any Frequency! -20 to - 30 dBu are reasonable output
levels to start with. The CLIOQC Amplifier gain is 10dB (Model 2&3), 20dB (Model
4) or 26dB (Model 5); it therefore multiplies CLIO’s output by 3.16 (Model 2&3), 10
(Model 4) or 20 (Model 5). As the output impedance is close to 0 no further
attenuation occurs once the speaker is connected. Finally we shall 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 is used is 0.127 Ohm. The 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 the internal mode). Simply take an
impedance measurement of the known resistor and adjust the I Sense value
186 13 MEASURING IMPEDANCE AND T&S PARAMETERS