CLIOwin 7 PCI User's Manual - Audiomatica

13.4 I SENSE
This 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, 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) or 20dB (Model 4); it therefore
multiplies 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
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 displayed multiplying it by the ratio
162 Chapter 13 - Measuring impedance and T&S parameters