CLIOwin 7 PCI User's Manual - Audiomatica

utton. Any process you execute can be saved to disk and will have "mpro" extension.
This allows you to recall any value or file path later on by loading this file again. Suppose
you have a small production of ten speakers that you want to test against a previous
produced reference which you know is fine. You just have to define and save a process
that divides the current data with the reference. Testing a device against itself should
produce a flat line, within the frequency range of the device, and this should be checked
before saving the process. When you need to check your batch you just recall your
process. This will activate the Automatic Process button. When this button is activated
any subsequent measurement is processed before it is displayed. The next process we
will consider is the dBSPL/Watt. It requires a file and an impedance value and allows
us to obtain a frequency response plot referred to 1W at the speaker terminal whatever
the real measurement level is. To make this possible an electrical measurement at the
speaker terminal (power amplifier output) must be taken, with dBV as y-scale, and used
as a reference file. A value of impedance is also necessary that allows CLIO to convert
voltage to power. We will go through the entire procedure using the tweeter of the
previous examples. Since what we are looking for is the response in a 1W-1m condition
we have to move the microphone to a distance of 1m from the tweeter (it was at
69.14cm). The 1m condition can be set directly with a meter. Fig.10.32 shows the 1m
measurement in black and the previous one in red. Signal level at speaker terminal is
unchanged. The average difference being 3.3dB.
30.0
CLIO
180.0
dBV
Deg
20.0 108.0
10.0 36.0
0.0 -36.0
-10.0 -108.0
Figure 10.32 and 10.33
-20.0 -180.0
20 Hz
100 1k 10k 20k
We now connect CLIO’s input to the speaker terminals and change the y-scale to dBV,
do not change CLIO’s output level, we then obtain Fig.10.33. This is a nearly flat line
that indicates the voltage delivered to the speaker. Remember to save the measurement
to disk. It is worth pointing out that deviation from linearity in this curve due to the power
amp or cable would be compensated for by this procedure. Now we reload the response
at 1m, go to the Process Dialog that will appear as in Fig.10.34.
Figure 10.34
We set the impedance to 8 ohm as this is the nominal impedance of the tweeter. Clicking
OK we obtain Fig.10.35, which is the final result.
126 Chapter 10 - MLS