VT RTA-168A/B Manual Rev. 1.5
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the corresponding sound card’s name in the “Device No.” field. By default, Multi-
Instrument will use the computer’s built-in sound card for signal output. Again, the “Device
Model” field must be set to “Sound Card MME”.
Now, if you press the Signal Generator button (see figure above), the Signal Generator panel
will be opened (see figure below). Press the red triangle button at the upper right corner of
the Signal Generator panel, you should hear a 1kHz test tone from the speaker or earphone
connected to the selected playback sound card. Press it again to stop the sound.
1.5 Input of Sound Level Calibration Data and Adjustment of Input Gain
Sound Level Calibration is not required for those relative measurements such as frequency
response, THD, THD+N, IMD, etc.. It is required only if you want to measure the absolute
sound level.
The measurement microphone and the XLR-to-USB sound card have been calibrated in pair
in the factory. The sound level calibration data are provided in a separate sheet inside the
