Frequently Asked Questions

When using the SoundTrack LxT or Model 831 with a ¼” pressure microphone (377B10) you also need a ½” to ¼” adaptor for the preamplifier (ADP043) and another one for the CAL200 calibrator (ADP109).

Note: Part numbers and firmware revisions are subject to change. Please contact Larson Davis for current part numbers and firmware revisions.

The recommended preamplifiers are the PRMLXT1 for the LxT and the PRM831 for the 831.

The TOOLS – CALIBRATION section has different screens: Calibrate, History, Sensitivity, Certification and (in the 831 only) an E.A. Check screen and an E.A. History screen. In the sensitivity screen you select the 377B10. After calibration you will see the screens as shown on the LxT (left) and the 831 (right).

       New Peak Level shown ( 177.9 dBpk) 

The peak overload level is the maximum level at the preamplifier that will produce an electrical overload. This level may exceed the maximum sound pressure level the chosen microphone is capable of measuring. Please consult the microphone data sheet for the maximum level for your microphone.

The sequence below shows how to move from the ½” microphone to the ¼” microphone, during the calibration. Sequence of screens (LxT) when changing from ½” free-field microphone (377B02) to a ¼” pressure microphone (377B10).

Sequence of screens (831) when changing from ½” free-field microphone (377B02) to a ¼” pressure microphone (377B10)

The Calibration outside normal range message may or may not appear depending on the nominal sensitivity (user selectable in the 831). Refer to the manual where the valid range is shown. This warning is intended and allows to detect a larger than normal change. There is no problem in accepting the change. (If you recalibrate with a 50mV/Pa microphone, your reference will be again the old one).