The Guralp CMG-DM24 Mk3 Datalogger has two preamp options:
As with all Guralp instruments, the manufacturer's calibration sheet for each serial number will list that instrument's most accurate bit weight. When updating a datalogger sensitivity using a nominal response, not only is it necessary to change the value in stage 3 (the A/D stage), but also to recalculate the stage 0 sensitivity that represents the product of all stage gains.
CMG-DM24 fixed gain
CMG-DM24 variable gain
Mary Templeton 4/5/2011