There is a preamp and 4th order 1.0 Hz, low pass filter schematic by A.S. 
Loomis at http://www.info2000.net/~aloomis/seisfilt.htm.  Has anyone had 
experience with this circuit?  Is it possible to change it from a 1.0 Hz low 
pass filter to a 10 Hz low pass filter?  If so, what component values should 
be changed to accomplish this?  I assume it is a good design.
Any assistance would be very much appreciated.
Jim Allen
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