For great flexibility, sharp cut-off, etc., I think that the Rockland 
analog filters are the way to go. With this type of adjustable filter, 
you can easily try different settings to see which is best for you. I 
have a Rockland model 1022F-04.
It is dual channel.  The two channels can be independently set.  
Function:low or high pass, response is Butterworth or RC, attenuation 
slope is 24 db/oct [this is really sharp], there are several models:
model     cut-off range
  01    0.01Hz to 111kHz
  02    0.001Hz to 11.1 kHz
  03    0.1Hz to 111 kHz
  04    0.01 Hz to 11.1 kHz
input is single ended, 10M impedence
gain is 0db or 20 db
Output is single ended 50 ohms impedence

If you want only a single filter, the two sections can be connected in 
series to provide REALLY sharp cut-off or a band-pass filter.

It is rack mount, 5 1/4" hi, 17" wide and 14" deep and weighs 18 lbs.
  Power consumption is less than 10W
I can supply a photocopy of the manual.

There us currently a digital Rockland on ebay but it looks expensive and 
I don't know the specs.  The analog version comes up occasionaly.
I  paid <$200 several years ago on ebay.



Bob



__________________________________________________________

Public Seismic Network Mailing List (PSN-L)