V G wrote: > I'm putting the filters AFTER the low impedance output of an opamp. > Or am I mistaken and the opamp output is high impedance? Oh, I thought you were putting them right at the input. If you don't, then the DC bias will be amplified by the first stage, which may cause clipping there. I guess we don't really know what you're trying to do. Show a schematic so we can all be on the same page. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .