We can use the recirculating and non-recirculating filters developed here to
create a
*compound filter* by putting several elementary ones in series. If the parameters
of the non-recirculating ones (of the first type) are
and those of the recirculating ones are
, then putting
them all in series, in any order, will give the transfer function:

The frequency response of the resulting compound filter is the product of those of the elementary ones. (One could also combine elementary filters by adding their outputs, or making more complicated networks of them; but for most purposes the series configuration is the easiest one to work with.)

Miller Puckette 2006-12-30