[sdiy] Ms20 filter clone PBC?

[Ian Fritz]

At 01:11 PM 2/27/2008, JH. wrote:
> >I remember coming up with similar conclusions, that the HP is actually
> >more of a one pole.
>
>No, it's still a 2-pole HPF, even though it's 6dB/Oct in HPF mode.
>Must be a zero exactly compensating one of the (real) poles (as long as no
>feedback is applied).

Right.  No matter what particular transfer function you calculate, you 
always get the same second order resonant denominator.  If you take the 
output from the *other* stage in HP mode, then the slope *is* 12 
dB/Oct.  But then the transfer function is proportional to the feedback 
gain. (Exercise for the reader.)

You can also reconfigure the HP so that it is the proper dual to the LP, 
and then, of course, you also get a 12 dB/Oct slope.  That's why I asked my 
original question.  You guys *could* have done it that way if you wanted 
to, so based on the "12 dB/Oct" statement, I thought maybe you did.  :-)

   Ian