Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!linus!decvax!harpo!eagle!karn
From: karn@eagle.UUCP (Phil Karn)
Newsgroups: net.audio
Subject: Minor correction
Message-ID: <1082@eagle.UUCP>
Date: Wed, 31-Aug-83 19:05:40 EDT
Article-I.D.: eagle.1082
Posted: Wed Aug 31 19:05:40 1983
Date-Received: Thu, 1-Sep-83 05:49:55 EDT
Lines: 11

Oops, I made a mistake when I said that ALL low or high pass filters
have an ultimate attenuation that is a function only of the filter's
order.  This is only true for all-pole filters, as rabbit!jj pointed
out.  Elliptical (Cauer) filters, which have zeroes in the stop band,
will have an ultimate attenuation of 6 or 0 db/octave depending on
whether the filter is of even or odd order.

However, both Butterworth and Bessel high or low pass filters are
all-pole and have ultimate attenuations of 6 db/octave/order.

Phil