I am encoding a mono file to mp3 with Lame and a bitrate of 80, and a stereo file with a bitrate of 160.
I'm using preset cbr.
Since the bitrate per channel is the same in both cases, I expect the lowpass to be the same, but it is not.
See here for more details : http://www.hydrogenaudio.org/forums/index.php?showtopic=93864
Forgot to mention my setup:
Ubuntu 10.10 x64
Lame 3.98.4