Clearly if the frequency changes it is not 60 Hz. Is there a chance that it is a feedback of some sort? I have run into problems when had both the input and output selected, but do not recall the details as it was a few years ago.
On Wed, Jun 21, 2017 at 10:10 PM, John Jason Jordan <joh...@gmx.com> wrote: > On Wed, 21 Jun 2017 15:45:29 -0700 > Denis Heidtmann <denis.heidtm...@gmail.com> dijo: > > >I do not know much about what you describe, but you could answer the > >frequency issue by recording the sound into Audacity on the laptop. > >(Assuming you do not have a 'scope.) > > > >Is there a chance that the connections which produce the hum include > >two different AC powered devices with a (not quite) common ground? > > Since my original message I have discovered that the hum goes away > on the desktop if I turn off the right channel in Pulseaudio (the movie > has only stereo, not 5.1). I have no idea what this means. > > I also compared all the settings in Pulseaudio on the laptop to the > settings on the desktop. I didn't see any differences, except that > some are different because the two computers have different audio > processors, plus I don't know what all the settings mean. > > As for the frequency, I note that it goes up and down when I change > settings in Pulseaudio. Even at its lowest it is higher than 60 Hz, so > I doubt very much that it is related to household AC power. Besides, AC > power might affect the stereo or the audio cables connecting to it, but > the computer? After going through the power supply and its rectifiers? > I could check it out in Audacity, but I doubt that doing so would > reveal much. > > _______________________________________________ > PLUG mailing list > PLUG@lists.pdxlinux.org > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list PLUG@lists.pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug