[Ardour-Users] Removing hum from track

[Ralf Mardorf]

On Fri, 28 Apr 2017 14:43:50 -0400, Al Thompson wrote:
>Everyone is missing the simplest, least obtrusive method to eliminate
>60Hz hum on multitrack.  Just flip the phase of some of the tracks.  As
>long as the tracks aren't related to each other (i.e.- stereo pairs)
>there should be no adverse affect, and you won't have to kill low end
>response.

Hi,

this unlikely works very good, if at all.

Assuming the hum on different tracks would be completely in sync, so
that inverting the phase would cancel out the hum, it still requires
that the hum and inverted hum have the same energy. In reality
the hum of several tracks neither is in sync, nor do they have the same
energy and apart from this the hum could be some kind of modulated,
resp. interacting with the wanted signal.

The situation of recoded individual recorded and mixed tracks, is
completely different to the situation of a balanced cable.

Regards,
Ralf