Fons Adriaensen <fons@xxxxxxxxxxxxxx> writes: > On Tue, Jun 08, 2021 at 03:54:31PM -0400, Brandon Hale wrote: > >> > Don't do this - ever. You could easily destroy your mic input(s) if the laptop >> > power supply isn't as isolated as it should be (quite common), or the laptop's >> > headphone output if there is phantom power on the mic input. >> >> That was my bad in assuming he's not using the microphone inputs, but the >> Behringer's aux inputs that have quarter inch jacks. > > Wouldn't make much difference. If the laptop is mains powered and happens > not to be grounded you could easily have a hundred volts on the laptop's > 'ground'. High impedance, almost 'static' and hence not lethal to humans, > but more than enough to kill an audio input. Watched it happen more than > once, the more spectacular case was when a certain university professor > deciced to cut of the ground connection of his laptop's power supply in > order to get rid of the hum. He didn't do that again. Puts me back when a physics professor in a lecture did not get a volunteer for entering a Faraday cage connected to a band generator producing impressive sparks and then went in himself. That was at a time when Lavalier microphones were not yet customarily wireless... Static electricity, sure, and the assistant stopped the band generator almost immediately again. It didn't help getting volunteers... > Anyway, without transformer isolation and separate grounds you will > never get rid of the broadband interference generated by both the > laptop itself and its switching power supply. -- David Kastrup _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx https://lists.linuxaudio.org/listinfo/linux-audio-user
