Hi All,
I'm baffled by a problem I'm having with some audio equipment. I have two active speakers (with built in amplifiers) each takes a two-pin mains connection and an unbalanced RCA input. I have these connected to a laptop, through a 3.5mm jack to RCA breakout tail. There is no earthing terminal on either the laptop or the speakers.
When the laptop is switched on, everything is fine and when nothing is playing, the whole system is silent, however as soon as the laptop switches off (or goes into Sleep mode) there is instantly a VERY LOUD 50hz humm from the speakers. I have tried different devices, and the same occurs, if the unit is powered, no hum from the speakers, if the unit is unpowered, very loud hum from the speakers.
I'm used to dealing with ground loop issues, and normally this sort of thing would be corrected by ensuring all the equipment was on the same earthing point, but none of the kit has earth terminals and all the equipment is plugged into the same multi-socket in any case.
If I disconnect the audio cable from the laptop end - the buzzing remains but is quieter, if I disconnect the audio cable from the speaker end, the hum stops. So from this I am guessing a current is getting induced in the audio cable from the power cable? But if so - why does the humming stop when the source equipment is powered on?
How could I fix this permanently? Another forum suggested buying RCA cables with an earth wire... but there is no-where to attach this on either the speaker or the laptop.
Help!
I'm baffled by a problem I'm having with some audio equipment. I have two active speakers (with built in amplifiers) each takes a two-pin mains connection and an unbalanced RCA input. I have these connected to a laptop, through a 3.5mm jack to RCA breakout tail. There is no earthing terminal on either the laptop or the speakers.
When the laptop is switched on, everything is fine and when nothing is playing, the whole system is silent, however as soon as the laptop switches off (or goes into Sleep mode) there is instantly a VERY LOUD 50hz humm from the speakers. I have tried different devices, and the same occurs, if the unit is powered, no hum from the speakers, if the unit is unpowered, very loud hum from the speakers.
I'm used to dealing with ground loop issues, and normally this sort of thing would be corrected by ensuring all the equipment was on the same earthing point, but none of the kit has earth terminals and all the equipment is plugged into the same multi-socket in any case.
If I disconnect the audio cable from the laptop end - the buzzing remains but is quieter, if I disconnect the audio cable from the speaker end, the hum stops. So from this I am guessing a current is getting induced in the audio cable from the power cable? But if so - why does the humming stop when the source equipment is powered on?
How could I fix this permanently? Another forum suggested buying RCA cables with an earth wire... but there is no-where to attach this on either the speaker or the laptop.
Help!
