Dear all,
recently, i've built a gainclone based on an lm1876, as suggested in the datasheet. it seems to work fine, apart from one strange problem: when I plug in my laptop, i notice an audible, though not very loud 50Hz-hum. as soon as I unplug the laptop from the amplifier, the amp is dead quiet, with no audible hum at all.
The laptop plugged in my faithful old denon-amp doesn't hum at all.
Of course i'm using shielded cable.
Does anybody have an idea? Should I disconnect the grounded shield from the cable on the amp side? But in this case, i would lose the reference, wouldn't I?
I'm thankful for any advice!
recently, i've built a gainclone based on an lm1876, as suggested in the datasheet. it seems to work fine, apart from one strange problem: when I plug in my laptop, i notice an audible, though not very loud 50Hz-hum. as soon as I unplug the laptop from the amplifier, the amp is dead quiet, with no audible hum at all.
The laptop plugged in my faithful old denon-amp doesn't hum at all.
Of course i'm using shielded cable.
Does anybody have an idea? Should I disconnect the grounded shield from the cable on the amp side? But in this case, i would lose the reference, wouldn't I?
I'm thankful for any advice!
i guess that the laptop is earthed somehow - i'm not sure about that.
my amplifier - ehm, good question. it's not in an enclosure, and the ground reference is the middle of the two secondaries on the transformer. could be that the amp is floating
but then - it should be grounded via the connection to the laptop.
anyway - i'll ground the amp and see if the problem is gone then.
my amplifier - ehm, good question. it's not in an enclosure, and the ground reference is the middle of the two secondaries on the transformer. could be that the amp is floating
but then - it should be grounded via the connection to the laptop.
anyway - i'll ground the amp and see if the problem is gone then.
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