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Disable magnet fix subwoofer humming

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muguen

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I bought cheap 5.1 speakers and when ever I connected to the power I start to hear this strong humming, so I opened the subwoofer and disconnected the wire connect to the magnet from the circuit this basically disables the subwoofer functionality.

Also whenever I connect and disconnect the subwoofer it makes this big BOOM sound..

Is there any way to fix this without disabling the magnet?

Thank you
 
But the speakers still work as well as the subwoofer if I connect the wire back to where it was.... I disconnected the wire that goes to the magnet just to disable the subwoofer functionality therefore the humming disappears.

I think the humming is coming from harmonics or noise coming from the circuit board which r being amplified.

So I thought about building a small pcb board with a few capacitor connected in parallel and connect it between the circuit board and the wire connected to the magnet to absorb the harmonics .. This will basically act as filter. However I don't know what capacitor values to use.

Will this work?
 
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But the speakers still work as well as the subwoofer if I connect the wire back to where it was.... I disconnected the wire that goes to the magnet just to disable the subwoofer functionality therefore the humming disappears.

I think the humming is coming from harmonics or noise coming from the circuit board which r being amplified.

So I thought about building a small pcb board with a few capacitor connected in parallel and connect it between the circuit board and the wire connected to the magnet to absorb the harmonics .. This will basically act as filter. However I don't know what capacitor values to use.

Will this work?

No - the amplifier is blown, that's why it hums, and that's why you get a 'boom' when you connect the speaker.

Measure the DC voltage on the output of the amplifier - it should be zero, within a few millivolts - this won't be.
 
The hum is probably mains hum from the amplifier (nothing to do with harmonics). The amp is either poorly designed or is faulty. The parallel-connected caps are unlikely to improve things.
If the speaker is driven via a large coupling capacitor the loud pop on connecting the speaker to the cap is to be expected.
 
i agree the amplifier is blown. the thump you hear is DC offset on the amp output, and the hum is power supply ripple riding on the DC. these are classic symptoms of a shorted amplifier. it's possible the woofer is bad as well, unless the wattage of the woofer exceeds the capabilities of the amp's power supply by a large margin.
 
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