Mystery Hum From My Sub-Woofer

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Bananabob

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#289046 9-Aug-2021 15:14

Over the last two to three years I have several instances of what sounds like a 50 cycle hum coming from my sub-woofer. This is not your normal 50 cycle hum as it actually activates the sub-woofer and sounds very loud. I have the sub-woofer set to activate when required. This noise usually occurs in the middle of the night. Last night I was woken about 5.00AM with what sounded like a car engine warming up in my lounge. I have a feeling that this mystery is a result of either a power fluctuation or the ripple control for hot water as it happens very rarely. Anyone have any ideas?

FineWine

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Nurse (R)

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#2757295 9-Aug-2021 15:40

a quick google search - hum in powered subwoofer - came up with just a few answers this.

Whilst the difficult we can do immediately, the impossible takes a bit longer. However, miracles you will have to wait for.

Bananabob

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#2757298 9-Aug-2021 15:44

FineWine:

a quick google search - hum in powered subwoofer - came up with just a few answers this.

As found in the first link:

A conspicuous, persistent hum emanates from the subwoofer, and it shows no signs of going away.

This is not my problem. My problem is a hum that starts up all on its own.

Oblivian

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#2757303 9-Aug-2021 15:54

At previous place, although not for a long period like yours, my sub would go THUD and turn on with LFE activation whenever the freeze in the garage on the same circuit would kick in.

I forked out for a filtering powerboard (think they have some basic caps in them) which made it vanish. Got a UPS you can hang it off for a period and see if it is something like odd signalling that it will even out?

Probably not the greatest solution, but if it's only during annoying a/hrs could always Stick it on a timed switch adaptor? :)

tehgerbil

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#2757305 9-Aug-2021 15:54

How is it connected to power - to wall or 4 way?

FineWine

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Nurse (R)

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#2757306 9-Aug-2021 15:55

This forum article might be helpful - Intermittent Subwoofer Hum

Whilst the difficult we can do immediately, the impossible takes a bit longer. However, miracles you will have to wait for.

Bananabob

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#2757307 9-Aug-2021 15:58

tehgerbil:

How is it connected to power - to wall or 4 way?

4 Way

Bananabob

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#2757308 9-Aug-2021 15:59

FineWine:

This forum article might be helpful - Intermittent Subwoofer Hum

That describes the problem very well thanks. I will take a look into it.

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#2758383 11-Aug-2021 09:41

Bananabob:

This noise usually occurs in the middle of the night. Last night I was woken about 5.00AM with what sounded like a car engine warming up in my lounge.

Just turn it off when not used .
If its that loud then its a fault somewhere (or bad design)

Mains hum wouldnt be very loud , earth loop issues wouldnt be that loud either (and wouldnt be intermittent)
Its a fault somewhere (or bad design ) , even if somehow triggered to turn on late at night it should stay fairly quiet without any real audio input .

You could try connecting the sub via optical rather than RCA cables .
Or replace the RCA cables going into it .