Humming sound from my KEF C4 Subwoofer

[srijith]

Hi Guys,

I have recently started hearing humming noise from my sub-woofer though its very low but still it annoys me. The sound emanates once the AVR powers the sub-woofer on playing music.

The humming still exists upon switching off the AVR.

Your advise needed.........

Will resetting the AVR solve the issue. And how do i reset the AVR(DENON 1312).

Preliminary checks done:

Tried reconnecting all the connections of my Speakers, still no respite.

Systems are Denon 1312 AVR, FL FR KEF Q300, Sub KEF C4

Regards,
Sree

 

[vivek.saikia]

Hi Guys,

I have recently started hearing humming noise from my sub-woofer though its very low but still it annoys me. The sound emanates once the AVR powers the sub-woofer on playing music.

The humming still exists upon switching off the AVR.

Your advise needed.........

Will resetting the AVR solve the issue. And how do i reset the AVR(DENON 1312).

Preliminary checks done:

Tried reconnecting all the connections of my Speakers, still no respite.

Systems are Denon 1312 AVR, FL FR KEF Q300, Sub KEF C4

Regards,
Sree

I too had a similar issue. Refer to my thread link below:

http://www.hifivision.com/diy/11979-sos-eliminating-humming-noise-active-subwoofer.html

A small "jugaad" fixed the problem though. I connected the speaker ground to the body of the plate amp and the humming noise was gone :lol:

 

[Sunderpalanivel]

Buy a sub woofer cable that has gound cable and ground it. It will solve the issue

 

[manoj.p]

Or just get a ground loop isolator. Google.

 

[srijith]

Today I will try and power the subwoofer from a different source...Lets see if that works...Also i should remind you that the humming is not very loud only if you put your ears close to sub than can you hear the sound......but it still shouldn't happen

 

[manoj.p]

Then check one more thing as well. Check the gain on the subwoofer amp and the level set for it in the receiver. if the gain on the subwoofer is too much, then the receiver sets it level very low and ends up sending very low signal to the sub. When this low signal is amplified by the sub, you can hear some noise.

If above is found to be true, then reduce the sub gain by few dbs and increase the gain on receiver by same amount. even if you have sub level in the receiver at zero, that will be fine.

 

[Flash]

The humming is purely due to ground loop and nothing else

1. Isolate power cables from subwoofer cable, this will reduce interference

2. Get a well shielded Subwoofer cable. This will completely get rid of the humming sound

 

[Hari Iyer]

Hi Guys,

I have recently started hearing humming noise from my sub-woofer though its very low but still it annoys me. The sound emanates once the AVR powers the sub-woofer on playing music.

The humming still exists upon switching off the AVR.

Your advise needed.........

Will resetting the AVR solve the issue. And how do i reset the AVR(DENON 1312).

Preliminary checks done:

Tried reconnecting all the connections of my Speakers, still no respite.

Systems are Denon 1312 AVR, FL FR KEF Q300, Sub KEF C4

Regards,
Sree

After trying everything mentioned by the FMs if you still find hum then there could be a possibility of an issue with the filter capacitors of the DC power supply of your subwoofer amplifier.There could be a possibility of a leaky capacitors in the powersupply stage. Identify if its a 50Hz power supply hum and if yes then the power supply of the subwoofer could be faulty. Typically if its a small leak then the hum will be very small and will be constant. The hum will start as soon as you turn on the subwoofer with no cables connected too. Usually the cable type hums goes off if you remove the cables.

If you get the hum by just turning on only the subwoofer (remove all connecting cables from AVR for this test), then immediately get it serviced / repaired if its still under warranty.

Regards,

 

[srijith]

Hey hi Hari nice to see you!!!!

Thats what i was about to update you guys.....I think its a cable issue since when i remove the subwoofer cable(with the power cord on) the humming sound goes off....so
filter capacitors of the DC power supply of the subwoofer is OK....Thank God....

Today the service guys will come to see whats the issue...they too were of the opinion that it might be because of the cables......

 

[srijith]

The humming is purely due to ground loop and nothing else

1. Isolate power cables from subwoofer cable, this will reduce interference

2. Get a well shielded Subwoofer cable. This will completely get rid of the humming sound

Is it because the subwoofer cable and power line cable are entangled with each other......this might be the reason...good suggestion....

I will try and isolate the cables and see if this works....

 

[sound1]

BTW, did you get yourself a new samsung LCD TV?

Last time my amp went crazy with the hums. After sometime I realized it was my LCD TV causing the issue. They all are connected to same spike buster. I cut off the earthing of the amp (not safe/recommended) and all is well now.

 

[Hari Iyer]

Is it because the subwoofer cable and power line cable are entangled with each other......this might be the reason...good suggestion....

I will try and isolate the cables and see if this works....

You can also ground both the AVR & subwoofer amp chassis by connecting them with a jumper wire. This will completely remove the hum. I did this for my Denon and subwoofer amp on one of the screws fixed to the chassis.

 

[srijith]

You can also ground both the AVR & subwoofer amp chassis by connecting them with a jumper wire. This will completely remove the hum. I did this for my Denon and subwoofer amp on one of the screws fixed to the chassis.

Can you please post pics on how to ground both the AVR & subwoofer amp chassis by connecting them with a jumper wire.

 

[srijith]

hello Hari...Many congrats to you...you are turely great!!!!!!!

The problem is resolved!!!!!!!!!!!!!!!!!