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Subwoofer and humming sound

I have a mordaunt short MS909W Subwoofer that has been hooked to my pioneer receiver for over two years. A week ago a loud humming sound started coming out of the subwoofer and when you change functions or hit mute there is a loud thump. I have not disconnected anything. It just started humming and the subwoofer is not working.

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dunnbiker
  • 8546 Answers

SOURCE: how to connect a mordaunt short ms907 subwoofer?

You feed it the Subwoofer Line Out (if you have one) or the High Level (Speaker) Outputs of an amp or receiver.

All you will get for output from a laptop or other source would be 23-150hz.

Here's the manual.

http://www.mordauntshort.com/assets/documents/MS907W_Manual.pdf

If you feed it speaker-level inputs because you DON"T have a subwoofer Line Out you can drive satellites from your own amp or receiver THROUGH the subwoofer. It doesn't actually drive other speakers, if that's what you're looking for.

The Line Output of the subwoofer would be to feed another amplified subwoofer.

Posted on Apr 27, 2009

  • 63 Answers

SOURCE: subwoofer not working

i think it is a shortage with your cord connecting to you subwoofer

Posted on Sep 27, 2009

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4 Answers

Klh powered subwoofer model ASW10-120B... when you plug in to power... it makes a loud buzzing/humming noise


I would check the caps on the power supply. They are rather large electrolytic capacitors that will look like they burst and/or leaking. When these die, the caps ground and the sub will make a loud buzzing sound. If you are handy with a soldering iron you can replace them yourself. Replace them with the same voltage or a little bigger and same with the size.

If the cap. says 16v 4700pF on it, for example, a 20v 5300pF or a 16v 6200mF cap. will work for this application.

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Jan 05, 2016 | Audio Players & Recorders

1 Answer

Hi my name is Ben. I have a Mordaunt Short home theatre system which is probably 6 yo but has had very little use. On standby mode, the 309W sub started to make a buzzing sound with intermittent louder...


It can be repaired. A transistor shorted and possibly some resistors burned open as well. This is due to an overload causing the transistor to drive hard creating heat and eventually shorting out. The transistor needs to be isolated, removed, and replaced as well as the resistors.

Nov 12, 2010 | Mordaunt Short 309W Subwoofer

1 Answer

309i sub not working


hi ,
2 things to do

1 - the power amp has fail and will need to be looked at
2- your amp could have a sub output faillure

Jul 14, 2010 | Mordaunt Short 309W Subwoofer

2 Answers

Humming sound in subwoofer after it's been playing for a while


It sounds like you are describing an earth loop problem. I won't go into detail in this post, but try an isolation test first. disconnect everything from the reciever except the sub and try connecting say a BATTERY powered mp3 player or cd player to minimise connections to the electrical mains earth. you could also isolate things by taking your sub to a friend's house and trying it on their system.
If it is an earth loop use a process of elimination to find out which two pieces of equipment causes the earth loop. then apply filtering.
you can buy earth loop isolation transformers for about AU$26 and I've used one on my sub myself. Theyhave RCA (phono)plugs on each end and they connect inline with the signal cable to the sub amp.

as for the thumping sound it might be the speaker protection circuitry cutting off the amp to protect the subwoofer speaker from damaged. This might be triggered if the earth loop sound is causing the sub amp to overload and clip.

Failing this there might be a dried out overheated electro capacitor in the amp circuit causing the hum. Hav a chat to your local electronics person, who should be able to spot it!
Hope this puts you on the right track
Happy Hunting!

Jan 07, 2010 | Sunfire Audio Players & Recorders

2 Answers

How to connect a mordaunt short ms907 subwoofer?


I guess you don't have the owner's manual for this?
You can get it here:
MS907 Subwoofer manual
The manual contains connection info.

Apr 27, 2009 | Mordaunt Short MS-308 Subwoofer

2 Answers

Sunfire Subwoofer 110 Noise on input plugin


A few more questions-
Does the sub hum without anything plugged into it except for power? If it makes a real loud hum almost a squeal then I think the rca cable between the receiver and the sub is dead shorted and needs to be replaced. If it's more of a low level hum, then it's a ground hum caused by many things, ie........the receiver and the sub being on different power circuits in the house.......sometimes diconnecting the cable tv feed as it enters the room while the sub is connected and humming to see if it stops........the easy fix sometimes is using a 3 to 2 prong ac adapter but lifting the ground on such a powerful amp could be a fire hazard.

Sep 25, 2008 | Sunfire True Sub MK II Subwoofer

1 Answer

Loud humming sound from subwoofer


just try leaving it unplugged for a while thats what i did and it fixed it

Sep 21, 2008 | KLH PSW8100-8 Subwoofer

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