Question about Celestion S8 Subwoofer

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Celestion S8 Subwoofer

Hi folks, My S8 has started humming all the time, with or without the phono lead in, and in all on/off/auto positions. It's been a pretty good sub so far so I'd rather try and fix it than dump it! Could it be a coupling cap or a resistor gone high in the amp? Any help much appreciated! Oberon

Posted by Dave Herd on

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  • Anonymous Jan 02, 2008

    i have the same problem with mine it seems to be the blue relay chattering , voltages and cappies seem ok, the reason for the chatter is unknown anyone out there got a circuit diagram.

  • Anonymous Aug 08, 2008

    I have an S8 with the chattering relay issue and we are not alone - looking about a few forums it is a widespread problem.

    I got hold of the schematice for a kef psw2000 which is broadly similar and after browsing the diagram and a few forums I plan to replace the main smoothing caps and also c52, which sits after the relat and smooths the full supply voltage, it has a hard life and I suspect the 63v part that is fitted has not lasted.

  • Anonymous Sep 08, 2008

    Same issue with the KEF PSW2000. More info & circuit diagram/service manual here:



7 Answers



re: It's a problem in the grounding of the unit all you need is receptacle adapter that takes away the ground plug on the power cable.

If it is an 'earth' ground loop problem then this would likely solve the issue but it's unsafe as the S8 needs its earth connection to be safe in case of electrical fault. It's not 'double insulated' construction.

And if it makes the noise / hum without being connected to any other piece of kit then it's not an 'earthing' problem anyway.

I have a faulty S8 which just makes either no sound or a big hum just on its own.

Posted on Nov 01, 2008



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The relay chatter is because its getting AC from the board. I took the relay off the board and tested it with 24VDC it works fine - checking with a multimeter it seems the relay is getting about 20vDC and at the same time 8V AC ! Normally my multimeter wont read AC if its DC and vice versa - very strange! But the question is what is causing the circuit to get AC?

Posted on Mar 07, 2008

  • Dan Lodge
    Dan Lodge Jan 04, 2018

    I have the same issue. How did you fix it?

  • Dan Lodge
    Dan Lodge Jan 04, 2018

    I have the same issue. How did you fix it?




It's a problem in the grounding of the unit all you need is receptacle adapter that takes away the ground plug on the power cable.

Posted on Feb 24, 2008


I too found my subwoofer humming after about 3 years... weird thing is i found the solution to my problem... i turned on my sub, it hummed, i disconect the cable from my tv, IT STOPS!!! i am going to radioshack tomarrow to pick up a device that connects my cable to my tv to stop the interference

Posted on Nov 13, 2007


If the sound source is on a different circuit or plug it produces some kind of a loop (dont know the technical name) Go to radio shack and get a ground loop disrupter that goes on the audio cables right before the speaker and it eliminates that hum.

Posted on Oct 05, 2007


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When you say check the caps what do you mean? I also have a Celestion S8 Sub that is about 3 years old and has just started doing this exact same thing. Celestion say they'll fix it for about £50. Could you be a bit more specific for those of us that don't know much about electronics :o)

Posted on Nov 02, 2006


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I would check the electroltyc caps in the power supply They general are in the first part of the power supply and there will be two of them . What they do is filter out transformer hum and help stabalize the circuit. I am not saying this is absolutely the problem but the capcitors are relatively inexpensive, Easy to change. And have a habit of going bad after a couple of years in use.

Posted on Sep 03, 2006

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