Question about Sunfire Audio Players & Recorders
My Sunfire True Subwoofer Signature Mk II is starting to behave a bit strange. After the subwoofer has been playing relatively loud a humming sound sometimes remains and won't go away. If I remove the signal cable it goes away, and returns when I reconnect it.
If I turn the volume up and down the humming sound changes in volume, and sometimes when the volume is close to max a thumping sound is heard and the humming stops.
If I unplug the power and plug it in again the humming disappears and doesn't come back until I play loudly with the subwoofer again.
Could you please advise? I have tried changing the subwoofer signal cable without any effect, and I have tried removing all other cables from my reciever, also without any effect.
I bought the subwoofer used about half a year ago, and I think it's about 7 years old in total and during the time I've owned it, it has worked perfectly until for a few days ago when this started happening.
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
Posted on Jan 07, 2010
Testimonial: "Thank you for your explanation of the possible causes for this error. I will investigate with the methods you suggested! :-)"
I'm experiencing same issue with my Sunfire True Sub wondering if Henrik Larsson found out the fix?
Posted on Aug 19, 2015
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Posted on Jan 02, 2017
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