Apparently there is nothing obvious, but its back together again. However I
think the slight hum going away in seconds is getting worse, so I am a bit
worried,
Do they still go bang like they used to, though it has to be said none seem
warm at all. I do not really want a speaker coated in lots of gunge.

Brian

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"Adrian C" wrote in message
...
On 20/01/2010 10:12, Brian Gaff wrote:
My subwoofer picks up. Mobile phones, radar pulses, clicks and bangs on
the
mains and occasionally short wave radio.


The very short speaker wires from amp to speaker in the box appear to be
the
culprits for the higher frequencies, and the input leads the way in for
the
rest, except
The mains borne crap.

It has a three core mains lead of the iec variety, but its only been
doing
these things since it had a new bridge rectifier fitted a while back. I
am
suspicious that some capacitors may have been damaged when the bridge
went
down, but I'd have thought this would just result in hum.

The amp is built on pcbs maounted on the heatsink which effectively forms
the back of the cabinet beside the port.


I'd look closely at the supply decoupling electrolytics for the final
stage amplifier, be it an integrated module or discrete components. If
it's a module it could be possible that it's been used without much
bandwidth limiting (as per use in other applications that are full
bandwidth) relying instead on upstream low pass filtering for the function
of your subwoofer, and this is where interference is getting in.

Are any caps showing signs of bulging / dome'ing?

--
Adrian C