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Old Jul 29, 2009, 06:27 PM   #1
beerstine
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Intermittent Subwoofer Static

I have a Cambridge Soundworks subwoofer attached to my Mac Pro and has just been emitting intermittent static noise regardless of whether audio is being played through the system. The static only seems to affect the subwoofer and not the satellite speakers and continues even if the input volume is turned down on the unit and in OS 10.5.7.

I have moved the power adapter to different outlets and away from other power cables but that has not made a difference. I have an APC battery backup unit about a foot away from the subwoofer, but it has been in a similar position for years without the static problem that recently began.

Any suggestions?
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Old Jul 29, 2009, 11:35 PM   #2
thegoldenmackid
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For me I had a cable problem... But, that was with separate cables from the mixer to sub and speakers. Given that that speaker for you is internal....?
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Old Jul 30, 2009, 12:42 AM   #3
ChrisA
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Quote:
Originally Posted by beerstine View Post
I have a Cambridge Soundworks subwoofer attached to my Mac Pro and has just been emitting intermittent static noise regardless of whether audio is being played through the system. The static only seems to affect the subwoofer and not the satellite speakers and continues even if the input volume is turned down on the unit and in OS 10.5.7.

Seems to me the problem must be in the subwoofer itself. Also I assume you have tried wigggling all the connectors and not found anything loose
I"d still bet on a loose connection one internal to the amp that drives the subwoffer. Maybe it's a connector that is loose or it could be solder connection that was not done right.

If you could give a better description of the sound it would help a lot.. Is it for example a soft hiss over the music, a series or loud clicks. Does the music cut in and out or is the noise over the music.

The worst case it you have to replace the plate amp in the woofer. They are not all that expensive.
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Old Jul 30, 2009, 01:56 AM   #4
beerstine
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Cables were the first thing I looked at and I reseated all the connections. They feel solid, though I can't tell if there's something wrong underneath.

It's not a loud popping or thumping but sounds like static or crackling even when all system audio inputs are turned down or off, but only from the subwoofer. The tweeters make no such sound. The noise is not constant but consistently manifests itself every minute or two for a few seconds at a time
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Old Jul 30, 2009, 12:40 PM   #5
ChrisA
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Originally Posted by beerstine View Post
Cables were the first thing I looked at and I reseated all the connections. They feel solid, though I can't tell if there's something wrong underneath.

It's not a loud popping or thumping but sounds like static or crackling even when all system audio inputs are turned down or off, but only from the subwoofer. The tweeters make no such sound. The noise is not constant but consistently manifests itself every minute or two for a few seconds at a time
Whenthe music is on, does the static sound over music or does the music cut out? If we are talking about a sub-woofer "music" may be the wrong term as it only plays the very low end.

I suspect the amp in the woofer. They are repairable buy you need test equipment and some debugging skills. None of the parts cost more the a few bucks. But without the equipment and skills people simply replace the entire amp modual and associated power supply. Cambridge may have an exact replacement but a place like PartsExpress might have something you like better, maybe? Here is an example ( http://www.parts-express.com/pe/show...number=300-782 ) Google will turn up more.

Before to do that. Check for suspect internal connectors and solder joints

Last edited by ChrisA; Jul 30, 2009 at 12:46 PM.
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Old Jul 30, 2009, 03:48 PM   #6
beerstine
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May have isolated a cable problem

When sound is being pumped through it, the noise is barely noticeable and the sound never cuts out completely, it is very noticeable when the system is silent.

I have found that the volume control cable which plugs into the subwoofer might be where the problem is. It goes in solidly and isn't loose, but when it's disconnected the noise goes away. I'm going to have to see if there's a replacement part available (it's a fairly old unit).

At this point, probably cheaper to buy new rather than repair since I don't have the gear or the knowledge to do it myself.
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Old Jul 31, 2009, 01:00 AM   #7
ChrisA
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Originally Posted by beerstine View Post
When sound is being pumped through it, the noise is barely noticeable and the sound never cuts out completely, it is very noticeable when the system is silent.

I have found that the volume control cable which plugs into the subwoofer might be where the problem is. It goes in solidly and isn't loose, but when it's disconnected the noise goes away. I'm going to have to see if there's a replacement part available (it's a fairly old unit).

At this point, probably cheaper to buy new rather than repair since I don't have the gear or the knowledge to do it myself.
SO the noise is additive. That rules out half the problems. but you seem to have found the real problem.

THe wipers on the pots get gunk on them over the years. need to be cleaned with contact cleaner. Some times you can fix it but simply rotating the knobs from full to zero volume and back about 200 or 300 times. But I have one on an older guitar amp that even long shots of cleaner can't fix. The part sells for about $1.80 but I'll use a "made in USA" replacement for $7
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