B&W ASW-CM Subwoofer Bass Unit Rattle

[bnieman]

Hello all,

My ASW-CM has developed a rattle in the bass unit. I took apart the sub to isolate the problem and unfortunately it's not a screw tighten fix. The bass unit rattles even when held outside of the cabinet.

Here is what the rattle sounds like: http://bryan.frommfamily.com/bw-sub-rattle.m4a



The rattle only occurs once you have sufficient bass at a certain threshold. The threshold is pretty low, when sending a line level signal to the sub it will start to rattle around 1/4 volume.

Does anyone have any ideas? Or should I bring it in to my dealer for repair? The replacement cost for the bass unit on B&W's service site is $423.54 but they have zero in stock.

Service Manual: http://bwgroup-support.com/downloads...SW%20CM-TM.pdf

Cheers,
Bryan

[windshear]

Check your pigtails. These are the flexible wire leads going from the terminals to the voicecoil. Firstly they should have enough flex in them, secondly check for no dry joints on the contacts and thirdly, check if the pigtail is glued to the spider edge and may have worked loose, causing a rattle. I have encountered all 3 these problems recently on a pair of 802D's.

[bnieman]

Thank you for your reply windshear.

Are the pigtail leads the leads in the picture going from the cabinet to the bass unit? If so I made sure those were secure and when I played music while holding the bass unit in my hands I could tell the rattle was not coming from the leads.

I did not see any other leads and I do not see any in the service manual either (page 2 http://bwgroup-support.com/downloads...W%20CM-TM.pdf).

Best regards,
Bryan

[windshear]

No the pigtails are the leads that go from the connector on the actual driver into the inside over the spider and then the voicecoil.

The other possibility iis that the spider has collapsed. If that is the case then changing the orientation of the driver would either reduce or accentuate the effect of the voice coil rubbing.

[bnieman]

I did try holding the driver in different orientations and it did not affect the rattle (it neither reduced or accentuated it).

Does checking the pigtails require dissembling the bass unit itself? If so that is a bit out of my comfort zone as it would appear it takes a bit more than the hex screwdriver I used to open up the cabinet and pull out the bass unit.

Again thanks for the information, I think I will take the sub into my dealer tomorrow (they are closed Mondays).

Cheers,
Bryan