Wharfedale W15RS Rattle

[Rockaway]

I have a Wharfedale w15rs that I noticed has a pronounced rumble or rattle sound when handling very low frequencies. I usually listen to acoustic music at
moderate levels but today was listening to electronic "trance" music and the rattling sound suddenly became apparent. I did a rudimentary test for VC rub and ruled that out. It seems the the treated cloth surrounds make a buckling sound (think sail cloth or other waterproofed fabric) when flexed. To make matters worse, there is a pinched part in the surround which appears to be a manufacturer's defect. As the surround was glued, excess fabric pinched in that spot. This means that the surround is not a perfect half-pipe configuration and when flexed......You get the point.

Any suggestion other than re-foaming? Does anyone have experience with these drivers?

Thanks for your patience with this tedious description.

- Jason

[Cal Weldon]

Check for loose fasteners. If that's not it make yourself a stethoscope from two funnels and a tube or even a cheap one from the dollar store to locate the noise. Hopefully it's not the surround. It would be unusual if that's it. Might it be the cabinet itself?

[Rockaway]

Cal,
Thanks for the suggestion. These drivers are not currently in any baffle so I can rule out cab.resonance, loose mounts, etc... I can actually force the sound by depressing the cone or pulling to toward the front of the basket. It is very odd indeed.

-J

[Cal Weldon]

Can't say I've run into that before, Can you show us a pic or two of the surround?

[Rockaway]

Cal,
I tried to shoot a pic but the crease or fold in the rolled surround is under the lip or mounting edge of the cone. These surrounds are really quite amazing since they have outlasted the foam of that era and remain flexible where say
JBL white walls. I just got one that is a lemon apparently.

-J

[Rockaway]

I meant to say that the JBLS harden over time.....

[Rockaway]

Cal,
do you think that a decay in the surround sealant could cause the rattling sound? I tested the surround which is not 100% sealed. If so what is the consensus on sealants? I have read everything from Latex to Gasket sealer.

Thanks,

Jason

[Rockaway]

Mystery solved. I realize that no one will read this except me however in the event that someone experiences the same problem I am updating this thread. The problem, it turns out, was a loose dust cap. About one quarter of the cap had become unglued and would rattle when pushed to very low freq. A very slight buzz was also apparent after I discovered the problem. A little PVA and as good as new.