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-   -   JBL 2241H subwoofer - makes buzzing noise (http://www.diyaudio.com/forums/subwoofers/223605-jbl-2241h-subwoofer-makes-buzzing-noise.html)

Jimmy154 15th November 2012 01:42 AM

JBL 2241H subwoofer - makes buzzing noise
 
I don't know if any one here is familiar with these woofers and can tell me what is the most likely cause of this buzz. The leads don't seem to be hitting anything. It starts to buzz at about 1-2 mm excursion one way. I think the sound comes from behind the dustcap, but it also kind of sounds like it's coming from the surround on the side that has the leads.

I don't want to cut out the dustcap, only to find out that the sound comes from the surround or somewhere else.

buzzforb 15th November 2012 01:44 AM

Sounds like voice coil rub.

googlyone 15th November 2012 02:05 AM

Gently but firmly push the cone in and out (push cone out from the underside near the voice coil for "out") and check for rubs.

You can be very firm in doing this, don't be shy!

Any rub is a very good indication of either voice coil damage or magnet movement.

A fail on this test would lead me to stripping the driver down.

Jimmy154 15th November 2012 03:24 AM

I did that.
The voice coil doesn't seem to rub.
It plays decent. But it has a rattling/buzzing noise.
Sounds just like leads hitting/vibrating against the cone or basket, but they are not.

m R g S r 15th November 2012 11:56 AM

Are you testing and hearing th buzzing when the driver is out of the enclosure, in free air?

Jimmy154 15th November 2012 02:16 PM

Free air definitely, but I heard it in the enclosure too, I think.
I'm not sure, if it was this particular one.

weltersys 15th November 2012 03:16 PM

Jimmy,

Check the dust cap carefully for a cracked glue line.

ajazz 15th November 2012 03:22 PM

If you have used this woofer for a long time then definately the ends of the coil has blackened and lost its adherence to the former (Kapton or Fibreglass) which creates a buzzing sound after 1 or 2 mm of cone movement i.e when it comes under the magnetic gap. If it is so then it calls for stripping down & replacing the coil.

epa 15th November 2012 04:20 PM

you also want to check for tiny tears in the spider or surround.
when you put a signal on it ,press the cone ,spider and surround at different points.
this might help to locate the problem.

Djim 15th November 2012 05:03 PM

Quote:

Originally Posted by Jimmy154 (Post 3242070)
I think the sound comes from behind the dustcap, but it also kind of sounds like it's coming from the surround on the side that has the leads.
I don't want to cut out the dustcap, only to find out that the sound comes from the surround or somewhere else.

Hi Jimmy,

The way you describe your problem, I think ajazz explanation is most likely. When you power your drivers with a too high RMS signal over a long time, your coil is going to 'glow' and turns the adhesives (used on the Voice Coil to keep it on place on the former/piston) into powder. The only way to check this is to cut off the dust cap. In case you find the evidence (usually looks like white powder), the driver will need a recone. If not, the dustcap is the easiest and cheapest to replace.


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