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johnhb
06-29-2003, 10:52 AM
Okay, now I have a problem with the 2440 in my subwoofer. Same rattle as with 2450. Does anyone know if these 18 inch woofers have the mass controlling ring in them? I had a problem like this with my 136As in L-300s a while ago. I had to remove the dust cap and have the ring re glued. The well known speaker repair shop in So Cal recommended leaving it out. They said they tend to come loose and may bottom out on the pole piece. I left it in and have had no problem.

Thanks

4313B
06-29-2003, 11:02 AM
Read the model numbers off your drivers and repost your question.
I'll post a list of JBL transducers that used mass rings later today.

johnhb
06-29-2003, 11:46 AM
The worst one is a 2240G basket I had reconed with a 2245H cone. I need to remove the other but I believe it is a 2240H?

4313B
06-29-2003, 01:36 PM
"The well known speaker repair shop in So Cal recommended leaving it out. They said they tend to come loose and may bottom out on the pole piece."

You know, the only way I know how to respond to such crap anymore is











Anyway, neither the 2240 nor the 2245 used a MCR.

johnhb
06-29-2003, 01:58 PM
Giskard. You are the man! thanks. But now I have to look elsewhere to find my rattle.

4313B
06-29-2003, 02:10 PM
Check the leads from the terminals to the voice voil and make sure they aren't rattling against the spider or back of cone.

GordonW
06-29-2003, 04:06 PM
Originally posted by Giskard
Check the leads from the terminals to the voice voil and make sure they aren't rattling against the spider or back of cone.

... or intermittently touching EACH OTHER. I've had to remedy that on several JBL drivers, when the metal strips that connect the braided wires to the terminals, got bent too far toward each other, to where the wires could come in contact.

If they're touching, itwill somtimes make a "popping" or "crackling" sound, which can sound just like a loose component in the moving assembly! Not to mention possibly driving the amp NUTS...


Regards,
Gordon.

boputnam
06-29-2003, 06:20 PM
You may be well beyond what I'm suggesting here, but have you removed each transducer and bench tested for same-same? You should sweep each with the LF spectrum - a handy CD tool is the "Bass Zone Test CD" from http://www.stryke.com/

(no affiliation nor monetary relation - only satisfied user! :D )

but keep the gain down while doing so.

I today struggled through - and whipped - a nagging buzz in my RH 4345 cabinet. Swept it and found it restricted to 71Hz to 112Hz, but could not source it for the life of me. Bench tested each the 2245H and 2122H - and nothing. So, clearly it was something cabinet related. And at those frequencies, there's a WHOLE lot o' shakin' going on! I suspected it might be bracing or bracket related, and found finally it related to the rear bracket for the 2421B horn - one of the screws had gone missing. Yea!

Now, if I can only get this ringing outa my ears... :D :D :D