JBL horn problem.....help!!

[tonynorie]

I found out that one of my JBL 2412H-1 horns wasn't working so I ordered and just now received a new diaphragn for it.

 

I had read on line that I should take a folded piece of tape and run it through the slit in the magnet where the voice coil sits, to clean out any debris. I did that and to my surprise I pulled up a liquid.....it's coffee colored and not viscous at all (about like water). No odor either.

 

What gives?!? Is this some sort of medium wherein the coil rests, or is it water intrusion, or did something in the magnet assembly go bad and started leaking?

 

Your advice will be very much appreciated! Thank you.

[dboomer]

Ferrofluid ... be careful, it's toxic. It's basically magnetic oil that damps and helps with heat transfer. It will need to be replaced and should come in the diaphragm kit.

[tonynorie]

 

Ferrofluid ... be careful, it's toxic. It's basically magnetic oil that damps and helps with heat transfer. It will need to be replaced and should come in the diaphragm kit.

 

 

Thanks DBoomer.......none came with the new diaphragm. But at least now I know that it's not rusty water or something. I appreciate your response.

 

Tony

[tonynorie]

Well I reassembled the driver with the new diaphragm and instead of getting a good sound, the output is barely audible and veiled. So I have to assume that the driver is bad. But I would benefit from more input from some of you pros before laying out 90 bucks for a replacement driver.

 

Isn't it rare for a driver to go bad?

 

I did notice that there was a little bit of the brown residue on the original voice coil....without knowing for sure it reinforces my assertion that the driver may be bad.

 

By the way, moved the horn from my matching JBL and it sounds fine so that tells me that the crossover is ok.

 

Thanks!

[dboomer]

Yes .. it's rare for the housing to fail. Sometimes they can take enough physical abuse though to un-center the pole piece. Does it look centered?

 

There could be junk in the gap that didn't get cleaned out.

 

You might not have the new diaphragm centered and torqued down evenly.

 

Diaphragm was damaged during install (did you measure the DC resistance of the new unit and compare it to the other driver.)

 

As far as mystery fluid in the gap. If it were other than ferrofluid it would all run out when you turn the driver upside down and rinse out with a solvent. Even thick motor oil would run out after a little time. Ferrofluid stays because it is magnetic.