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Author Topic: Speaker driver problem (JBL)  (Read 17523 times)

Curtis H List (Too Tall)

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Re: Speaker driver problem (JBL)
« Reply #30 on: May 09, 2013, 10:02:00 PM »

HOLY GUACAMOLE...

I will be VERY surprised if this failure is in the crossover.  I just got the crossover module in yesterday.  This thing is massive.  It's on a circuit board that is about 12" square.  The resistors and other parts on it can be measured in inches.  The solder traces are pretty doggone thick too.  This thing also weighs a lot - 2-3 pounds, at least.  I've never in my life seen an internal crossover module as beefy as this thing.  They definitely made these things to last.

Now to rent a lift and plan for the repairs...

I am not insisting that you have crossover problem. At this point I am just saying what it would look like if you did.
On the  compression driver first thing to look at is the DC resistance of the driver. If there is a driver problem it should show up there first. Even better measure the impedance, if you have or can get the right gear from someone.
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Jeff Foster

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Re: Speaker driver problem (JBL)
« Reply #31 on: May 23, 2013, 10:13:11 PM »

For anyone interested, it was the HF driver.  The crossover was fine.  We completed the repairs today.  The actual repair only took about 20 minutes.  Taking apart the proscenium and putting it back together (along with other maintenance tasks) took a few hours longer.  It's been a long day.

On the bright side, we did rotate the HF horns on the two center speakers in the exploded array from 60x40 to now 40x60.  The downward sound now extends a couple rows farther forward and negates the need for any front fills.  It also helps to minimize coverage overlap between cabinets which has caused the whole auditorium to sound like a seamless speaker system when moving from side to side.  Of course, it didn't sound bad before, but there was a little noticeable comb filtering in a couple of spots previously.
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Jeff Foster
Freelance system designer/installer

Ed Walters

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Re: Speaker driver problem (JBL)
« Reply #32 on: May 25, 2013, 09:39:22 PM »

For anyone interested, it was the HF driver.  The crossover was fine.

Just for extra weirdness:  I had another 2431 cross my bench yesterday.  Didn't need the new diaphragm I already bought....glue failure/shifted magnet.  New driver time...

Kind of surprising.  There's two glue joints. One is throat/phase plug/pole piece to magnet, the other is this ring that forms the outside of the gap that the diaphragm and thus back cover screw to.. The light side, mass-wise. That's the one that broke. And man o man is that one strong magnet....getting that little ring off there took tools and much cussing, even though it was only held down by the magnetic field..

So yet another stupid failure mode on what otherwise ought to be a decent driver....

Ed Walters
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Re: Speaker driver problem (JBL)
« Reply #32 on: May 25, 2013, 09:39:22 PM »


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