JBL SoundFactor SF12M Loudspeaker Repair

Sal is a busy DJ who had to use his backup system after one of his JBL speaker cabinets quit. Can the Unbrokenstring Crew help get him back on the air?

This loudspeaker has been a reliable performer but had lost its high-end, then quit entirely.

So we found this inductor inside the cabinet, probably part of the crossover.  This is the ‘quit entirely’ issue.

The grille and loudspeakers need to come out to get access to everything.

This horn driver is Made In The USA!

This pic documents the wiring polarity.  One yellow wire is solid and the other yellow wire has a black stripe.

All we are measuring across the horn terminals is the crossover impedance.  This is the ‘lost its high end” problem.

This speaker is also Made In USA!

This is a pic to document the loudspeaker wiring.  One of the green wires has a stripe.

This loudspeaker seems to be OK.  No dragging or other issues were noted.

The loudspeaker wiring was bundled up to make it more compact…

so that we could remove the crossover network and repair the missing inductor issue.  This is a simple soldering repair and has been covered elsewhere in the blog.

The date of manufacture of this assembly is stamped inside the unit on the bottom of the cabinet.

Some of these horn drivers are repairable by the end user.  Let’s see what’s involved with a repair.

The threaded horn adapter comes off when four screws are removed.

The voice coil can be removed from the magnet as shown.  This voice coil assembly is widely available from many Internet vendors, Amazon, and eBay.  This is a repair that you can do yourself if you are handy with hand tools.

I searched for this JBL assembly number and found the whole assembly on sale for about the same price as the voice coil.  And, it comes with a warranty!

This horn driver has a higher power rating than the original OEM part.  These are made in Brazil now.

Oh, and did I mention that it came with a warranty?

This dust cap keeps junk out of the interior diaphragm of the horn driver.

The new driver even looks cool.  Too bad it’s hidden inside the loudspeaker cabinet.

The assembly fits in the loudspeaker without modification and is compatible with the existing wiring harness.  The thread pattern is compatible with the horn lens.  It just screws on by hand without tools.  What’s not to like?


Another happy customer!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE