View Full Version : Jbl 077

02-13-2004, 09:58 PM
I have a pair of JBL L300. They were given to me by a friend and I never used them until yesterday. I had the woofers re-foamed and hooked them up to play them.

The tweeter does not seem to work on one of the speakers. The weird thing is when I played with the brilliance (I think it was the brilliance control) the mid-range had some static and cut in & out for a second, but then worked fine. I turned the control several times until I didn't hear anymore static. However the tweeter on the same speaker doesn't seem to work.

Could it be the crossover?

Stupid question, but if it's the tweeter, can it be rebuilt?


02-13-2004, 10:11 PM
Check it one step at a time. Since the midrange level control is iffy it is likely the problem with the tweeter is also the level control. Fool with it. Turn it back and forth several times. I don't know how that crossover is mounted, but if it can be removed just by taking out the screws, drive the tweeter directly at VERY LOW POWER with your bass tone control turned way down to see if it works. Be careful. Both the level controls and the tweeter voice coil/diaphragm can be replaced.


Mr. Widget
02-14-2004, 12:49 AM
Originally posted by Scott1215

Stupid question, but if it's the tweeter, can it be rebuilt?

If it is the tweeter they cost just over $100 each to re-diaphragm. Like David said I would bet the problem lies in the L-pads (tweeter and mid controls). They tend to get dirty over time and will get noisy and also can cut out completely. It will undoubtedly improve the sound of your speakers if you shoot some contact cleaner into the little vents on the back of the L-pads then rotate the L-pads fully several times. If they continue to be scratchy sounding they must be replaced. They are about $25 each from JBL or between $5 and $10 from other suppliers.

If this doesn't solve your problem, try switching the tweeter from speaker to speaker. If both tweeters work but only on one side you need to look at the wiring, L-pad, and crossover. Obviously if when you try the "dead" tweeter in the other speaker if it is still dead you need to take it or ship it to a qualified JBL repair center.

Good Luck!

02-14-2004, 04:24 AM
Thank you for the help.

02-14-2004, 08:33 PM
Ok it is the crossover. The two capacitors (1.5uf 200v) and I think
they are two reisistors (20 Ohm 10F) are broken. The wire leads broke very close and can't be soldered back. Probably caused by moving the speakers.

Any recommendations on replacements?

Can I just order them from a place like Parts Express?

Thanks Again.

02-14-2004, 08:50 PM
You could get Audiocaps from Parts Express
Sonicaps from http://www.soniccraft.com/parts/capacitors.htm
Hovland Musicaps from http://www.madisound.com/
Multicaps, Relcaps or Dynamicaps from http://www.percyaudio.com/

02-14-2004, 09:21 PM
Great. Thanks for the links.

Mr. Widget
02-14-2004, 11:52 PM
You should change the caps in both crossovers as the new ones will not sound exactly like the older mylar caps.