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emptystring
05-01-2008, 09:38 PM
Hi all,

I've had a pair of L-100 Century for about a month now - love the sound. I'm driving them with a Lyngdorf 2175 and some Analysis Plus speaker cables.

Yesterday when I was playing music, I heard some crackling sound coming from the left speaker during a song - maybe 2-3 seconds in length, happened twice within the same song. And then gradually there's less and less sonic information coming out from the left channel. I put my ears close to the left channel - there is still sound coming out from tweeter/mid/bass, but very weak.

I tried playing music again the next morning - it started off ok, but eventually I lost most of the left channel again. Then I swapped the speakers physically, and the same thing happened to the right channel (so my amp is not the problem here). I've also tried listening to music using a different pair of speakers (Epos M5), and they were just fine.

I am really not familiar with vintage JBLs at all - these L100s were given to me by someone else, and I believe nothing was altered/modded previously.

I haven't played with the tone adjustments on the front panel - someone suggested doing that and see if there is any improvement.

Some also suggested that the crossover burned out due to old age - is that situation likely? If so, is it possible to get it fixed?

What's the best thing to do at the moment?

Thanks in advance =)

SMKSoundPro
05-01-2008, 10:23 PM
Welcome to the forum.

Go ahead and turn the l-pad knobs back and forth to "scrub" the internal contacts.

The crossover circuit is very simple with basically consists of a couple of caps and l-pads. The l-pads are rarely turned, and there tends to become a worn or burned spot in the internal windings. A very common problem on speakers with a few miles on them.

If necessary, replacement l-pads are very easy to install. Use 8 ohm, 15 watt models. I have done a bunch of those in my life as a JBL recone service shop employee.

Good luck!

Scott.

emptystring
05-02-2008, 12:07 AM
Welcome to the forum.

Go ahead and turn the l-pad knobs back and forth to "scrub" the internal contacts.

The crossover circuit is very simple with basically consists of a couple of caps and l-pads. The l-pads are rarely turned, and there tends to become a worn or burned spot in the internal windings. A very common problem on speakers with a few miles on them.

If necessary, replacement l-pads are very easy to install. Use 8 ohm, 15 watt models. I have done a bunch of those in my life as a JBL recone service shop employee.

Good luck!

Scott.

Scott -

Thanks for the suggestion, I will try that when I get home.

Fred Sanford
05-02-2008, 05:56 AM
The speaker terminals on the back panel are also a common issue, with corrosion setting in & causing loss of signal. There are easy replacements available through Parts Express or similar, take a look & see if you find any chalky buildup on the terminals or between them & the wiring inside.

je