JBL TL260 midrange problem

[Sabaselfsit]

Maybe this thread should be in "Technical", but that look more like an information section rather than a place for a technical question. :rolleyes:

Anyway, bought a set of mint looking JBL TL260 limited edition (60th anniversary) speakers. The only problem is that the midrange speaker in one of them is not sounding like it should. Can feel no vibration from it when holding a finger on the membrane, even though it has sound coming from it, but very little. On the other cabinet the midrange membrane vibrate well and sound good.

So the first thing I did was changing the midrange speakers over from one cabinet to the other. The result is that "the bad speaker" comes to life like normal in the other cabinet. So the speaker itself is no the problem.
http://bildr.no/image/VTdWVnox.jpeg
http://bildr.no/image/Qm13Tmda.jpeg

My thoughts now is that the problem is the crossover. The soldering looks good on it, so I am thinking a bad capacitor is to blame. The yellow and yellow/black cable is to the midrange. There is a 100v 14uF capacitor in connection to it there on the board.
http://bildr.no/image/U0J3OGRJ.jpeg
http://bildr.no/image/SUdUNDZE.jpeg

My crappy multimeter can't measure capacitance, but if it could I guess I will need to desolder the cap to get it out of the circuit to check if it is good or not? These are JBL's own caps - called "Sounder", but I guess any correct spec hifi grade cap would do as a replacement? Or would it be better to put a quality Nichicon or Elna cap in there?

[struth]

by the bad speaker, I take it you mean the bad driver? Yes you will need to desolder the caps to check. Good quality replacements are best. also check the wiring is same on both.

[walpurgis]

I'm betting it's a bad joint of one kind or another. I see there are crimped spades in use, horrid things. They can be problematic. Personally, I'd replace them all with solder on types. Some folks may even remove them altogether and solder all joints. Can you not check continuity with the meter? If it is a bad joint/spade, you should find it.

[Sabaselfsit]

by the bad speaker, I take it you mean the bad driver? Yes you will need to desolder the caps to check. Good quality replacements are best. also check the wiring is same on both.

Yes, bad driver I meant there.

Ok, will take the crossover to a mate and check things out with a meter. Thanks.

[Sabaselfsit]

I'm betting it's a bad joint of one kind or another. I see there are crimped spades in use, horrid things. They can be problematic. Personally, I'd replace them all with solder on types. Some folks may even remove them altogether and solder all joints. Can you not check continuity with the meter? If it is a bad joint/spade, you should find it.

Ok, thanks.

[fatmarley]

Can you not play some music or sound through the speaker and just wiggle the connections to the crossover board and driver? If that doesn't work try wiggling the components on the crossover board.

[Sabaselfsit]

Had the crossover checked. Nothing wrong with it. So I changed the crossovers over between cabinets. It didn't fix anything. But confirmed the crossover is ok.

This led me thinking "walpurgis" was correct in his answer above; a bad spade. Put on new spades both for crossover and driver end= SAME!

I changed the entire cable for the midrange= SAME! At this point I was so shocked that I AGAIN changed the midrange drivers over= SAME!

This is maybe the strangest thing I have ever seen/heard. No matter what crossover, cables, spades or driver I put inside the right cabinet, it vibrates less than the midrange in the left cabinet.

I think I'll just get :drunk:

[walpurgis]

Presumably the open back midrange driver is in its own inner enclosure. Is there anything loose inside? Another possibilty and quite a common one is a wire or damping material touching the back of the cone.

[Macca]

If it isn't the speaker is it anything upstream? Have you tried swapping the speaker cables around to check? I've been there before, chasing the fault in one piece of equipment when the problem was elsewhere. Weeks of grief.

[agk]

What Marco said.

[struth]

Any possibility that the polarity of wiring into the banana's is wrong? or on the speaker line.. other possibles is a bad connection or banana socket, or if bi wireble the biwire link

[Sabaselfsit]

Presumably the open back midrange driver is in its own inner enclosure. Is there anything loose inside? Another possibilty and quite a common one is a wire or damping material touching the back of the cone.

In it's own enclosure. The cables don't touch, and the damping material don't touch. I was also thinking about this, so tested it not installed, just the driver on a chair playing music.

The speakers sound amazing. So no emergency really. But very annoying why one driver behave different than the other identical driver. Even tried playing directly from dac and into one power amp to eliminate that the fault was not in my system. Changed the speaker terminals by connecting the left speaker on the right and vice versa= SAME.

[walpurgis]

In that case, get the capacitors checked again and double check joints. There has to be a cause.

[fatmarley]

If it's an intermittent fault (probably is because you're getting some sound), swapping stuff over could have temporarily fixed the problem (that's why I suggested wiggling wires, crossover components etc).

I found a dodgy transistor once by tapping all the components with a pencil whilst music was playing. The bad one made a 'pop' sound when it was tapped.

[Sabaselfsit]

In that case, get the capacitors checked again and double check joints. There has to be a cause.

I agree. Just need to find motivation.


If it's an intermittent fault (probably is because you're getting some sound), swapping stuff over could have temporarily fixed the problem (that's why I suggested wiggling wires, crossover components etc).

I found a dodgy transistor once by tapping all the components with a pencil whilst music was playing. The bad one made a 'pop' sound when it was tapped.

Yes, that is next step now. I will take out all 5 drivers and line them up on the table together with crossover. Cable it all up with temporary cables and see where it brings me. Possible the right cabinet is cursed, so hooking up outside might break the spell.

[Macca]

Cabinet cursing. I've dealt with that before. First you need to catch a leprechaun. Dig a hole, fill it with Lucky Charms and cover it over with branches and leaves. Come back to me when you have the little fellar and I'll tell you the next step.

[Jimboj]

Hi.

I know this thread is years old, but I have the exact same problem with my JBL TL20.
Midrange driver is practically non existent on Left speaker and slightly more than nothing on the right.

Did you ever manage to sort the problem you had?

Jimbobj