One of my JBL L19 speakers is acting up. Please help...

Mr.White

AK Subscriber
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Hello fellow AKers.
I have a pair of JBL L19 speakers which I bought refoamed about 5 years ago off Craig's List. These speakers have served me faithfully all this time and they suit my needs just fine. I like them.

Recently though I have noticed some distortion from one speaker. I switched them and the problem followed the speaker so it's the speaker. On some recordings and only on particular songs I hear a low level distortion. Sort of like a static. It's always the same type of distortion in the same spots on various recordings. These recordings do not exhibit this problem on other systems. So something is up with the speaker.

I realize these aren't the greatest speakers and I've gotten my money's worth. But, I do like them and I'm hoping I might be able to fix the problem with the help of some of you kind folks.

Thanks!
 
Have you tried adjusting the tweeter L-pad (labeled HIGH FREQUENCY LEVEL) while playing music through the speaker? These L-pads (and L-Pads in general) often acquire some surface corrosion on the internal winding over time. Whenever I recap a pair of vintage JBL speakers, I disassemble, clean, and reassemble the L-pads.

It is possible to clean them without disassembly by spraying some Deoxit in through the small vent holes in the cover. Alternately, for a temporary fix, just try rapidly turning the knob back and forth about 30 or 40 times each and see if that helps.

It may also be a bad cap in the crossover, or a bad driver (maybe a sagging spider on the woofer), but I'd check the L-Pads first before trying anything else.

The L19s may not be the greatest speakers, but for what they are (8" 2-ways) they are pretty darn great. They are a favorite small speaker both here and at the Lansing Heritage site. I recently finished recapping and refoaming a pair and am very impressed with the sound.
 
Have you tried adjusting the tweeter L-pad (labeled HIGH FREQUENCY LEVEL) while playing music through the speaker? These L-pads (and L-Pads in general) often acquire some surface corrosion on the internal winding over time. Whenever I recap a pair of vintage JBL speakers, I disassemble, clean, and reassemble the L-pads.

It is possible to clean them without disassembly by spraying some Deoxit in through the small vent holes in the cover. Alternately, for a temporary fix, just try rapidly turning the knob back and forth about 30 or 40 times each and see if that helps.

It may also be a bad cap in the crossover, or a bad driver (maybe a sagging spider on the woofer), but I'd check the L-Pads first before trying anything else.

The L19s may not be the greatest speakers, but for what they are (8" 2-ways) they are pretty darn great. They are a favorite small speaker both here and at the Lansing Heritage site. I recently finished recapping and refoaming a pair and am very impressed with the sound.

I removed the back panel so I could get directly behind the High Frequency Level knob. I sprayed it with contact cleaner and worked the knob back and forth 50X. The distortion is still present.
 
I removed the back panel so I could get directly behind the High Frequency Level knob. I sprayed it with contact cleaner and worked the knob back and forth 50X. The distortion is still present.

Can you tell if the distortion is coming from the woofer or the tweeter (maybe try the paper towel tube test)?

If you think it's the woofer, try removing it, rotating it by 180 degrees and reinstalling it.

If you think it's the tweeter, try swapping tweeters between your two speakers and see if that makes a difference.

Another option, since you've already got one of the crossovers out, would be to swap the crossovers between the two speakers and see if the distortion follows the crossover or the drivers.
 
Soldering would be required to swap crossovers and drivers, yes? I've heard these terms but not 100% certain exactly what parts they refer to.
 
You should be able to disconnect the tweeter without soldering. I had the same problem on these speakers and fudging with the tweeter fixed it.
 
Possible voice coil rubbing. This could be due to playing too loud and heating up the coil to the point where the varnish on the windings melts and causes interference in the gap.
 
Soldering would be required to swap crossovers and drivers, yes? I've heard these terms but not 100% certain exactly what parts they refer to.

No, the leads are not soldered to the drivers. So, you can either move the drivers (woofer and tweeter) from one cabinet to the other, one at a time, or move the crossover from the bad cabinet to the good one.

Probably the most efficient order would be:

Rotate the woofer in the bad speaker by 180 degrees and see if that makes a difference. If it fixes the problem you were getting some rubbing of the voice coil due to a sagging spider. Leave it in the new orientation.

If not, move the woofer from the good speaker to the bad one and see if that makes a difference. If it does, you have another issue with the woofer that will need attention.

If not move the tweeter from the good speaker to the bad one and see if that makes a difference. If it does, you have an issue with the tweeter that will need attention.

If you get to this point and the problem persists, it lies somewhere in the crossover.
 
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BTW, once the source of the problem has been root caused, it's well worth repairing your L19s, even if it means sourcing a replacement driver. They really are excellent sounding speakers. Maybe a bit under the radar compared to larger vintage JBLs, but they receive universally high praise from those who have heard a pair in proper working condition. I'm constantly amazed by how good my L19As sound given their modest size and driver compliment.
 
Actually that first test, flipping the woofer upside down, can be accomplished by turning the whole speaker upside down. :D If it fixes it you can then proceed to unscrew the woofer and actually rotate it so you can have the speaker right side up again.

You can also try gently pressing on the cone while it's playing (not at huge volume but enough to hear the distortion). Press with fingers on one area of the cone (say, 3 o'clock) and see if it helps, then move around. If you find a spot that makes the noise go away, then try rotating the woofer to permanently fix.

One or the other test may work and the other might not.
 
Ok, back after some rest. I have rotated the woofer 180 degrees and in 30 minutes after my receiver warms up we'll have a listen.

I also tried removing the tweeter while I had the woofer out. I am not sure how to do this. I removed the screws but I could not get the tweeter to come out. Not by prying with a thin knife from the top or pushing out from underneath. How exactly does one safely remove the tweeter?

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Ok. The rotation of the woofer did not fix the problem. Now I have switched the woofers. The wife is yelling, something about it being 3:00am so I'll wait until a more suitable hour and see what we have. I'll report back later.
 
Here's what I did to remove the tweeters on my 4311's. Push a utility blade under the edge to protect the wood and pry them up with a small flat screwdriver slowly. Mine had runny woofer goop on it and the double sided sticky backing, was heck to remove. I think there's lots of ways suggested here, maybe heat ?

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Well I switched the woofers, cleaning all contacts in the process. The problem seems to be gone. I've listened to two CDs where this noise appeared on certain tracks and no noise. This noise was more noticeable when the receiver was at a low volume with the loudness switch on. I tested the tracks both ways and the noise is gone.

If it returns I'll ask more questions. Thank you everyone for your help and suggestions.
 
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