LE85 Problem...Help Wanted.

[Mike Caldwell]

Removing the back caps is easy, removing the four screws around the edges will allow the cap to come off, sometimes they may be stuck and will take a slight tap with the handle of screwdriver to crack loose.
The cap will be loose but still attached to the diaphragm with the connection wires.
You will need to disconnect the wire from the diaphragm terminals, here's where you need to be careful, loosen the screws enough to remove the wire terminals.
Most likely your going to find the foam has turned to sticky mush, hopefully pieces of it have not fallen of and got stuck all over the diaphragm. You can order new foams from JBL parts, there actually called "dampener pads" the part number is 61286. With some good open cell foam you could make your own and glue them in.

While your in the driver it would not hurt to remove the diaphragm and clean the voice coil gap in the drivers top plate. This is were you really need to be careful, after removing the three screws holding the diaphragm
the diaphragm should lift off the driver, there are two centering pins in the driver that stick up about an 1/8 of an inch that fit into holes on the diaphragm to keep it centered, sometimes the diaphragm will be stuck on those pins and you will need to work the diaphragm off the pins by starting a thin screwdriver or even a knife blade around the edges of the diaphragm.

Clean the gap out by running a piece of heavy tape around the gaps inside and outside edge, blowing out with compressed air and then repeat again. Look in the gap with a bright light or outside in the sun for any bits of dirt.

Carefully reinstall the diaphragm over the pins and start the screws back in. Normally when reinstalling a diaphragm you will run a test tone into the diaphragm to listen for buzzing and overtones. Something around 400 hz will work at lower volume level yet easy to hear. Slightly shifting the diaphragm or even the pattern that you snug the screws back down can make a difference getting rid of any buzz or overtone.
You will have to get creative in connecting your amp the diaphragm for the tone test. You can download
sweep tone generator apps from many different places

Do not use a screwdriver that has removable tips!!

[Alobar]

Thanks Mike, you have been very helpful. I'm still looking into other components of my system but after reading this thread it kind of clicked that my very solid built speakers are getting old right along with me. I hope it isn't the diaphragms gone bad, hearing how difficult they are to find. What I am hearing seems to be emitting from both speakers whatever the source may be. Maybe this winter I will open them up as after all this time the foam surly has deteriorated to toast crumbs, just like those beautiful foam grills did about 15 years ago!

[Mike Caldwell]

Thanks Mike, you have been very helpful. I'm still looking into other components of my system but after reading this thread it kind of clicked that my very solid built speakers are getting old right along with me. I hope it isn't the diaphragms gone bad, hearing how difficult they are to find. What I am hearing seems to be emitting from both speakers whatever the source may be. Maybe this winter I will open them up as after all this time the foam surly has deteriorated to toast crumbs, just like those beautiful foam grills did about 15 years ago!

Just for the sake of testing do you have another speaker you could swap out to do an A B test with. Do you hear what your hearing at all volume levels. Maybe try listening with headphones.

[Alobar]

Just for the sake of testing do you have another speaker you could swap out to do an A B test with. Do you hear what your hearing at all volume levels. Maybe try listening with headphones.

I currently have only the L200's. What I have heard I have not noticed with headphones specifically but I rarely use them other than for travel. That is a good idea and when I find a tract that seems to be exhibiting this distortion I am going to have a good listen with the phones.

The deal with whatever I have been hearing does not seem to be volume specific and that it sounds like the same one specific frequency somewhere in the middle of the LE 85's domain, however it seems to occur only during more complex passages such as several voices singing together or sometimes keyboard will do it. It sounds scattered like the first digital online radio stations sounded with digital artifacts plainly heard at 64kbps .

I tried something last night and am evaluating now. I pulled every interconnect, speaker wire and even 120v plugs and cleaned everything with deoxit. So far I haven't had a lot of critical listening time but am cautiously optimistic. It does appear to be a good improvement!

So wanted to ask you about the open cell foam. I want to have it on hand before I start. What is a good density and how thick does it need to be? This is for dampening as I understand it so seems critical to get it close to original. I am assuming that it adheres to the cap and not the diaphragm.
Thanks again for your help..

[Mike Caldwell]

Try sweeping the system with sine wave tone, single frequency tone can be very useful in finding buzzes and distortion.

Connect the headphones directly to a speaker lead ( at a lower volume) put the negative on the longer
sleeve and the positive on the tip, the tip is the left headphone and the small middle ring is the right headphone.

The foam is about 5/8 thick and goes on the drivers back cap. not sure what the actual foam weight/density is.

[Alobar]

Try sweeping the system with sine wave tone, single frequency tone can be very useful in finding buzzes and distortion.

Connect the headphones directly to a speaker lead ( at a lower volume) put the negative on the longer
sleeve and the positive on the tip, the tip is the left headphone and the small middle ring is the right headphone.

The foam is about 5/8 thick and goes on the drivers back cap. not sure what the actual foam weight/density is.

The reason for this is to bypass the headphone amp and run directly off the same circuit as the L200's are? Sounds like a good idea to eliminate another potential distortion source.

As I am writing this I was listening to some keyboard and I thought I could still hear the scratchy sound so probably the wire terminal cleaning was wishful thinking.

Use the sine wave to locate the problem frequency? I am guessing it is obtained over the net.

I am going to be alone over Thanksgiving for 10 days so think that will be a good time to tackle this without distractions... Seems like this is a good thing to be doing regardless..
Thanks!