LX5 - Un-potting

[Caledon Ken]

I would like to investigate un-potting my LX5's. I've done some research on the internet and was hoping someone in these forums could either tell me what the material is that was used to pot them or what I can do to un-pot them. ( I also searched these forums and did not find an answer.) It has also been suggested that I by-pass the LX5's.

About twenty years ago I replaced one of the LX5's and as part of the deal I had to hand in my old one. I assume it was going to be rebuilt so somehow these are being un-potted in a nondestructive way. Unfortunately the old shop is gone so I can't ask them what they do with the old ones.

If it is epoxy I've read that acetone might work on certain epoxy variants. Failing that you are into some very nasty chemicals like Nitric Acid or MEK. I imagine all theses chemical would strip the paint and other markings off the case which is something I want to avoid.

If is tar I assume something like varsol would eventually release the contents. Bee's wax would be ideal, warm water on the stove was suggested in these forums.

Has anyone un-potted an LX5 or other vintage JBL gear and could you share some detail on the steps you took?

[hjames]

Although its probably been 4 or 5 years since I did this, here are the details:
The crossover in my 4320 was potted in beeswax. It was not an LX5 tho.
Basically I had to remove the assembly from the cabinet and drill out the rivets,
then I put the metal can in a double boiler with the can top well above the waterline.
I brought it up to temp until the wax melted and turned clear, then I poured the wax into a small can
(from some tomato paste, I think) and saved it for later reuse.

I eventually moved the drivers into a pair of L200 cabinets and scratch built new crossovers
based on a design Mr "4313B" shared with us here.
Those speakers have been tweaked even further now - but that's another thread ...



I would like to investigate un-potting my LX5's. I've done some research on the internet and was hoping someone in these forums could either tell me what the material is that was used to pot them or what I can do to un-pot them. ( I also searched these forums and did not find an answer.) It has also been suggested that I by-pass the LX5's.

About twenty years ago I replaced one of the LX5's and as part of the deal I had to hand in my old one. I assume it was going to be rebuilt so somehow these are being un-potted in a nondestructive way. Unfortunately the old shop is gone so I can't ask them what they do with the old ones.

If it is epoxy I've read that acetone might work on certain epoxy variants. Failing that you are into some very nasty chemicals like Nitric Acid or MEK. I imagine all theses chemical would strip the paint and other markings off the case which is something I want to avoid.

If is tar I assume something like varsol would eventually release the contents. Bee's wax would be ideal, warm water on the stove was suggested in these forums.

Has anyone un-potted an LX5 or other vintage JBL gear and could you share some detail on the steps you took?

[Caledon Ken]

Thanks for the response. Now people will have a documented method for bee's wax. Any body tried an LX5?

[subwoof]

the old black LX5 has the same wax as the later models - heat and you're good to go.

the 13.5 ( or 16.5 ? ) cap in the HF section is the usual culprit that goes bad ( opens up ).
I have some of them in storage if you need to keep it original.

sub

[Caledon Ken]

Thank you subwoof.

Both my existing LX5's are working but I'm in the process of costing out an entire restoration, they are part of a Sovereign C60 S8R's set. Enclosures are rough, small brace for one lens is broken, "Lansalloy" cracked.

One of LX5's is original so I'm assuming, likely incorrectly, that time is not on my side and will fail, especially if I put the speakers into very regular use. One of the N7000's quit so no sound in 075 which I just noticed.

I'm thinking I should replace all the electronics in both of the LX5's and N7000's. I would like to keep them as original as possible but I'm leaning towards modern replacement electronics as I really won't be able to source everything original, at a reasonable price. I'm also reading as much as I can on suitable crossovers as some say these aren't the best. In another thread, or two, it was suggested that N7000 owners use a bypass cap on the existing caps which I plan to implement.

I'm reading, learning and asking a whack of questions.

I will definitely keep you name for future reference / parts. Thanks again for answering this thread.

[subwoof]

the cap also opens up in the N7000 HF section...

Yeah you can replace the caps ( and bypass them ) and the original performance will return BUT many other larger issues will keep these with that era's sound...it's a big stretch to have that short of a horn behave at 500hz and there isn't much you can do short of putting another horn on top and playing network games.

The most successful of the big 3 ways was the 4333 and I happen to have a pair of home-built crossovers another forum member made with high quality components sitting in a box somewhere. if interested, PM me and I can get a pic to you.

And put the original crossover back into their holes for the next owner to make that decision....:)

sub

[Caledon Ken]

Thanks. I did see the posting on the "Range Gap" between 500-1200Hz. Mr Widget had suggested different cabinets to improve sound but Johnny brought me back to earth with the work involve in creating new cabinets and that still won't address driver issues. More to investigate. Thank you for all your responses. I check out how to PM as I would like to see pic.