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Thread: Questions on the resurrection of the LE175/1271-1290

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    Senior Member BMWCCA's Avatar
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    Questions on the resurrection of the LE175/1271-1290

    A fine gentleman over on AK had been storing what is basically the components of the 001 load. The 130As were in need of re-cone, the crossovers looked awful, and the LE175/1217-1290s looked like they could be salvageable. He ohm'd them at normal range so I made an offer just for those. Then he threw in the crossovers and paid for shipping himself! A fine gesture. Later he told me he did not have indoor storage for these so they'd been wrapped in plastic and stored "outside", whatever that meant. I've had two 030 systems, one of which was my Dad's and is now over 65-years old. Years (decades) ago I bought two slightly mis-matched (one plywood the other particle board) empty C35s and they've been stored since arriving. Over 50-years ago I acquired one LE175DLH and an N1200 hoping to add it to the 030 with some N7000s but then got crazy and now own over a dozen other JBLs. I also acquired two Crown crossovers VTX---2s from a member here who is no longer with us. I have over a dozen Crown amps including several D45 and D75As and had always toyed with the idea of a tri-amped 3-way 030-based FrankenJBL with this stuff. And now I have two LE175 to play with.

    One of these had a sticker and what appeared to be a repair tag on it and the wax seals were gone. So that's where I've started. I don't understand what's the big deal on untouched red-wax seals and when I opened this one and saw a badly deteriorated foam damper just like more modern JBL tweeters, I'm now wondering why that's not a critical update to these old components just like any titanium driver with the foam piece? Of course that violates the iconic red-wax seal!

    That being said, I'm wondering if the repair was a new diaphragm and if anyone can tell me if this looks like an original JBL part?





    Here's what the foam looked like:



    And here's my replacement I hand-cut from air-filter-stock I bought for my few amps that have filters on them (Crown Studio Reference-II and some Carver pro amp):

    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Senior Member BMWCCA's Avatar
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    These are the "for-sale" photos from the previous owner:







    The LE175s are consecutive serial numbers and the horn/lens are 17-digits apart.

    He also had what's left of a JBL Energizer:



    And, if anyone ever wondered what the inside of a potato-masher lens looked like on a 1217-1290, there are lots of felt gaskets and other stuff separating the layers. Nicely done in typical JBL style:




    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Senior Member 1audiohack's Avatar
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    Hi;

    It looks OE to me. Also I have seen the small deformations in the tangental surrounds visible in your picture at just after 2 O'clock on other known OEM JBL 1” diaphragms.

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

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    Quote Originally Posted by 1audiohack View Post
    Hi;

    It looks OE to me. Also I have seen the small deformations in the tangental surrounds visible in your picture at just after 2 O'clock on other known OEM JBL 1” diaphragms.
    Thanks Barry.
    The reason I ask is because the one with the repair tags and missing red-wax seals sounds quieter—by quite a lot. It might even go higher but often sounds distorted, compared to the sealed one. Both measure the same resistance. Well 5.5. "Good" one measures 6.1. I was running them straight, not through a network (bass turned down and both off the same channel at the same time). I hate to open the sealed one, but I'm pretty sure the foam damper disc will be in just as bad shape! And yet it sounds fine?

    I've only just opened the crossovers to find that other than corroded structure on the 3-way switch, they seem to be fine and continuity checks out. I'll find a schematic and see what that shows later.

    Here's what the drivers look like cleaned up:



    The seller didn't seem to know anything about where the clamps went, so I'm looking for a pair, or at least one.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    @Phil,

    Is the gap of the bad driver free of rust ? ( rust will act to lower the effective BL of the coil/magnet assembly )

    In your pics, one driver looks to have suffered more rust damage.


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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Earl K View Post
    @Phil,

    Is the gap of the bad driver free of rust ? ( rust will act to lower the effective BL of the coil/magnet assembly )

    In your pics, one driver looks to have suffered more rust damage.

    Earl,
    Thanks for the suggestion. When I took it apart and changed the damper foam I took out the diaphragm and blew out everything. Everything looked okay but I certainly could have missed some corrosion. There was plenty of it on the outside. Maybe I'll take it apart again and pay careful attention to the gap. It's easy enough to do.

    I've had one of the early grey versions for over 50-years and never got around to getting a second, so my goal of having one more working one has been achieved. Though nothing wrong with a functioning spare!

    Now I need to find a mounting clamp without buying more whole drivers.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Administrator Mr. Widget's Avatar
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    Looking good... hopefully you will get them sounding that way too.


    Widget

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    Senior Member jbl4ever's Avatar
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    Phil, take some white card stock and go around the gap and see if it comes out orange or brown. Then use some tape to clean out the gap

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    Senior Member RMC's Avatar
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    Nice cleaning job.

    RE Both measure the same resistance. Well 5.5. "Good" one measures 6.1.

    FYI, JBL factory DCR specs for LE 175: min 5.9 ohm, max 7.0 ohm (same numbers for the LE 175 DLH you also have).

    So one is a bit low, maybe the more rusted one?? And the other is obviously in the range.

    Hopefully this will help you.
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    Thanks for the thoughts and helpful tips. I'll give them a try, perhaps this evening. Back to work today.

    I realize the unopened one "sounds" fine but what are your thoughts about the foam damper deterioration? Everyone here mentions the issue whenever someone acquires any of the titanium HF drivers from 35ti on up. Even the damper in my 2425J had foam deterioration. Luckily that part was available from JBL and there were no red-wax seals to violate. Is it better to leave the wax seals intact, or to perform what appears to be needed regular maintenance?
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Quote Originally Posted by BMWCCA View Post
    Thanks for the thoughts and helpful tips. I'll give them a try, perhaps this evening. Back to work today.

    I realize the unopened one "sounds" fine but what are your thoughts about the foam damper deterioration? Everyone here mentions the issue whenever someone acquires any of the titanium HF drivers from 35ti on up. Even the damper in my 2425J had foam deterioration. Luckily that part was available from JBL and there were no red-wax seals to violate. Is it better to leave the wax seals intact, or to perform what appears to be needed regular maintenance?
    Hi Phil,

    I have a pair of old 2410's ( the pro equivalent to the le175 ) needing new foams in the back-caps ( I have the same bad foam in every ferrite magnet 2425/6/7 I own > plus a pair of old 2470's I have here ) .
    - The foam turns to mush after a couple of decades no matter what the model.

    I've never seen you sell off much of any JBL, so I'd forget about the wax seals and just replace the foam.

    BTW, that ( pictured ) diaphragm looks much like my 2410 diaphragms, though shinier ( mine are obviously more aged > due to the discoloration of the aluminum pantina ).
    - My two ( very sketchy ) 2420 diaphragms have 3 metal shims that are absent on my 2410 diaphragms.

    It's always possible that your driver needs a remag ( maybe GPA would do that ) .


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    Took the opened one apart and ran card-stock through the gap, then painters tape. Didn't pick up much of anything. Put it back together and it's still very quiet and sounds distorted to me sitting next to the other playing from the same input. The distortion I hear in the opened-one makes me think the diaphragm is bad. Maybe it was never replaced and just opened? I assume they both came together originally because of the sequential serial numbers but the repair tags on them obviously indicate someone looked at them at some time.

    Luckily my 5-decade goal was really to find one working one (cheap), so that's accomplished. The crossovers seem to be working fine. I'm assuming they are N1200s since they have the 3-position switch and judging by the components with them. Best I can tell those had a stick-on label not painted or engraved on the square section on their backs. These are the later ones, not the chicken-head version. Continuity through them is all I checked and then hooked each up to the driver. Played fine.

    If I choose to populate the C35s I bought decades ago to replace my C37 and some '50s Acousticraft or whatever my Dad had, and not play with tri-amping with the Crown crossovers just yet, is there a simple circuit that would accomplish the same filter as an N7000 for the 075s? I guess I'm still in need of the mounting clamp for the 1217-1290 horn. The previous owner apparently burned the original cabinets and even sifted through the burn pit for me. He said he remembered unbolting the horns from the front of the baffle but said there were no clamps. I know that's not possible but I've burned all the goodwill I think he has in him, and I'm grateful for what he's offered. It is what it is! I know the one I installed in the C37 over 40-years ago says "Jim Lansing Signature" on it and I recall it being grey. It fit in the cabinet without any modifications once the wood blanking plate was removed so I assume it had the clamp. I'll find out when I see it for the first time in almost 50-years in the coming weeks.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Member Radley's Avatar
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    From the photos it looks like the diaphragm is out of round?

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    Even if the foams are shot, unless you touch it or jostle the driver somehow, they tend to stay intact, especially those that leaned back all of their life (e.g., L200/L300). Touching it will instantly disintegrate it though.

    The marks on the diaphragm are from when some ham-fisted person went in there and disconnected the leads without securing them. The horseshoe clips are ferrous and if let go in proximity will be drawn to the magnet through the diaphragm, striking the diaphragm and often leaving a pair of "vampire bites". It typically seems to do no real harm.

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    Swap the diaphragms. If the problem moves with the diaphragm replace it, if it stays with the driver probably time to demagnetize them both.


    Quote Originally Posted by BMWCCA View Post
    Thanks Barry.
    The reason I ask is because the one with the repair tags and missing red-wax seals sounds quieter—by quite a lot. It might even go higher but often sounds distorted, compared to the sealed one. Both measure the same resistance. Well 5.5. "Good" one measures 6.1. I was running them straight, not through a network (bass turned down and both off the same channel at the same time). I hate to open the sealed one, but I'm pretty sure the foam damper disc will be in just as bad shape! And yet it sounds fine?

    I've only just opened the crossovers to find that other than corroded structure on the 3-way switch, they seem to be fine and continuity checks out. I'll find a schematic and see what that shows later.

    Here's what the drivers look like cleaned up:



    The seller didn't seem to know anything about where the clamps went, so I'm looking for a pair, or at least one.

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