Page 1 of 7 123 ... LastLast
Results 1 to 15 of 104

Thread: Please help with 128H's in L150A's. :)

  1. #1
    Member DerekTheGreat's Avatar
    Join Date
    Jul 2019
    Location
    Warren, MI
    Posts
    58

    Please help with 128H's in L150A's. :)

    Hello everyone!

    I'm Derek and this is my first post to the forum after much reading and such. I in no way consider myself to be "great" haha. That just came from what I named my Warrior in Diablo I all those years ago. Royal warrior should have some sort of fancy name, right? I've always been a JBL fan, never heard of them until I got a set to compliment some Bose 301's I think they were. Dad (I was 16 or 17 at the time) picked up a set of JBL Northridge S26II's for Christmas which were substantially cheaper than the 301's. Well, they sounded substantially better in every way! Bose stuff couldn't handle the 75 watt Kenwood they were hooked up to and sounded muddy unless I was listening at low levels, real good with spoken voice but that's it. Anyway, I dug deeper into JBL history & lore and really became hooked on them after listening but then after learning that most studios back in the day were outfitted with JBL monitors and then I began to pay attention when I went to concerts and saw JBL's everywhere... Later bought a 1988 Lincoln Town Car with the optional Ford-JBL sound system and it is incredible, really advanced for the time if you ask me. Receiver that acted as a preamp and fed a separate big ole honking amplifier in the trunk. Incredible at any volume. The speakers I use in other cars, as to this day they're hard to beat when acquired for the junkyard pickin' price..

    Anyway, about a three months ago I seriously started getting into vintage audio gear. My dad had a Marantz 2275 he bought new and kept up until I was about ten. I always loved the look of it and said I'd get one some day. Well, I never expected them to be so expensive or desirable so it took awhile to get to a place where now I can start having fun I listen to mostly rock from the 50's to present. I like stuff that sounds organic and like five people can sit down and make music with minimal equipment. I will listen to highly polished stuff like Steely Dan or the Eagles, those guys are great too. New Kid in Town or Hotel California. Euphoria to my ears. Or Spill the Wine by War. Close eyes. Drift away... Well I wanted to recreate a decent system from back in the day to better enjoy my favorite music and channel my dad somewhat..

    Long story short of it is I had a pair of JBL LX44's I had refoamed and then purchased a Marantz 4300 to power them. Well, that sounded really good but I felt the Marantz was over kill for those LX's. So I hopped on Craigslist and began searching for their replacement.. I chose the L150A's over a set of Klipsch Cornwalls. I unfortunately couldn't listen to them so I pushed the woofers in gently at the time and didn't notice any rubbing. Cabinets looked pretty good overall, none of the dust caps were pushed in and the seller claimed a recent refoam job on all the drivers. Score, right? Well, I didn't get them for $20 like all the other threads I've seen though haha.. Anyway, I get them home, hook them to the 4300 and I immediately noticed the woofers made a popping sound at higher volumes, like the voice coil reach maximum excursion or something. I am no way an expert, this experience has been teaching me so much.. Well so I did more reading and come to find out that the L150A's are supposedly power hungry and that many say you really make these things shine when you feed them 200watts or more. Great. I have to spend more money... So I went and bought me a Marantz 3600 Pre-Amp and then a Marantz 510M power amp to match. (Anyone want a minty 4300???) Oh god, they were right! The soundstage was fuller, more articulate and the bass was fuller and richer than before. I let that go for a few days and then tried the test.. Hotel California, right where the drum kicks in in the beginning.. ...Dum-dum-POP! Sadness. Woofers still pop when driven semi hard. I took both woofers out and can't tell if they've been reconed before or not. The back sides are nice and textury as I've seen in other people's photos with white crayon like model numbers on them. Color is a blackish purple. Fronts are white as they should be. Maybe they were painted? I dunno. When I push the woofers out by hand gently, I can feel something rubbing, which must be the popping I hear. So I read if you flip the woofers 180 degrees you might be able to eliminate that popping. Did that. Much better but still there. Then I contacted a well known JBL specialist in the area and went to get her evaluation. She definitely noticed something when they were on the bench. Suggested the previous refoam job wasn't done right and re did the one woofer. Still noticed the pop on both speakers but one does it way sooner than the other. Can't remember which one was done. So I talked with her again yesterday and now we're going to try a full recone but I'm going to lose that trademark white woofer...

    Questions boil down to:
    1) What do you guys think the problem is and have you encountered this before?? What fixed it or is this normal?
    2) Can I paint the woofers white or will this color/change the sound? If you recommend painting, what color/product is the best match?
    3) I need to touch up the low gloss black on the front of the cabinets. What product is the best match for touchups?

    Thank you so much for reading through my long winded first post! I appreciate all input, feel free to go off topic too.

  2. #2
    Member DerekTheGreat's Avatar
    Join Date
    Jul 2019
    Location
    Warren, MI
    Posts
    58
    35 views and not a single response?

    So no one has encountered a woofer which pops when driven moderately hard?

    No one has an accurate recommendation of paint to match JBL's low gloss black found on a L150A?

    No one has an accurate recommendation of paint to match JBL's white on the 128H woofer?

  3. #3
    Senior Member
    Join Date
    Feb 2018
    Location
    Annapolis, MD
    Posts
    172
    I haven't encountered the problem you speak of but there shouldn't be ANY rubbing.

    The JBL 128H (white) cone kits are still available from JBL so you should be able to get the original look. The only thing that will be notably different is the glue that holds the dome down. At the factory, they used a different glue plus accelerant to get the hard glue ring that doesn't run/sink. When gluing down the dome on an Aquaplas driver, as the glue dries, it will sink some and also separate a little so you will see a bit violet color around the edges of the glue. It is also very hard to get a uniform ring on an aqualas driver as the surface of the cone is quite rough so again, the glue will want to run with the surface regardless of how the tech laid the glue down.

    If a full recone is being done, be sure that the air gap is checked for clearance. It should allow a .057" pin to pass through the entire way around (though it will be quite snug, it shouldn't bind). I have had to tell some customers, over the years, that a pole piece has shifted and that we cannot recone the driver anymore. I have heard that there are some places that will attempt to recenter a permanent magnet driver but I'm definitely not one of them.

  4. #4
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    9,932
    Quote Originally Posted by DerekTheGreat View Post
    35 views and not a single response?

    So no one has encountered a woofer which pops when driven moderately hard?

    No one has an accurate recommendation of paint to match JBL's low gloss black found on a L150A?

    No one has an accurate recommendation of paint to match JBL's white on the 128H woofer?
    Patience my friend... welcome to the LH Forum.

    If your local reconer says the new cone will be gray instead of white it may be a JBL 128H-1 kit or an aftermarket kit. Correct replacement kits from JBL have become more and more rare. I'm not even sure if any new recone kits are being manufactured. Everything in the supply chain may be from past production... don't know, I'm just speculating.

    In any event, I don't know what the difference is between the 128H-1 and the 128H, could be cosmetic, could be more significant. I would only go with an after market kit as a last resort. If your reconer can't get the correct white 128H kits, it is possible to find NOS kits, or perhaps a different repair shop has a pair in their inventory.

    Also, I would not paint the cone white. It will never really look right and you will be changing it's mass and may cause other problems.


    Widget

  5. #5
    Member DerekTheGreat's Avatar
    Join Date
    Jul 2019
    Location
    Warren, MI
    Posts
    58
    Quote Originally Posted by sguttag View Post
    I haven't encountered the problem you speak of but there shouldn't be ANY rubbing.

    The JBL 128H (white) cone kits are still available from JBL so you should be able to get the original look. The only thing that will be notably different is the glue that holds the dome down. At the factory, they used a different glue plus accelerant to get the hard glue ring that doesn't run/sink. When gluing down the dome on an Aquaplas driver, as the glue dries, it will sink some and also separate a little so you will see a bit violet color around the edges of the glue. It is also very hard to get a uniform ring on an aqualas driver as the surface of the cone is quite rough so again, the glue will want to run with the surface regardless of how the tech laid the glue down.

    If a full recone is being done, be sure that the air gap is checked for clearance. It should allow a .057" pin to pass through the entire way around (though it will be quite snug, it shouldn't bind). I have had to tell some customers, over the years, that a pole piece has shifted and that we cannot recone the driver anymore. I have heard that there are some places that will attempt to recenter a permanent magnet driver but I'm definitely not one of them.
    I've looked and searched other threads and such, no such luck for the white woofer. These are the best I can come up with:
    https://reconingspeakers.com/product...et-recone-kit/
    https://reconingspeakers.com/product...h1-recone-kit/

    I really hope the pole piece is ok. Hopefully she knows to check that. Says she's been doing JBL's since 1980...

    Quote Originally Posted by Mr. Widget View Post
    Patience my friend... welcome to the LH Forum.

    If your local reconer says the new cone will be gray instead of white it may be a JBL 128H-1 kit or an aftermarket kit. Correct replacement kits from JBL have become more and more rare. I'm not even sure if any new recone kits are being manufactured. Everything in the supply chain may be from past production... don't know, I'm just speculating.

    In any event, I don't know what the difference is between the 128H-1 and the 128H, could be cosmetic, could be more significant. I would only go with an after market kit as a last resort. If your reconer can't get the correct white 128H kits, it is possible to find NOS kits, or perhaps a different repair shop has a pair in their inventory.

    Also, I would not paint the cone white. It will never really look right and you will be changing it's mass and may cause other problems.


    Widget
    She says the cone will be black, or like the ones I linked above which are like the ones already on my woofers, a dark purplish color. I've stressed that if the texture on the rear of the new cones she ordered doesn't match my originals then I'd like her to order one of the kits above. I'm really not sure if my woofers have already been reconed. The guy I bought them off of told me they were refoamed, that was it. The pics I've see of other 128H's online vary from the textured rear cone to a smooth rear cone. I've got NFC, other than I'd like them to perform again. Take it from me, never buy a used speaker unless you can listen to it yourself. It's looking like I should have sold these things rather than deal with it.. I wonder if I would have been better off with the Cornwalls...

    I don't like the idea of painting them, honestly. But, I'm sure if they aren't white then the value of these things goes right in the toilet. I normally wouldn't care too much about value but the idea was to sell these once I got (and liked) a set of L220's. If you guys know the chemistry of this so called AquaPlas I might be able to whip something up in the lab to duplicate it and spray them myself. Otherwise I'm at the reconer's mercy and I just emailed her with the go ahead to paint the new woofer should she not be able to reuse my original cones.

    Thank you for the replies fellas, I do appreciate it. Normally I am a patient dude but since the woofers have been dropped off I feel I'm running out of time to make a final decision on how to proceed. If anyone knows where I can get a full recone kit with the original white woofers, let me know. But I'd probably need to know by Wednesday..

  6. #6
    Senior Member
    Join Date
    Feb 2018
    Location
    Annapolis, MD
    Posts
    172
    I don't want to argue with you. I'm a certified JBL Pro reconer and I checked TODAY and the C8R128 comes up as an orderable part and the system implies that if I ordered today it would ship within 24-hours.

    Do what you want.

  7. #7
    Senior Member Chris Brown's Avatar
    Join Date
    Jan 2005
    Location
    Northern California
    Posts
    129
    As an owner of a set of L150's, I have personally had my 128H woofers pop on several occasions. A loud, heart-stopping THWACK! as the voice coil hits the pole piece. In my case it was always because I was pushing them too hard with bass heavy content. Nothing I could honestly fault the speakers for. I power mine with 700wpc. Some songs, particularly those with a lot of extremely low-frequency bass, are more "risky" in this regard when playing very loud. Without being there or having any objective measurements to go on, it's difficult to compare your situation to mine. Is it possible that you are simply expecting too much of them? If you're accustomed to playing loud using large subs and are expecting something similar from these, this could easily be the result. They aren't subwoofers and they have their limits, which you must respect (something I end up having to remind myself of, more often than I'd like).

    If they were refoamed poorly, to where the cone is not in it's proper resting location, it could end up hitting the pole piece at less excursion than it should. You see this often when the foam gets glued to the front of the cone instead of the rear, as that sets the cone back compared to where it's intended to be.

    Another thing you might check are the passive radiators. They function in place of a port, and have a direct impact on how the woofer functions. The weights on the back of the passive radiator are adjustable by adding or removing some of the cardboard discs. Have these been adjusted in the past that you know of? It may be allowing the woofer cone to move more freely than intended at the problem frequency.

  8. #8
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    9,932
    Quote Originally Posted by Chris Brown View Post
    Another thing you might check are the passive radiators. They function in place of a port, and have a direct impact on how the woofer functions. The weights on the back of the passive radiator are adjustable by adding or removing some of the cardboard discs. Have these been adjusted in the past that you know of? It may be allowing the woofer cone to move more freely than intended at the problem frequency.
    Or air leaks! If the woofers or the passive radiators are leaking due to micro cracks in the surrounds, or other air leaks, this would also cause the driver to unload and could lead to the VC bottoming out.

    It sounds like the correct kits are still available. I would work with someone who can get the correct kits ASAP before they are NLA.
    I would also check out the passive radiators.


    Widget

  9. #9
    Senior Member Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,103
    Hi Derek,

    As Chris points out have the passive radiator and the driver checked out.

    Itís possible that the system is being over driven or that the passive radiator is not loading the woofer effectively. Sometimes drivers will start sagging if left in the one position without use for a long time,

    You may also want to consider a sub sonic filter to remove low bass information that would otherwise cause large driver excursions below the system resonance. Typically this is at or below 30 hertz. These consumer systems are usually tuned between 29-34 hertz and of tuned correctly will demonstrate maximum loading in the driver in this region and the passive radiator will be doing all the work.

    My suggestion to get both enclosures checked out and go on the recommendations of your reconer.

  10. #10
    Member DerekTheGreat's Avatar
    Join Date
    Jul 2019
    Location
    Warren, MI
    Posts
    58
    Quote Originally Posted by sguttag View Post
    I don't want to argue with you. I'm a certified JBL Pro reconer and I checked TODAY and the C8R128 comes up as an orderable part and the system implies that if I ordered today it would ship within 24-hours.

    Do what you want.
    I'm not sure why you were offended with my last message, it isn't my intent to argue on here, but to learn. Nor am I trying to imply you don't have experience. I was simply illustrating that I'm not the typical newbie and provide background information; I tried my best to search and find the right parts but came back empty handed. For example, C8R128 is indeed the correct part number but the pics displayed in the links I've linked on here or came across otherwise either show a black woofer without texture on the rear side or the purplish woofer like already on my speakers but without the white AquaPlas coating. If anything, I was hoping you or someone else could point me in the direction of a source who still has NOS 128H recone kits in stock or who wouldn't mind parting from a pair. If the link you mentioned is the right part with white AquaPlas on the woofer, please let me know how to order it, I'd really appreciate it.

    Quote Originally Posted by Chris Brown View Post
    As an owner of a set of L150's, I have personally had my 128H woofers pop on several occasions. A loud, heart-stopping THWACK! as the voice coil hits the pole piece. In my case it was always because I was pushing them too hard with bass heavy content. Nothing I could honestly fault the speakers for. I power mine with 700wpc. Some songs, particularly those with a lot of extremely low-frequency bass, are more "risky" in this regard when playing very loud. Without being there or having any objective measurements to go on, it's difficult to compare your situation to mine. Is it possible that you are simply expecting too much of them? If you're accustomed to playing loud using large subs and are expecting something similar from these, this could easily be the result. They aren't subwoofers and they have their limits, which you must respect (something I end up having to remind myself of, more often than I'd like).

    If they were refoamed poorly, to where the cone is not in it's proper resting location, it could end up hitting the pole piece at less excursion than it should. You see this often when the foam gets glued to the front of the cone instead of the rear, as that sets the cone back compared to where it's intended to be.

    Another thing you might check are the passive radiators. They function in place of a port, and have a direct impact on how the woofer functions. The weights on the back of the passive radiator are adjustable by adding or removing some of the cardboard discs. Have these been adjusted in the past that you know of? It may be allowing the woofer cone to move more freely than intended at the problem frequency.
    Quote Originally Posted by Mr. Widget View Post
    Or air leaks! If the woofers or the passive radiators are leaking due to micro cracks in the surrounds, or other air leaks, this would also cause the driver to unload and could lead to the VC bottoming out.

    It sounds like the correct kits are still available. I would work with someone who can get the correct kits ASAP before they are NLA.
    I would also check out the passive radiators.


    Widget
    Thank you for the replies, Chris & Widget!
    Driving them too hard has crossed my mind. Initially they were powered with a 100wpc Marantz 4300, and I heard the popping with that with the volume at about 66 or 75% on something like Steely Dan or Hotel California by the Eagles. So I thought they were underpowered as I came across information from other Forums where people said L150's really need 200wpc or more to shine. I thought I was causing them to clip.. So I went and spent more money on a Marantz 510M and Marantz 3600 preamp. Still the same problem. So I flipped the woofers 180 degrees after more reading and that made a big difference. One woofer hardly did it any more and the other could be pushed much harder before I'd get that pop. The only real bass heavy track I listened to is "You Can't Touch This" by MC Hammer just to immediately see if what I did made a difference. The subwoofer & floor standers downstairs (Two JBL Northridge E250P's & a pair of E90's) Handled it no problem. They're powered by a Marantz SR7005. Interesting to note that the L150A's were playing significantly louder and that like others mentioned, I've got that system crossed over so the subs handle everything below 60 or 90hz as they're only 8 inchers.

    But, when I had the woofers out I moved the woofer up as and could feel what seemed to be the voice coil rubbing on the pole piece or something. There was still about 1/4" of travel left. I assume this is the cause for the noise I hear when the woofer quickly hits that rub spot, kinda sounded similar when I quickly did it by hand.. Which also caused me to hop even further onto the "these need to be reconed or refoamed" train.

    I have not looked into the passive radiators. They were also refoamed. Woofers look fine though, surrounds seem nice and supple and I believe each has four cardboard discs on the back. How can I test if they're sealed properly? Any sort of tap on the 128H's causes them to move and if you tap the radiators, the 128H woofer will move too. Seeing as the volume inside the cabinet is large I'm surprised to see that. So I assume they're sealed? However, if I hold either woofer back, the other will return to it's original resting position within short order. Both cabinets behave similarly.

    Quote Originally Posted by Ian Mackenzie View Post
    Hi Derek,

    As Chris points out have the passive radiator and the driver checked out.

    It’s possible that the system is being over driven or that the passive radiator is not loading the woofer effectively. Sometimes drivers will start sagging if left in the one position without use for a long time,

    You may also want to consider a sub sonic filter to remove low bass information that would otherwise cause large driver excursions below the system resonance. Typically this is at or below 30 hertz. These consumer systems are usually tuned between 29-34 hertz and of tuned correctly will demonstrate maximum loading in the driver in this region and the passive radiator will be doing all the work.

    My suggestion to get both enclosures checked out and go on the recommendations of your reconer.
    Thank you for the response, Ian!

    My preamp does have a 30hz filter and I was thinking of using it. I just haven't because I read some sales literature for the 150's and I remember reading something along the lines of "If the bass information is there, you will hear it." And I very much like how these things sound, especially at lower volumes. But I could just enable the filter for when I'm listening hard. Also, I listen to rock & roll mostly, nothing with artificial beats or drum machines aside from that MC Hammer tune to test woofer excursion. How would I go about tuning the radiators? Wouldn't I want to add more mass, not less? I'm not sure at all.

    You're right about the driver sag. I read about that on another forum or maybe it was a thread from this one. How I got the idea to flip my woofers 180 degrees and that pretty much cleared up everything. Which is what got me on the track of "I need to have these refoamed or reconed." Initially my reconer thought they might need to just be refoamed. On her test bench the one sounded like it had a rattle at 30hz but she tried to recenter the cone with a new refoam job and it didn't change anything. The other woofer she couldn't get to make the noise, must be the one I really don't have a problem with.. But she said she didn't like the idea of a recone, told me the white woofers were discontinued and wanted to try and save mine. Although honestly, I don't think mine are originals. The cones' backside reads "129H". What does that say to you guys? She said they were though. I would just expect that for a woofer from 1982ish would be dirtier or something like the photos I've seen online. I've still got a lot to learn though!

    Thanks again for the replies and your time, I really appreciate them!

  11. #11
    Senior Member Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,103
    Without a pic itís hard to know.

    Btw adding a sub into the system might be a good idea when you want to turn it up and cross the L150ís at a point that lowers the excursion on the woofers.

  12. #12
    Member DerekTheGreat's Avatar
    Join Date
    Jul 2019
    Location
    Warren, MI
    Posts
    58
    I'll see if I have any pics of my woofers but they look exactly like these only the chalk marks say 129H and the fronts are white. Which is why I don't think mine are original..
    https://reconingspeakers.com/product...et-recone-kit/

    But, when I look at the discontinued, 100% accurate recone kit, the woofer is like mine, AquaPlas on the front, purplish textured rear... https://reconingspeakers.com/product...8h-recone-kit/

    Would a 2213H fit and be a suitable replacement??
    https://reverb.com/item/25895014-jbl...fer-2213h-grey

  13. #13
    Senior Member
    Join Date
    Feb 2018
    Location
    Annapolis, MD
    Posts
    172
    Any JBL Pro recone center can order the part but what we can't do is sell them as a retail part. They can only be sold as part of a recone. So whomever you are using to recone your drivers, if they are a genuine JBL recone center can get the proper cone kit for you. You won't (or shouldn't) find them for sale on line since it is a violation of JBL's rules. We can sell diaphragms all day long but not recone kits. I'm not saying that you won't find some place that will, I'm saying that they are not supposed to. However, taking your drivers to a JBL recone center should get you the cones you want in your drivers.

  14. #14
    Member DerekTheGreat's Avatar
    Join Date
    Jul 2019
    Location
    Warren, MI
    Posts
    58
    Quote Originally Posted by sguttag View Post
    Any JBL Pro recone center can order the part but what we can't do is sell them as a retail part. They can only be sold as part of a recone. So whomever you are using to recone your drivers, if they are a genuine JBL recone center can get the proper cone kit for you. You won't (or shouldn't) find them for sale on line since it is a violation of JBL's rules. We can sell diaphragms all day long but not recone kits. I'm not saying that you won't find some place that will, I'm saying that they are not supposed to. However, taking your drivers to a JBL recone center should get you the cones you want in your drivers.
    Really? I wish I had known that before I dropped them off with her. She might've been part of a JBL outfit years ago but it's a solo thing for her now. I looked her up specifically because I had my LX44's refoamed by a local place and wasn't happy with them.

    WELL.. I just looked up service centers and she came up in the search...
    https://pro.harman.com/service_cente...&commit=Search

    Don't know why she is telling me that the part isn't available then. Believe me, we spent at least an hour discussing stuff. Could you order them? What happens when you try and place an order? I'd like the proper cone!

  15. #15
    Senior Member rdgrimes's Avatar
    Join Date
    Aug 2008
    Location
    New Mexico, USA
    Posts
    2,166
    Isn't the 128H one of them with 2 different cones seen coming from the factory? I seem to recall that they used different foam surrounds on the 2 different revisions. I don't suppose it would matter if you're re-coning, but there still might be more than one part number floating around?

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. New owner of old L150A's here! Help please.
    By evans224 in forum Lansing Product General Information
    Replies: 8
    Last Post: 01-19-2005, 11:44 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •