surrounds for L300 summits

[DCHAMBERS58]

could someone tell me the part number for foam surrounds for 136A woofers and best place to buy them?

thanks

[grumpy]

http://audioheritage.csdco.com/vbulletin/showpost.php?p=157904&postcount=2

[remusr]

I wouldn't refoam. The surrounds I've seen are stiffer than JBL and raise the Fs 5Hz or more. JBL recones are expensive but that's all I do now.

[Tim Rinkerman]

I re-surrounded the 2231's in my 4333 cabinets and am totally happy with the results....I used "The Speaker Shop" from Rochester NY. The surrounds fit perfectly and for $35.00 for both, was well worth the experience. They give you surrounds, voice coil shims,dust domes,adhesive,gaskets..even an instructional video..I did not remove the original dust domes, I just made sure the voice coil didn't rub as the glue dried. Use a 10hz. tone to move the cone to help center the cone,the spider keeps the assembly pretty well centered. I also re-used the original gaskets..the surrounds edges matched the angle of the cone perfectly,and are impossible to tell that they are not stock. They do soften up a bit after some use, just like a recone....I really don't think it's worth buying a $150.00 cone kit if only the surrounds are bad, the foam is the only part of the assembly that deteriorates.

[remusr]

Tim - have you checked the Fs before or after they were "broken-in"? ie WooferTester2?

[speakerdave]

Another consideration is that the recone kit for that driver is not an exact replacement, but is rather an improved version and is the same kit that is used in the 2235. That kit will also raise the resonance, probably more permanently than a refoam (I've read that it has a stiffer spider--I can't confirm that of my own knowledge). I tried some well broken-in ferrite 2235's in my 4333A's. The bass was better but I felt it was not a good fit in the midrange with the existing crossover. The ferrite 2235 is not exactly the same thing as reconing an Alnico frame with the 2235 kit, but I think the original 2231/136 cones are worth preserving as long as they have not been beat up. I also refoamed my 2231's. They worked just fine. The resonance frequency drops after some use.

David

Edit: There is no JBL part number, by the way. JBL does not support refoams.

[Mr. Widget]

I wouldn't refoam. The surrounds I've seen are stiffer than JBL and raise the Fs 5Hz or more. JBL recones are expensive but that's all I do now.I have no experience with refoaming these woofers however in general I agree with you. Refoams typically are not EXACTLY like a new woofer... that said in the case of a 2231A, I agree with Speakerdave... I would try to preserve the original first. If you want to try out the 2235... there are plenty to play around with. The 2231As are a bit different and examples in excellent condition are far more rare than 2235Hs.


Widget

[GordonW]

I wouldn't refoam. The surrounds I've seen are stiffer than JBL and raise the Fs 5Hz or more. JBL recones are expensive but that's all I do now.

That was a common problem up to 3 years ago... but the modern surrounds for 2231s and 2235s, available from several sources, seem to much more closely mimic the original parameters.

Last 2235H I repaired, Fs after refoaming was just a tad over 21 Hz... with any break-in at all, it'd meet factory spec, easy...


Regards,
Gordon.

[joey]

I have been reading this thread with great interest. My father-in-law recently gave me a pair of L300 Summits. The woofer foam surrounds are totally gone. I have no idea what to do, and reading all the numbers you folks are familiar with hasn't helped. :(

I know the speakers are worth repairing, but I'm lost. Do I have to develop a lot of specialized knowledge in order to get them fixed? Can I simply remove the drivers & ship them off to a good repair shop somewhere? I want to do this job once & right. Thanks for the forum & your insights.

[speakerdave]

I have been reading this thread with great interest. My father-in-law recently gave me a pair of L300 Summits. The woofer foam surrounds are totally gone. I have no idea what to do, and reading all the numbers you folks are familiar with hasn't helped. :(

I know the speakers are worth repairing, but I'm lost. Do I have to develop a lot of specialized knowledge in order to get them fixed? Can I simply remove the drivers & ship them off to a good repair shop somewhere? I want to do this job once & right. Thanks for the forum & your insights.

Your father-in-law is a nice man!

If the woofers are original they are 136's. Don't just send them to any repair shop. Let us help you find a good one. We have members in Utah. Maybe one of them can help us with a suggestion. Failing that, we have a couple of members with shops, although at a greater distance from you. It's possible to do the refoaming wrong, so you want a repairman who knows how and likes old JBL's enough to do it right. The original surround is glued to the back of the cone edge. To put the new one there requires extra time preparing that surface, and we see refoams glued to the front to save that time. It doesn't look right and it forces the cone slightly out of position when done that way.

There's a thread in the forums here showing how to do the foaming; if you are handy with tools you may decide to take it on. We have a source we like for surrounds that is mentioned there:

http://www.audioheritage.org/vbulletin/showthread.php?t=469

David

[Mr. Widget]

I know the speakers are worth repairing, but I'm lost.



If the woofers are original they are 136's. Don't just send them to any repair shop.
The 136s that you most likely have (unless someone did a bad thing) use the same cones as the 2231A that was mentioned earlier. To maintain the original sound of these speakers you should try the refoam route instead of the recone route. You can do this yourself... here is a thread on the procedure:
http://www.audioheritage.org/vbulletin/showthread.php?p=3110

Personally I'd recommend you have it professionally done as Speakerdave recommends and hopefully someone in your area can lead you to a quality shop... there are quite a few lousy shops out there. If you go to a bad shop, at best they will do a messy looking job, but they may glue the new foam on the wrong side of the cone or worse yet not align the cone properly allowing a VC rub causing you to burn up the driver.

I mention all of this not to scare you but to alert you to the possibilities and to give you questions for the shop. Many members here have gone on to doing the work themselves as Bo did in the link above... if you are handy and patient you can do a fine job yourself.


Widget

EDIT: Dave added to his post while I typed... it appears we are pretty much on the same page here.:)

[SEAWOLF97]

I want to do this job once & right.

Unfortunately , you dont just do it just once. Prolly every 15 years, that is about average usefull life of foams.

[speakerdave]

. . . . and reading all the numbers you folks are familiar with hasn't helped. . . .

I remember feeling exactly the same way about the number salad. It's a necessary shorthand you will catch onto well enough if you do much reading here.

136A is the Alnico-motored woofer in the L300, a consumer product.
2231A is the same woofer sold through JBL Pro.
2235H is the later, ferrite magneted woofer of the 2231 style of woofer

4333A is a three-way studio monitor. It is basically the same speaker as the L300 and uses the same components, but in their JBL Pro versions.

The letters after the numbers sometimes refer to impedances, sometimes refer to other model differences, but that would be too confusing to go into right now.

David

[Mr. Widget]

The letters after the numbers sometimes refer to impedances, sometimes refer to other model differences, but that would be too confusing to go into right now.
:rotfl:

It can get very confusing... JBL has been around a long time and they have changed their numbering philosophy several times over the years.... and then there is the changing impedance issues and Bo's favorite, the changing polarity conventions. It just gets better and better. :applaud:


Widget

[remusr]

GordonW - can you provide a source of good surrounds? Both MWA and Rick Cobb's are stiffer and appear to be less open textured than JBL foams in recone kits. OCS appears to have a good product from their website and JBL linkage but will not ship to Canada.
Breakin - I can not measure any longterm changes in Fs with WT2 from playing music for 200 hrs or running at Fs for 4-6 hours at 1/4" amplitude. There is a variable change in Fs if I test with WT2 immediately after running them but they've returned to their "virgin" Fs over a couple days. I should note that I've only tested about a dozen 2231/136A or 2235H so far so it may not be fully representative. I am trying to find 16 Hz Fs 2231/136's for my L300's. The only speakers I have had with lower than stock Fs were 2231's and 2245's with overextension spider stretch damage. Maybe others can comment on what they have measured?

[joey]

Excellent responses, thank you.

I have a workshop full of woodworking tools, but can't manage to cut a straight line on a tablesaw. I knew the L300s were a project, but I don't trust myself to do the fine work that Putnam did in that thread. I'd ruin everything.

On the other hand, every time I hire someone to do something, they screw it up, so I feel I can't go that route either. Hmmm...

If I ever find the nerve/time/foolishness to fix them, what else do I need to know? Does anything ever go wrong w/ the midranges or tweeters? Do I just glue back on the giant black louvers in front of the midrange that have fallen off? Are there tests or mods that I'm supposed to do on the crossover?

[SMKSoundPro]

I have been reconing JBL products and others for over 25 years professionally, and lately, only for my own projects.

I have used the MWA refoam rings and have found them to be adequate. Its just foam! Not rocket science!

I recommend Roger at http://www.soundspeakerrepair.com/default.asp

He is in Tuscon, AZ., and is very conscientious about vintage JBL when you talk to him on his 800 number. Tell him I sent you, and you will be fine.

I also have a very fully equipped wood-working shop, and still managed to cut of one of my fingers on my table saw. My point is: stuff still happens when you're careful.

Congratulations on your L300 Summits. They are outstanding, and quite a prize. Treat them that way, and you will never need anything else!

Signed,

Scott M. Koeller.

[SMKSoundPro]

Excellent responses, thank you.

Do I just glue back on the giant black louvers in front of the midrange that have fallen off? Are there tests or mods that I'm supposed to do on the crossover?


The louvers are called "lenses" just like a pair of eyeglasses correct the anomolies of your eyeball.

They are attached with velcro. The pile side is adhered to the cabinet baffle board, and the hook side is adhered to the lense. Over time, the adhesive can get gooey and not stick, well. I always take an senco upholstery staple gun, like a model JG with 3/8" staples and put a couple in the pile side. An arrow JT-21 will do the same job, but be aware the density of the baffle board. Shorter staples will do a better job than long ones.

Relube the cabinet with watco oil. Let dry. Use a briwax, or Johnson paste wax, and enjoy! Always provide a glass top for someone's inevitable plant they will stick on top of your singing furniture!

I hope this helps.

Scott.

[boputnam]

Its just foam! Not rocket science! Not exactly true - it is not rocket science, but surround compliance does figure into Thiele-Small parameters (not as greatly as does the spider, but it does contribute).


... but the modern (non-OEM) surrounds for 2231s and 2235s, available from several sources, seem to much more closely mimic the original parameters.

Last 2235H I repaired, Fs after refoaming was just a tad over 21 Hz... with any break-in at all, it'd meet factory spec, easy...Yea. It does matter. I know Rick Cobb paid/pays particular attention to get material as close to original spec as practical. In some cases, this has caused him to quit offereing certain surrounds (if my memory holds...).

As Widget (and edge) and others suggest, if you can get a recone done by a qualified JBL reconer, do it. Save the resurround option for situations were kits are no longer to be had...

[speakerdave]

As Widget (and edge) and others suggest, if you can get a recone done by a qualified JBL reconer, do it. Save the resurround option for situations were kits are no longer to be had...

Bo--sounds like you haven't read the thread. Refoaming is what is being suggested here, because in fact exact replacement kits are no longer available for this woofer.

As to the original inquiry--if this is starting to get confusing, go offline with a private message to member "edgewound." He can stay focused and give you guidance and do the work for you, whichever you decide to do.

David

[joey]

Once again, thank you for the excellent, thoughtful responses & for treating the new kid kindly. I'll follow your suggestions. If/when I decide to take action, I'll do my best to provide before & after photos.
I made the very stupid mistake in college of giving away a pair of Acoustic Research AR3as. Time to redeem myself.