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lodoc
12-06-2004, 07:22 PM
I have owned a pair of JBL Jubals since approx 1974 and continue to enjoy them regularly. Both woofers (126 A ) have been reconed one or two times. Recently I noted the absence of bass from one of the speakers and pulled it out of the cabinet. The spider has come loose from the basket but the foam and cone look good. I have read all the posts using 'adhesive' to search and have seen responses ranging from cyanoacrylate to 2-pt epoxy to silicone RTV.

My question is two part:
1) can I just reglue this and what type of adhesive will work best?
2) if I need to send them out again who in the field is recommended to do the repair? I'd like them to hold up for somewhat longer than the last repair which lasted only a few years. I don't abuse them but they are driven hard at times with a reasonably low distortion HK amplifier and mostly digital signals. BTW- I do have teenagers that have come to appreciate their quality and I don't always know what goes on when I am not home.

thanks in advance for any input to my first post on this forum
karl

GordonW
12-06-2004, 08:05 PM
Well, to do the job right, you'll first need to remove the dustcap, and shim the voice coil. As for adhesive- for this application, I'd be inclined to use 2-part epoxy, either the 5 minute or 30 minute variety. This will allow you to coat both surfaces without worrying about the glue hardening up before you can get things assembled properly. Also, it'll allow you to play around with the spider mounting alignment, to make sure it's dead on straight.

Don't use a huge amount of glue, but do make sure you get both surfaces (basket and spider edge) coated pretty uniformly. Then, push the cone/voice coil down (while making sure the shim is seated firmly in the gap, between the coil and pole piece) to squish the two sides together. With glue on both sides, it should tack together well enough to not have to worry about it pulling up, with epoxy...

Regards,
Gordon.

lodoc
12-06-2004, 08:38 PM
thanks for the input. I was afraid that would be the answer. I was concerned with aligning the voice coil properly in the magnet if I attemped to just 'glue' the spider back onto the basket. my limited knowledge of speakers was just gleaned in the last day or so when I realized they would not be functional for a party tomorrow night and hoped to make a quick repair. may have to plug in the bozaks or advents. some related articles I quickly read indicated alignment and shims. at least I learned some new vocabulary terms such as spider and basket.
once again, time to call a professional.

I should probably have the pair done again..... any recommendations on reputable repair facilities since the repaired / reconed drivers have not seemed to hold up nearly as well as the originals?

Zilch
12-06-2004, 10:06 PM
Find your local authorized JBL Pro Service Center here:

http://www.jblproservice.com/service/index.html

OR, take them back to where they did it the last time and raise holy Hell with them to fix them for free. Teens nothwithstanding, they can NOT have been glued properly.... :mad:

Party? Did someone say, "Party?" :rockon1: :bouncy:

boputnam
12-07-2004, 07:06 AM
lodoc...

Not knowing where you live, Zilch's advice is good. If you are willing to ship, Orange County Speaker (http://www.speakerrepair.com/) does good work.

An alternative, interim possibility - if you're game: You could glue them without removing the dust cover, centering the voice coil using a 30Hz tone. With the surrounds intact (you say), running a 30Hz tone while drying will likely give good centering. It may even be a good enough repair to defer the reconing - if not, you were going to recone them anyway, but this might get those Jubal's into that party!

John
12-07-2004, 12:51 PM
I would try Bo,s advice you have nothing to lose!!! Why mess with the dust cap if you do not have to.

David Dryden
12-07-2004, 01:41 PM
Lodoc,

I told you they'd have the answer! :D Hope you are able to get them repaired without difficulty. Good luck!

lodoc
12-07-2004, 02:00 PM
thanks for the advice. I'll give it a whirl if I can find a 30Hz source - I enjoy good quality equipment but my hobbies include restoring 67 gto convertibles and not stereophonic equipment.

I did hit the link for authorized JBL repair facilities in my area (se michigan).
I realized that was my method of choosing a repair facility the last time the speakers failed since my local high-end audio shop has stopped doing instore repairs. I even recognized the name of the last company I had repair them - though I cannot tell from looking at the speakers if the one
that failed this time was the last one repaired?!? and to be honest I would not use that facility again as they disappointed me by shipping via USPS when they had agreed (and I paid for) UPS 3d shipping and they arrived after an event and I once again had to use my 'second choice' speakers.

so, I am glad to have input on repair facilities with a good track record. the additional shipping cost is marginal and I'd rather have the work done correctly.

have I made a mistake in the past by only having the driver that fails repaired? my limited research in the last day of reading topics on this forum has alluded to having the pair done - 'they both get the same signal - make sure they are done together and match' someone said.

boputnam
12-07-2004, 02:33 PM
I'll give it a whirl if I can find a 30Hz source I Googled and found this Test Tone Generator (http://www.esser.u-net.com/ttg.htm) with a 30-day trial. Looks pretty cool...

As well, Test Tones (http://mdf1.tripod.com/test-tones.html) has some .wav files, but you will need to loop these to get it to run for the duration of the glue setting-up.

If you expand your interest in this nutty hobby :nutz: , you can get the Basszone Test CD (http://www.stryke.com/basszone/) that will keep you sated until you get an oscilloscope and/or tone generator...

...have I made a mistake in the past by only having the driver that fails repaired? my limited research in the last day of reading topics on this forum has alluded to having the pair done That depends. If one get's a hole poked in it, and there's nothing wrong with the other, the answer would seem to be :no: . If they are both aging, and thereby failing, the answer would be :yes: ...

In general, the Rule is - meaning there are by-definition gonna be exceptions - most here prefer to recone to JBL spec by JBL techs. That way, you know your speakers are working fine, and need only worry about your amps... :rotfl:

pelly3s
12-07-2004, 07:16 PM
well the correct glue to use would be Bostic or Moyen cement or the L1300 JBL used to ship with kits. You might be able to find someone who can get their hands on a tube of it and the right dust cap, for example me. I will check tomorrow if I have any tubes at the shop and check on the dust cap to see if I have the right one. You might also want to check with Making Waves in Arizona. I believe they will ship out Moyen cement not 100% sure though. Like I said I'll check the shop tomorrow and get an answer for you tomorrow night.

lodoc
12-07-2004, 09:10 PM
I used another pair of speakers tonight but still interested in attempting repair.....

I cleaned the adhesive from the basket edge. the spider didn't seem to have much if any adhesive adhering to it - seemed to be all on the basket. most solvents wouldn't cut it. alcohol, lacquer thinner, 3M adhesive cleaner......all negative. finally used acetone and it cut the old adhesive - 10 minutes or so with a rag and Q-tips. MEK was the next option but the acetone worked fairly well.

the 30 Hz signal in place of pulling the dust cover and shimming is intriguing and thanks to those with the technical expertise to suggest same....great idea. I just don't have access to the equipment to generate the signal at present.

boputnam
12-08-2004, 07:22 AM
MEK was the next option... Ah, there wasn't a dry eye in the Forum when you mentioned it. Our favorite highly volatile distillate... :nutz:

Don't fool around with substitutes next time: MEK is your friend. ;)

lodoc
12-08-2004, 08:02 AM
MEK it is next time....live and learn. I'll give it a final cleaning with same prior to attempting repair. thanks again to all that have contributed to helping a novice with a problem

I bought the pair of used 126 A's on ebay last pm. I've become frustrated having voids in my audio reproduction abilities. Murphy always seems to show up when I need him least. so I'm going to keep a back-up driver or two available for those times of equipment failure since the main thing I've done to maintain the speakers is to recone the drivers several times in the last 30 yrs. yes, I realize I'm probably setting myself up for failure of another component that I don't have sitting on the shelf. but....is there any significant problem with a 'mismatched' pair regarding wear and tear on the equipment if they sound acceptable to me?

Earl K
12-08-2004, 08:32 AM
MEK it is next time....live and learn.

Well, MEK is a highly volatile ( aromatically ) substance.
( I don't know anything about any "explosive" properties that might accompany that volatility ) .

Use it under very well ventilated conditions.

Used under poorly ventilated conditions - its willfull use is comparable to "glue-sniffing" and all the self-inflicted damage caused by its aromas .

I'm surprised the stuff isn't "banned" or "controlled" in California .

regards <> Earl K

boputnam
12-08-2004, 08:59 AM
...I don't know if its' highly volatile... :yes:

Well ventilated, is certainly advised.

lodoc
12-08-2004, 09:18 AM
I believe it is restricted in california. In michigan you can buy it at any hardware store.

boputnam
12-08-2004, 09:25 AM
Not yet!! It is still available over-the-counter. :p

morbo!
10-25-2005, 08:44 PM
cool edit can produce any tone you want
awsome software

cool edit is good for just about any audio appliction give it a look

louped garouv
10-26-2005, 11:49 AM
I bought the pair of used 126 A's on ebay last pm. ... Murphy always seems to show up when I need him least. so I'm going to keep a back-up driver or two available for those times of equipment failure since the main thing I've done to maintain the speakers is to recone the drivers several times in the last 30 yrs. yes, I realize I'm probably setting myself up for failure of another component that I don't have sitting on the shelf. but....is there any significant problem with a 'mismatched' pair regarding wear and tear on the equipment if they sound acceptable to me?

any word of advise on long term driver storage?

I have heard both

(1) store them in sealed plastic in original boxes (or close approximation) upright (ie oriented as if they were mounted in a cabinet) and

(2) stored upright as if mounted in a cabinet -- tacking them to a piece of plyboard that is vertically oriented is OK


:dont-know

experts?

morbo!
10-26-2005, 03:20 PM
face to face and bolted together then in a larger box if the foams dont protrude past the gasket
if they do your 1st method