JBL 4311A - recap and cone repair - recommendations?

[ballpein]

Hey folks,

I've recently acquired a pair of JBL 4311 A's.

They are in fairly good cosmetic condition, apart from some rotten tweeter foam and a small tear in one of the woofer cones, about 3/4 of an inch near the outer edge of the woofer, and the common drip of "molten woofer goop" running down the front of both speakers.

A quick test shows that the tweeters aren't working, not even a crackle when dialling the brilliance knobs. All of the knobs feel a tad off - either too tight, or gravelly - and the presence knobs crackle or cause sound to cut in and out. Even without tweeters, though, these speakers sound great, I'm looking forward to getting them back into full operation.

The tasks as I see them are as follows, I have a few questions about the process and would really appreciate any input:

1) remove tweeters and test. Hopefully the they're not blown, and the issue will be with the crossovers. The tweeters are very reluctant to be removed, it seems folks have good luck with a putty knife or maybe fishing line, and the same would seem to go for removing the woofers, any thoughts? This is the part I'm most apprehensive of, as I'm much more comfortable with electronics than mechanics.

2) recap the crossovers. Elsewhere folks are recommending a combination of Dayton caps with Theta bypass, do folks here have any strong feelings on this combo, or any alternate ideas?

3) replace the mid and tweet L-pads, elsewhere it's been recommended to use 15W, 3/8" shaft L-pads.

4) replace the foam tweeter surrounds.

5) repair the ripped woofer cone. Procedure seems to be to do a sort of paper-mache patch over the rear of the rip with toilet paper or cigarette papers; there is a difference of opinion around the nets on whether one should use a glue that dries stiff (elmers, epoxy, nail polish) or one that dries flexy (silicone, shoe goo, aleene's fabric glue). Any thoughts or suggestions would be much appreciated.

6) replace the tweeters, if necessary.

Thanks in advance for any thoughts or advice,

Dave.

[Doctor_Electron]

Cone repair is not my expertise, but your damage doesn't appear critical in the pix.
I think you will find that removing the Foilcal along the bottom (in order to access the screws which mount the crossover) will be the most difficult task. I am assuming that the 4311s use the same scheme as 4310's. I have seen the procedure described here, so you can do a search for that. But having patience when heating and pulling the Foilcal is paramount to success there unless you have replacements (which I doubt are easy to obtain without getting beat up $ wise "on the bay").
I search often for caps etc. at electronics surplus outfits and have gotten great deals this way, such as a bunch of 20uF teflons from All Electronics Corp (Los Angeles area) for $ 2.50 ea. They sound just fine to me.
I replaced the worn out Lpads in my 4410's with "generic" 50 watt Violets, again a success.
In any case, enjoy the project and results.
"docE"

[SMKSoundPro]

Yes, that is the way to go.

The "rip" you show in the 123a/2212 woofer is no big deal. Brush some "white-out" on it if you choose to. I would choose not.

The tweeters are normally toast in my experience and LE25-2 kits can be had if you know the right guy.

Removing the components from the cabinets can be an exercise, but patience and diligence will prevail. The slim putty knife around the tweets is best. The dropping technique works for the woofs. I dig in and pry with screwdriver against the midrange LE5-2 metal basket. Whatever gets the job done. Grill cloth covers a myriad of mistakes.

Use the heatgun/hairdryer on the foilcal with a slim sharp putty knife to lift just the end near the l-pad knobs. This will expose the mounting screws for the crossover. Be careful when removing the l-pad knobs. They become brittle over time. Find a couple of 8 ohm l-pads from Parts Express to replace the originals. Do not remove the wires of the originals until needed as to keep from getting confused which goes where! (I did it, once!)

Reassemble the crossover. If you choose to go into a hot-rodded cross-over, there are many suggestions, but then is it really a 4311/L100?

I have 8-4311 that play everyday in the main bar for background foreground music/TV audio/jukebox. They work just fine in this area. I also have a pair of 4312's in the Ballroom control booth for monitors for cue, and they are just fine. Not great,...just fine for cue.

What about the box and veneer? Will you be sanding and watco oiling that? They all have dreaded wet planter/pot rings. What about those?

All in all, I hope this helps.

Scotty.