ballpein
11-25-2008, 10:14 AM
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.
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.