JBL 4343 Crossover

[joezeppi]

I, too, have a pair of JBL 4343 systems and would like a Crossover parts list and source for the parts, as I am handy with soldering circuit connections. Some of the existing parts are submerged in some sort of resin and there's no way I know of to release those parts without destroying something.

Thanks in advance.

 

[PeteMcK]

4343 crossover modifications

 

[georgebrooke]

4343 Crossover "Gunk" removal

I, too, have a pair of JBL 4343 systems and would like a Crossover parts list and source for the parts, as I am handy with soldering circuit connections. Some of the existing parts are submerged in some sort of resin and there's no way I know of to release those parts without destroying something.

Thanks in advance.

Hi,

When I went through this exercise I left the resin alone (on my L300 project). However, after publishing what I had done I was told by email that the "resin" can be removed by gentle heating and just poured out. I must admit that I never tried this but I am sure that several on this forum will have experience of the method.
Another view is to preserve the original crossover, for later resale of the speaker, and to build a new crossover externally mounted for easy modification. There are plenty of exotic crossover improvements for these speakers, in particular complete rebuild to allow batteries to be used to improve the (dual) capacitor performance. This is all covered in the 4343 threads.
George

 

[darkmatter]

Hi George,

Do you know how the heat was applied to remove the resin material? and indeed what type it was?

Thanks

Simon

 

[georgebrooke]

Hi George,

Do you know how the heat was applied to remove the resin material? and indeed what type it was?

Thanks

Simon

Hi Simon,

I just reread my original notes on this..... it came from an L300 upgrade article that I wrote years ago. All I have is that "gentle heat is applied" which allows the resin (or whatever it is) to be poured out. I believe that the "gentle heat" was applied by an oven. If you can see a corner of resin free of components it might be worth experimenting with a low-setting on a hot air gun, to see how sensitive the resin is to heat. For many components 50C is a tolerable temperature, but there must be people or threads in this forum that can guide you more carefully. Just think of the consequences of a cooked crossover before jumping in to this.
Please let me know if you get some definitive information on this.

George

 

[georgebrooke]

All Things JBL 4343

Hi,
for an exhaustive (and exhausting) set of information and discussion (some educated and some not) including the usual "Flames On" stuff, see 4343 crossover modifications
If you visit Lansing Heritage Forums you wil be overwhelmed with information.. but I can recommend postings by Heather James, Ian mckenzie, Guido, Richluvsound and others too numerous to mention.

George

 

[Robh3606]

Hello Joe

Best bet would be to keep the original crossover for resale reasons and just build up a second set with new parts. If you are not going to bi-amp them get rid of that damn switch. You can also replace the potentiometers if they have become noisy and don't responds well to a cleaning.

When I built my 4344's I set them up for bi-amp only. You don't need to use the original active JBL crossovers with them to get good results. Any decent 2 way active will work just fine in the 300Hz range with them. Have fun!

Rob🙂

http://www.jblproservice.com/pdf/Network Schematics/3143 Network.pdf

 

[georgebrooke]

4343 crossover

Hi Rob,

I think that is the way that I shall be going. I plan to use the JBL 2-way active crossovers and to continue to use passive crossover for the non-bass section. As you say, preserving the original crossover is sensible for resale value. Also, it then becomes possible to use a modern design for the 4343 crossover rather than just butchering the (classic) original.... and getting rid of that lousy switch too.