JBL 4312's Anyone rebuild the crossover?

nadude98

7MGTE Power!
I have a pair of 4312's that I am not happy with the sound out of one of the pair's tweeter and mid. From what I read they might need a recap of the crossover.

Does anyone have any experience with getting to the crossover to rebuild? I have checked the Lansing Heritage Site too...Found some info but I would like to here someones personal experience!:yes:
 
I checked out that thread and there is a lot of useful info... :yes:

I took out the crossovers and I found out I have the 3112C crossover. I am planning to do the upgrade for the original sound with the improvement....:D

Put the parts from Parts Express on my wish list:smoke: There is not a big hurry as I am planning (so far) with using them with my SX1250 which is out for a :music:rebuild
 
Hello! Is anyone still out there on this ancient thread?

I think the world needs to know how amazing the 4312a Control Monitors are (or maybe better to keep the secret to ourselves..). But they are bonkers good!

I need thorough guidance on upadating the crossovers and tone controls on my pair. I also need to know what tools I need and what electrical testing equipment is necessary to test the state of tweeters, midrange and woofer. I will not be doing any cabinet refinishing at this time, but might consider adding rock wool on the inside just to tighten them up a bit.

I bought from eBay a set of 4312a crossovers and they are on their way, this way if I mess anything up the originals are fully intact.

Things I have done to improve the sound of these already are: super-dense socks rolled and stuffed into bass ports, using painters tape I have obscured all drivers with various layers of fabric--these suckers are forward and often brutal. Placement also is extremely important with these speaker. I have woofer down and midranges on the outside, this allowed me to push them back a bit more and toe them in a bit less to give me a bit wider sweet spot, still just a little bigger than a human head.

Please be in touch JBL geniuses!

Brettra2@yahoo.com

Thanks!
 
I am not aware of what's out there to change the crossovers. Mine are NOS and I think they're mylar caps which really wouldn't have degraded.

You say that you like the sound, and they are an extremely flat speaker, what are you trying to change?
 
I am not aware of what's out there to change the crossovers. Mine are NOS and I think they're mylar caps which really wouldn't have degraded.

You say that you like the sound, and they are an extremely flat speaker, what are you trying to change?

Agreed. I wouldn't change any values. These speakers are special due to their extreme flatness.
 
I'm baffled (pun intended) by plugging the ports and "obscuring" the drivers on a monitor with flat response, especially since you gush about how good they are.

If you don't like the sound of these speakers, I suggest finding a design that suits your taste rather than to muffle these.

One thing that I can add however, there are some problems with older speakers and these are the common ones with these drivers:

Woofers: Surrounds can become stiff with age, doping gets hard

The magnet is ported with foam damping material, which degrades and sometimes gets into the voice coil air gap

In one of mine the tinsel was so close to the frame that it touched and buzzed, needed a terminal adjustment

Tweeters: There is a foam damping pad under the dome, which breaks down and loses its damping properties. In some I have read that it can become a mush with the ferrofluid in it. NLA parts, you can only guess at the proper durometers (two pads stacked) at this point or use something completely different as one ebay seller does, ... and assume that it is close enough.

Unplugging the leads sometimes will pull on the tiny wire to the voice coil and break it.
 
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