Since the original thread was about the debate between OEM JBL kits vs aftermarket kits, I'll again state that if you want a JBL driver, then you need to buy JBL kits. The OP agreed with that position so I'm not sure what you're doing here with your kits...
...seems like your response may be more appropriate in the for sale section... I'm sure there is a market for your product, but this thread dismisses the entire idea of what you're trying to sell.
Hi guys,
I went for the genuine JBL recone kit for my damaged speaker. The result was very good and I have been completely happy with the decision.
Since then I have moved on to JBL L112 as my main speakers, the 4311B's are stored in a closet for now.
My reason for going back to this thread is that my 4311B's have always seemed a bit unbalanced left to right. At first I thought it was a natural result of one being closer to a corner than the other, but this imbalance has persisted with changed positioning and moving houses. I removed the woofers and measured the DC resistance. This is going from memory now, but I think the reconed one measured about 4.5 ohms and the other one about 3.5 ohms. The lower measured one is the weakest sounding.
I e-mailed the dealer that provided the recone kit I used earlier, but it seems the kits are completely obsolete from JBL at this point.
Too bad, because the reconed one works perfectly and looks stunning, but the other one is a bit faded and with a grayish dust cap. Would have liked to recone it to have balance between the speakers, but it seems this is a no-go unless I stumble upon a NOS recone kit. And they are expensive when they occasionally turn up.
What could be the reason for the weakness in the lower measured woofer? Could it be that some of the windings in the voice coil are shorted, but not all? Would this make it sound weaker?
Any suggestions as to how this can be remedied? Or will I just have to bite the bullet and get another old 2213h woofer which may or may not be equal to the good one that I have?
Any input is greatly appreciated.
-krisonic
You would think that the one with the lower resistance would be louder.
I couldn't tell you if the difference in DC resistance would account for a significant difference in volume but I think further investigation may be necessary. Have you checked the other drivers? Also, those tone adjustment pots tend to oxidize over time, adding resistance to the circuit. You may want to check into them as a possible culprit.
Perhaps you could swap woofers and see if the problem follows the older one.
Good luck,
Warren
DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.
I replaced the l-pads and rebuilt the original crossovers with new capacitors while restoring these speakers, so I do not think the l-pads should be the culprits here. I will see if I can try the woofer swap as you said, to see if the problem follows the driver or not.
A bit of a hassle though, but probably worth a try.
Hi krisonic,Originally Posted by krisonic
If the drivers are AlNiCo, then it is possible that have to be re-magnetized, to reach nominal magnetic flux in the gap. If they are Ferrous, then may be the BL factor is not OK (shorter VC length in the gap).
regrads
ivica
Hi ivica,
The drivers are of the ferrous type, so demagnetization should not be an issue with them.
Do you mean that the voice coil might need to be reseated or that it might have the wrong length? I think the cone is original, so the voice coil should be equal to the one in the genuine JBL recone kit I used for the other driver.
Regards,
krisonic
Hi krisonic,
As BL means= B x L, so if B is correct, the L (length of the wire in the gap) has to to be correct, but the problem is that JBL have not user round wire but rectangular cross-section wire, so using ordinary round wire would not give expected results.
It has to be aware that L=D*pi*N, where D is VC diameter, and N is the number of wounds IN-THE-GAP, not total number of wire-wounds on the VC,
the VC has to be the same as JBL used.
regards
ivica
It appears to me that the L variable in the BL parameter would not be possible to check visually, at least not without removing the speaker cone (which I am not keen on doing, as genuine replacement cones are now obsolete).
I can see that it is possible to get replacement accordion surrounds from Simply Speakers (I believe it was), but the spider would also need to be removed to inspect the voice coil or re-seat it in the gap. Also, I think it would be difficult (if not impossible) to remove the accordion surround and the spider without damaging the cone.
If the simple woofer swap between the two speakers does indeed show that the failure is woofer-related (which I suspect), then a used replacement woofer might be my best bet. A bit of a gamble though, I would not know for sure if the performance would match my remaining woofer 100%.
Actually it seems that SpeakerExchange have these original recone kits still available.
If I am able to scrape together some cash, I might just order one.
McKenzie also has kits with jbl cones and spiders. The voice coils are not OEM but I've compared them to OEM and there damn near the same. I went as far as measuring the width of the edge wound coil wire with calipers. Its all the same metrologically.
Nick
The price at MacKenzie recone kits is only 43% of that of the OEM one, good call. Only that it does not have the original white aquaplas coating. That is a bummer for sure.
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