How To Repair Jbl Model 4311b Control Monitors

1. But picked these up yesterday. The lpads were so bad the tweets and mids had nil output. To set up that I bypassed them. All is good now. I personally dislike lpads and prefer to featherbed them.

   Onto the issues...the "card" in the bottom is coming off. What is the all-time way to attach it back to it'southward original location ( meet pic )?

   Second problem....1 of the woofers is sticking out further than the other. It is equally though the vocalism whorl is not centered. Not certain if this is an upshot or not. Using my L100s as my basis for comparison, i of the 12s on the 4311b is further in and the other is further out ( meet the pics ).

   That said, they seem to audio fine.

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   Last edited: April 15, 2022
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2. Pics of the 4311b woofers in the resting position...note that one ( the first pic ) is college thsn the other.

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3. The woofer that sticks out, does it push in freely? I would take it out and take skilful pictures of it and mail them the real experts can give you their stance.
   Peradventure you can carefully lift the woofer cone from the back and meet if it pops back into to identify if it has not been damaged internally. Looks like information technology got a slug of ability that popped it out.

   Every bit far every bit the plate goes I would try to remove it completely with a heat gun or pilus dryer and patience then y'all can straighten information technology out carefully so glue information technology dorsum downwardly. Other wise information technology will always try to pop back upward but if you lot are going to the problem of that and then I would practise the other one and ready the crossovers. Did you lot install new LPads in place of the crossover?

   Running the mids and tweets wide open is not a good thing I bet.

4. Yep, the woofer that sticks out goes in and out freely, seems to perform fine. No voice roll rub at all. Sounds practiced likewise. Just does not wait right upon shut visual inspection. Looks like something is incorrect.

   In the past and nowadays I accept had good results bypassing lpads and using eq to fine tune the tone to sense of taste. Why would this be bad?

5. A close inspection of the spider that accompanies the mislocated woofer may plough up something. The Lpads on these Studio Monitor need to exist operational, IMO. Yous volition be trying forever to EQ out the imbalance in signal force betwixt the mid and tweeter. It may not be possible to accomplish or you may limit certain frequencies just the presentation will even so be imbalanced. It is an piece of cake job to remove the foilcal and pots, giving them a cleanup, and supersede everything in the correct order. If yous sincerely dislike Lpads, go them working, measure the resistance in the most favorable positions, and add in stock-still resistors to replace them.

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6. I had some of these for a while... great speakers! I agree that a expect at the spider is needed.

7. To respond your initial question: I e'er use contact cement to reattach labels, foilcals, etc.. Advisedly remove the piece, straighten it as best you can, apply a thin coating of contact cement to the back of the foil and to the cabinet, and stick it subsequently the glue has dried. (If the original mucilaginous stuff is lumpy, y'all volition need to remove it before proceeding to reattach the foil. Alcohol will usually remove old adhesive. Or, just roll it off with your finger. Hi tech. )

   Some people prefer two-sided carpeting tape, only I've found that the contact cement does a much better job.

   If that protruding woofer were mine, I'd leave it alone. Yeah, something is wrong. But the only real solution is likely a recone. If it sounds fine the way information technology is, I'd utilise it until repair becomes necessary. Unless you lot are obsessive-compulsive. In that case, you must repair it - at present!

   (Edit: I've read of certain JBL woofers that used cream in their magnet vents, and that foam had a tendency to decay and wander into the voice curlicue. I wonder if yours is one of them? Could the wandering cream droppings accept packed itself in behind the voice coil and is at present restricting it's rearward motion? I have no idea. I'm not a JBL owner. Simply: http://www.audioheritage.org/vbulletin/showthread.php?24338-L112-128H-woofer-vent-magnet-foam)

   GeeDeeEmm

8. I have a pair of 4311'southward, I've as well rebuilt quite a few woofers. I would like to see side by side comparison of the two woofers. The pics you took aren't that clear to me. How much is the 1 cone sticking out? It very well could be a spider issue equally has been stated. It may have go unattached from the cone. If they were overdriven and the cone came out as well far, peradventure the spider is keeping it from retracting.

9. The divergence is just a couple mm. If y'all wait at the spider from the side in one woofer, the spider is level. Y'all look at the other, it is a couple mm high in the center. I would have to take them apart again in to take pics, something I am non able to exercise at the moment. Would a detached spider upshot operation and sound? If so, how? Both woofers sound and seem to perform the same, as nigh as I can tell....null scientific involved still.

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10. Information technology wouldn't necessarily make it sound bad or even different. One trouble than could occur is if driven hard information technology might cause the voice coil to become mis aligned. If you play them and ever get a scratchy noise, turn them off immediately. When you lot get a hazard yo have them apart again just check for spider adhesion both at the bottom of the cone and to the frame. When you lot push button the cone in, it goes easily and with no noise? You should here information technology scraping on the spider if it's come up unglued at that place. Hard to say what else it could exist. But be careful not to over drive them, and enjoy them! That's the about important part

11. Definitely goes in easy with no noise. I will post pics of the spider when I get a run a risk.

12. More than pics. Note that the cone is high on the left. Spider moving-picture show is of the speaker with the high cone. JBL 2213H drivers. Aught is detached at the spider.

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13. Spider flick of the lower of the two speaker cones

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14. Look very closely at your pictures. When I enlarge them it appears quite obvious that the woofer on the left has a cone that is shaped differently from that on the correct. Information technology curves slightly earlier coming together the surroundings, while the ane on the right is perfectly flat all the way out to the environs.

    Is it possible that JBL slightly modified the cone contour over time? Or that the cone in the left speaker is adapted from another model? I'k not a JBL owner, so I don't know. But the pic makes it pretty obvious - unless in that location is some optical distortion going on.

    GeeDeeEmm

15. Mine looks more like the moving-picture show on the left! I actually think that's correct. The one on the correct is the odd ball

16. I'll bet you are right!

    GeeDeeEmm

17. I'd just buy a singleton on EBay, match two of the three and sell the oddball.

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18. If you buy one from eBay, just brand sure the white blanket is intact and in good condition

19. Can you mail one more than pic? I'd like to encounter a front view of both woofers side by side. Thanks

20. Interesting.....I did non consider that information technology could be just the design of the cone. I was led to believe that the components were all original to the cabinets and that the cabinets are but a few serial numbers off. The curve that you encounter on the left is also present on the correct hand speaker, just less visible due to the angle.....if I remember correctly, but I wasnt looking at that very closely every bit I was more concerned with the spiders. I will post more pics.

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