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Thread: JBL 4311 behaviour: nomal or faulty units?

  1. #1
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    Question JBL 4311 behaviour: nomal or faulty units?

    Hello there,

    a first word to tell you the last mileI've done in speakers:
    I am pleased with my silky sounding B&W DM4s. Well, as a rock head I want impact and sense of life. I've been advised to try 4311.

    I'm now the owner of the serial 10027 and 10174.
    My first exeprience is terrible. Lows, not much, highs, too much, way too much, and about mids... have that feeling of phase problem, if I move my head I can quickly shift from "deaf zone" to "mids! but only one side" like a story of peak waves and cancellations.
    So my question is: can they be tricky to the point the way they are placed play that much? Do they sound that way? The fact the serial numbers are almost 150 units distant and that I've read they do changed the mids phase makes me wonder, and in my head or a real issue I d'ont know. I'm really worried in opening them, don't wan't to damage them therefore taking advices before surgery or sorrow...

    Thanks fellows,
    Matthieu

  2. #2
    Administrator Mr. Widget's Avatar
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    Unfortunately with vintage speakers it is impossible to really know if all of the parts are original or are still operating within the original specifications.

    With that in mind, I'll say that these speakers have very little bass if stand mounted in a large room... and the bass is extremely pumped up if the speakers are near room boundaries in more modest sized rooms, so placement and the room itself makes a huge difference. Regarding the high frequencies, realize the L-pads make a huge difference and need to be set properly. Due to age and not knowing if the speakers are still original and properly working I wouldn't expect the printed markings to be an accurate indication of where you will find flat response.

    Then again these speakers were never really "flat". When operating as designed they have a slightly pronounced and forward midrange.


    I hope this helps.


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    Hi,

    yes it helps, I've moved them just a bit and now their sound is better, not good but better.

    I've taken screwdriver and, holding my breath, checked the wires: at least on mids they are the same color code, had no chance to check if they were inverted at the xo. I guess they deserve a xo refresh as suggested, and later a " real " xo ( Murphy vs Troels Gravesen ). Any direction to set the 4311s according to my room's picture? It's on the long wall, the room being 20m2.

    Thanks!
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  4. #4
    Heather [Senorita member] hjames's Avatar
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    Aren't they upside down?
    I had a pair of 4312As and on mine the Woofers were closer to the floor, the tweeters up near ear level ...



    Quote Originally Posted by Malefoda View Post
    Hi,

    yes it helps, I've moved them just a bit and now their sound is better, not good but better.

    I've taken screwdriver and, holding my breath, checked the wires: at least on mids they are the same color code, had no chance to check if they were inverted at the xo. I guess they deserve a xo refresh as suggested, and later a " real " xo ( Murphy vs Troels Gravesen ). Any direction to set the 4311s according to my room's picture? It's on the long wall, the room being 20m2.

    Thanks!
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  5. #5
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by hjames View Post
    Aren't they upside down?
    Yes and no... the label is right reading in his orientation as they were designed to be placed upon the meter bridge so this orientation places the tweeters and mids near ear level when used in an old school studio. On these stands I would invert them with woofers near the floor. That said, I don't Malefoda will ever get this speaker to perform the way he wants... wrong speaker for this listener.


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    That's quite hard to read but if, playing with l-pads to get my mono records sound even and centered, so in short l-pab balanced, if I don't like them I'll will agree, not for me.

  7. #7
    Administrator Mr. Widget's Avatar
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    The L-pads are for balancing the individual speakers' tonal balance... not left-right balance. If you need to screw around with them to balance them to get a mono signal, it sounds like you might have other issues.

    Unplug one speaker and balance the other until it sounds "right". Then do the same with the other... if they end up at different sensitivities try using your preamp to balance left-right. If there is something grossly wrong with your speakers they will not balance. With old speakers having a partially defective driver is pretty common. You can look at the networks, but these speakers essentially rely on their drivers... there is almost no network at all.


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  8. #8
    Senior Member pos's Avatar
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    Quote Originally Posted by Malefoda View Post
    Lows, not much, highs, too much, way too much, and about mids... have that feeling of phase problem, if I move my head I can quickly shift from "deaf zone" to "mids!
    This is probably due to Alnico demagnetization of the woofers (they might have seen too much power at some point...).
    This affect both the sensitivity and the response of the woofers in the medium.
    You should get your woofers recharged before attempting any costly xover modification...

    Try contacting Christian from Restaur'audio in Rouen, he is probably the best specialist you could find in France to deal with your problem.

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    Junior Member fabrice11's Avatar
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    Quote Originally Posted by pos View Post
    This is probably due to Alnico demagnetization of the woofers (they might have seen too much power at some point...).
    This affect both the sensitivity and the response of the woofers in the medium.
    You should get your woofers recharged before attempting any costly xover modification...

    Try contacting Christian from Restaur'audio in Rouen, he is probably the best specialist you could find in France to deal with your problem.

    yes probably a fairly common problem demagnetization of these vintage models
    I had to problem with my pair of 4310 for all re-magnetization of alnico speakers JBL ALTEC there are also EMS speakers in Béziers (34500)
    - JBL- Westlake Audio -

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    Great... and scary at the same time,

    I still have to check phase on the woofer, but what you said makes sense as if I want a ear-matched level between the woofer and the mids I have to set mids not much than 2/3 on the 10 scale.
    Money being a factor, I'm scared shipping via La Poste heavy speakers (magnets only?) will cost me much, the remagnet itself... add that to the price of the speaker... OMG costy like a used car!

  11. #11
    Senior Member pos's Avatar
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    Those woofers are not too heavy, probably less than 6kg each, but you need special care when shipping them. Bolting them to a wood board the size of the box with rigid protective material on top should still end up under 15kg, which I think cost around 20€ to send in colissimo.

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    OMG!

    Can't wait to say it: one woofer in reverse phase!! I have the original "technical manual" and color scheme does not match, and each speakers feature different color wires... previous owners deaf? o_O
    Woofer moves forward with a tiny battery polarity test, plus on red terminal... mid moves backward... o_O' is it normal?
    At the end don't know what's in phase or not. At least the woofers were different. Quality control... not at JBL's at that time.
    ....
    some screws later..
    ....
    Having to decide which woofer is right and wich is wrongly wired, I've set both to: red-red and black-black, so if hooked a battery at the back panel they will both move forward. Did not touched the mids and even never unscrewed the highs.
    Well, like said Boston "more than a feeling", now it images nicely and the very first record I've put in get me straight into the music!
    If it sounds like a speaker is out of phase, it is. I'll keep that as true to my ears.

    Still, anyone can tell me the real deal with the mids phase reverse? From factory? Or in short any real world XO drawing anyone?

    I wonder about the previous owners...
    Thanks gents, I'll still keep the remagnet as a "to do", I'm going to discover what they sound like now!

    Matthieu
    Last edited by Malefoda; 08-18-2013 at 05:36 AM. Reason: Music after mods...

  13. #13
    Senior Member pos's Avatar
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    Problem solved!

    The black=forward is normal for JBL speakers of that era, and should still be the case at the binding posts of the speakers, so you should simply wire your woofer to get that positive black=forward behavior at the binding posts...
    If you want to use them toghether with another speaker (center channel for example) then you should reverse the polarity of course.

    Here is the technical manual with proper wiring colors:
    http://manuals.harman.com/JBL/HOM/Te...t/4311B ts.pdf

  14. #14
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by pos View Post
    If you want to use them toghether with another speaker (center channel for example) then you should reverse the polarity of course.
    Yes, and the reversal if mating to other speakers should be done at the terminal posts don't change it internally.

    Follow the wiring diagram and let us know if they've become more to your liking. Even properly working they really are great for vintage rock but not necessarily an "across the board does everything right" speaker.


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  15. #15
    Senior Member macaroonie's Avatar
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    4311 wiring diagram and schematic diagram here ......

    http://www.jblproservice.com/pdf/Stu...ries/4311B.pdf

    OOPs , same file as Pos , different location.

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