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Thread: JBL 4311B Control Monitor Polarity Confusion

  1. #16
    Administrator Robh3606's Avatar
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    Did ANYONE even look at the JBL Proservice pdf I linked? The answer is plain as day on the wiring diagram on it!
    Yes and I suggest you look at it again because you got it wrong

    Rob
    "I could be arguing in my spare time"

  2. #17
    Senior Member SEAWOLF97's Avatar
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    Not to stir things up , but ...

    is it not possible to just put a multi-meter on the drivers leads and see which way produces positive results when signal is applied
    “If you think that’s the dumbest thing you’ve ever heard,
    just wait a couple minutes!”

  3. #18
    Senior Member RMC's Avatar
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    RE post # 12: "I found a JBL's 'Technical Notes, Volume 1 Number 12' document I found on Polarity (I tried to attach it). It's dumbfounding how they do not mention the 4311B monitors,"

    Look at the following pic, items 1 & 2 in the first group and item 5 in the second group, it may help clarify this matter and others... Regards,

    Richard


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  4. #19
    Administrator Robh3606's Avatar
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    Not to stir things up , but ...

    is it not possible to just put a multi-meter on the drivers leads and see which way produces positive results when signal is applied
    Sure the 4311/4312 have the woofers running fullrange. You could do the battery test. The caps will protect the midrange and the tweeter from DC. They should have standard polarity when wired correctly.

    Rob
    "I could be arguing in my spare time"

  5. #20
    Senior Member DavidF's Avatar
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    Quote Originally Posted by short_circutz2 View Post
    Did ANYONE even look at the JBL Proservice pdf I linked? The answer is plain as day on the wiring diagram on it!
    Yes, but you are misreading the intent of the symbols, I believe.

    The driver "+" and "-" are the driver input and return terminals, respectively, not representing positive or negative polarity of the driver.

    Systems of this vintage used a convention of wiring coming out of the network that had the solid colored wire attached to the driver input, regardless of the whether the signal it carried was signal in or signal return. The black or striped wire was attached to the driver return terminal.

    For this 4311B the signal coming in from the amp is carried through the red "+" input on the enclosure input terminal and then passed through to the woofer return "-" terminal (black) by way of the green/black wire coming out of the network.

    So, if you are trying to confirm whether the system is wired correctly, just follow the convention that has the solid network wires hook up to the driver input, "+" or red, and the striped wire to the return, or black. Some mids and tweeters used quick-connect terminals that could only be connected one way.
    David F
    San Jose

  6. #21
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    Quote Originally Posted by Thrifty HiFi View Post
    I was able to find this attached schematic for the L100, Century/4311 which tells me the "Male terminal is PLUS" on a LE25/26. Fingers crossed it is the same for the LE25-4 (not too confident in that actually, but that's all I got).

    I needed to know this because the original disconnects were cut off to solder on the Audax tweeter, and I'm about to install new disconnects on the yellow wires to hook up one of the LE25-4.



    Attachment 84301

    Hello again. Sorry for disappearing for a while. It's summer, and well... not much time to fiddle around.

    So this schematic I posted, led me to hookup a female connector to the yellow wire, and put it on the male terminal on the LE25-4 (and yellow-black to the female on the LE25-4). I did this to one speaker, assembled it, and compared it to the Audax. The result was what I was hoping for I guess. The LE25-4 was way more crisp and had more volume.

    And that's where I got distracted and put this whole thing aside.

    To get myself in the mood, I was looking online at refinished JBL monitors. The I stumbled upon this from a post by JeffW back in 2017:

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    I thought... this is exactly what I was looking for... except not what I did. So If both are right, I guess the yellow/black needs to go to the male terminal (Plus).

    So does this make sense? Are the woofer and midrange in phase with each other, and the tweeter is out of phase?

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