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Thread: Polarity and 4343 wiring

  1. #1
    Tom Loizeaux
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    Polarity and 4343 wiring

    I've been following discussions about polarity in vintage JBL studio monitors and have been involved in discussions specifically about 4343s. Giskard sent me his opinion on correct wiring on these 4343s with the 3143 crossover. I found that I had not wired them in correct polarity and, after making the changes, found the imaging and sound stage to be vastly improved! I did reverse all wires at the drivers from JBL's original specs so these would be compatable with all my other systems, but I feel I've got these all working in phase now.
    My immediate reaction is that these 4343s sound like silk. There is no harshness, yet there is plenty of low end, ample mids, and lots of top detail. And now, instruments seem to float from between these cabinets.

    FYI JBL's spec:
    2231 green to red terminal
    2121 blk/wht to red terminal
    2420 red/wht to red terminal
    2405 gry/wht to red terminal

    Thanks again to Giskard for his help with this.

    Tom
    Last edited by Tom Loizeaux; 07-17-2003 at 04:36 PM.

  2. #2
    Senior Seņor boputnam's Avatar
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    Hey, Tom...

    A most interesting post - drawn to it like a moth to flame

    But, I'm not clear on the sequence.

    Had you reversed factory original connections and "found that you had not wired them correctly" - i.e., a simple operator error, or did it simply not sound good?

    This might get complicated, but the phrase "FYI JBL's spec" seems not right - that seems like your current configuration (rather than "spec"), in that from my reading of the schematic, you have reversed MF, HF and UHF (so they all as a group) are now phased 180-degrees from factory. They now are in-phase with the 2231H: Factory had them out-of-phase - that is LF was (-), while MF, HF, and UHF were all (+) - same configuration as the 4345 (3145).

    Your change only impacts the area of crossover (or more correctly "roll-off") overlap between the 2231H and 2121H - that is, you are now getting a doubling of those overlap frequencies, where as-factory would have cancelled those. The inter-relationships between the MF, HF and UHF are unaffected by this, and so imaging for all frequencies above the first high-pass filter should be unchanged - unless you had conflict with "incorrect" interim re-wiring, or something else in your "Tom's Wall of Sound"

    I'm intrigued with the result. Maybe Giskard's handy-dandy BassBoxPro/x-over Pro can show us what is occurring in the two different configurations? Pretty please?

    Background observation: JBL convention on earlier schematics is for each lead from the RED Input cabinet binding post to be the upper lead to each transducer**. On some, JBL labelled the (+) and (-) speaker terminals. In every case where labelled, the solid (non-striped) lead connects to the (+) transducer terminal.

    ** - except starting with the 4410 and higher, where the BLACK Input cabinet lead took top position on the transducer leads. Maybe this was timed with the beginning of the Big Change at JBL?
    Last edited by boputnam; 07-17-2003 at 09:08 AM.
    bo

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  3. #3
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    Hi Bob,

    After reading through all the earlier posts on this topic including yours from June and Giskard's from May, I called JBL and came up with:

    LF blk or grn/blk > speaker blk

    MF blk/wht > speaker blk

    HF red/wht or yel/blk > speaker blk

    UHF gry/wht or org/blk > speaker blk

    On the 3143 I looked at, the color codes were different. The speaker was purchased in 1980, the schematic on JBL's web site was 1976 so a production change must have been made.

    The above scheme would have a clear advantage to production - a red wire goes to a red terminal, a wire with black in
    it goes to a black terminal.

    The JBL engineer called a "speaker tech downstairs" for confirmation.

    JBL seemed quite proud of the fact their old equipment worked well and was still repairable. "Buy it on e-bay, send it in, and we'll fix it."

    YMMV

    John

  4. #4
    Senior Seņor boputnam's Avatar
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    Hey, John...

    The above scheme would have a clear advantage to production - a red wire goes to a red terminal, a wire with black in it goes to a black terminal.
    That was exactly my point (sometime...) yesterday. For production / assembly purposes, JBL would have:

    solid leads -> red terminal
    stripped leads -> black terminal

    This part of your post:
    LF blk or grn/blk > speaker blk
    MF blk/wht > speaker blk
    HF red/wht or yel/blk > speaker blk
    UHF gry/wht or org/blk > speaker blk
    is consistent with that.

    The connections at/from the network would handle the inter-transducer polarity/phasing configuration as engineered.
    bo

    "Indeed, not!!"

  5. #5
    Senior Member Guido's Avatar
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    Hi John!

    Right!

    I have the 4343 with "new" wiring.
    Only connect cables with black in to black speaker terminal.
    I checked what Bo wrote once and it is right, the phase turn is made internally.

    BTW if you want to reverse polarity to "non JBL terminology" then of course you have to wire cables with black in to the red speaker terminals.



  6. #6
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    Whatever...

    Wire your loudspeakers the way you want to...

  7. #7
    Senior Seņor boputnam's Avatar
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    Whatever... Wire your loudspeakers the way you want to...
    Oh come-on, please? You know this stuff backwards-and-forwards!! Did I mis-read the schematic? "Factory had them out-of-phase - that is LF was (-), while MF, HF, and UHF were all (+) - same configuration as the 4345 (3145)." No?

    I'm intrigued by your suggestion.
    bo

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  8. #8
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    I'm not saying anyone misread anything.
    If Tom wired his 4343's the way I suggested (the way the system is phased from the factory) and he likes the sound that's great.
    If anyone wants to wire them different that's great too

  9. #9
    Senior Seņor boputnam's Avatar
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    Beat me, beat me...

    ...one last time.
    the way the system is phased from the factory
    And, was that:
    LF (-)
    MF (+)
    HF (+)
    UHF (+)



    Thanks,
    bo

    "Indeed, not!!"

  10. #10
    JBL Dog
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    OMG!!

    I don't have time to tear my 4343's apart today!

    This message comes from JBL Dog

  11. #11
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    Re: Beat me, beat me...

    The RED terminal on the loudspeaker enclosure goes through the passive network to the RED terminal on the LF and to the BLACK terminals on the MF, HF, and UHF.

    It's the same with the 4345.
    Last edited by 4313B; 07-17-2003 at 02:00 PM.

  12. #12
    Senior Seņor boputnam's Avatar
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    The RED terminal on the loudspeaker enclosure goes through the passive network to the RED terminal on the LF and to the BLACK terminals on the MF, HF, and UHF.
    Thanks, very kindly, Mr. Engineer (said the geologist, none too certain about these sorts of things).

    I may have confused - I was mostly trying to understand whether them transducers were sucking or blowing. I believe, it'd be one sucking and three blowing, to use your recent metaphor

    And as always, "Cheers" to you too - but I've got three-hours and a commute to wait through first! See you on the other side...

    Last edited by boputnam; 07-17-2003 at 02:13 PM.
    bo

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  13. #13
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    Giskard,

    In your last post you said:

    "The RED terminal on the loudspeaker enclosure goes through the passive network to the RED terminal on the LF and to the BLACK terminals on the MF, HF, and UHF."

    This seems correct (!!) and agrees
    with the way I read your 5/31 post.

    This is different from Tom's post today:

    "FYI JBL's spec:
    2231 green to red terminal
    2121 blk/wht to red terminal
    2420 red/wht to red terminal
    2405 gry/wht to red terminal"

    Because the blk/wht, red/wht, and gry/wht are connected to the red cabinet terminal.

    Or I'm really missing something.

    John

    Tom's post might make sense if someone is biamping and wants a positive cabinet, but that would depend on the phase shift of the LC network which was removed by the biamp switch and I'm seriously regretting not having paid more attention in freshman physics.

  14. #14
    Senior Seņor boputnam's Avatar
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    Or I'm really missing something
    Thanks, John - me too. I felt I'm the only one in the wilderness out here.

    Tom's starting post is inconsistent with the schematic, and contrary to what Giskard finally posted.

    My head is spinning...

    But to clarify, I'm not proselytizing any one phasing over another (never meant to). I'm just trying to sort-out what JBL's original phasing was, by transducer, and it looks like:

    LF (-)
    MF (+)
    HF (+)
    UHF (+)

    based upon Giskard's last post:
    The RED terminal on the loudspeaker enclosure goes through the passive network to the RED terminal on the LF and to the BLACK terminals on the MF, HF, and UHF.
    All the involved transducers are negative, the LF Red terminal is seeing the Red Input (through the network) and so is running (-), while the MF, HF and UHF Red Terminals are all seeing Black (through the network) and so are running (+).

    But, I fear we (me...) are unintentionally pissing off a good friend, and wish it wasn't so!
    bo

    "Indeed, not!!"

  15. #15
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    I'm not sure why it is different from Tom's post.

    The following wires are "hooked" up to the RED input of the enclosure:
    Green - which goes to the RED terminal on the 2231
    Black/White - which goes to the BLACK terminal on the 2121
    Red/White - which goes to the BLACK terminal on the 2420
    Grey/White - which goes to the BLACK terminal on the 2405

    The following wires are "hooked" up to the BLACK input of the enclosure:
    Black - which goes to the BLACK terminal on the 2231
    White - which goes to the RED terminal on the 2121
    Red - which goes to the RED terminal on the 2420
    Red - which goes to the RED terminal on the 2405

    By convention, anything with a stripe in it usually gets hooked up to the BLACK terminal of the transducer. JBL has used a ton of different wire colors over the years. The "best" convention before the Ti series was green & green/black for LF, white & white/black for MF, yellow and yellow/black for HF and orange & orange/black for UHF.

    *****

    Ok, re-reading Tom's post I see the error. Tom, what was the message I sent to you? What did it say? I know what I meant but it may not have been what I said. Wasn't the 2121 out of phase or something? I purged my mailboxes so I can't go back and see.

    "Because the blk/wht, red/wht, and gry/wht are connected to the red cabinet terminal."

    Yes.

    "Or I'm really missing something."

    No. I probably am at this point....

    "This seems correct (!!) and agrees with the way I read your 5/31 post."

    Well that's a plus.
    Last edited by 4313B; 07-17-2003 at 08:40 PM.

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