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Thread: Forgotten JBL Driver - D123

  1. #1
    RIP 2011 Zilch's Avatar
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    Forgotten JBL Driver - D123

    A driver that gets virtually no attention in the forum, what's the D123 good for besides acoustic guitar amps?

    There's plenty of them out there, reasonably priced; what do we know about them?

  2. #2
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    I never bought any while they were available in the LCS so I have no experience with them ( SURPRISE! :shock: ).

    http://www.lansingheritage.org/html/.../1976-comp.htm

    http://www.lansingheritage.org/image...comp/page3.jpg

    Also used in various 60's systems.

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    Senior Member spkrman57's Avatar
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    They are very interesting drivers.

    I have a pair along with 075's and N2400 crossover in a GE cabinet that dates back to the late 50's or early 60's.

    The sound is decent with them but the bass is light. The efficiency is around 96/97 db but not at the bottom octaves which are light up to around 80 hz.

    The usable bottom end is just below 40hz, but at a level so low that you hear all the notes in a solo, but lost when the entire orchestra kicks in.

    The cabinet is a "Distributed port reflex" system, which means the D123 and 075 are in the upper part of the front baffle and the bottom portion has around a dozen 1" holes drilled through.

    These cabinets were from back in the day when most folks bought a enclosure and just found a driver to fit the baffle cutout. Basically a general purpose cabinet.

    The pair I have are very nice to the eyes as they are detailed in the molding and looks like original grill cloth and the cabinets are made to fit in the corner as the back of the cabinet has the corner shape to it.

    I paid premium cash for them as the drivers inside are "MINT" looking and orignal and in perfect working condition.

    But the D123's are very effecient, thin in the bass and the chrome dust cap will beam above around 3 - 4 khz. I still like the simplistic design and run them once in awhile. I have several systems, so nothing stays in the center stage for very long.

    Ron

  4. #4
    Senior Member GordonW's Avatar
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    Depends on the enclosure for them... but it looks like a D123 in about 5 cubic feet with fiberglass lined walls, tuned to about 40 Hz, should solidly make it down to 40 Hz.

    Haven't measured one of them... but I suspect, as they share the cone profile of the 123A, that they MAY have a somewhat rising response in the mids (not as pronounced as say, a 2123, but a couple dB rise between 100 and 1000 Hz). This is probably what contributes to the "low bass level deficiency" thing mentioned above; this can be somewhat countered by tuning the box higher, to DELIBERATELY induce a "midbass peak" around 80 Hz, and generally raising the whole bass response output from 50-100 Hz, at the expense of a little bit of bottom end extension. In this case, maybe using a 42 or 45 Hz port frequency, might overcome the "weak bass" thing a bit...

    Otherwise, one of these D123s might make a decent midbass driver in a large three- or four-way setup... in about 1 cubic foot sealed, STUFFED with fiberglass, it has a just-under-1-dB bump in the midbass region (which could be removed by making the box say, 1.25 or 1.5 cubic feet), and is solid in both power handling and response down to about 90 Hz. In a system with a 2240 or 2245 18" woofer for the bottom, this could make a good midbass, in the sense of using it like a 2020 would normally be used. With its curvilinear cone and extended response, it would be no problem to use the D123 up to 1200 or even 1500 Hz; crossing it over to a 1" throat horn/driver midrange/tweeter setup could be quite productive of an endeavor...

    Regards,
    Gordon.

  5. #5
    Senior Member spkrman57's Avatar
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    D123 more like mini 130

    JBL literature puts the response at 45hz to 15Khz.

    But with lowered output below 80hz and beaming in the upper octaves.

    I would love to find a rear-loaded backhorn for these to fill in the lower octave response.

    The 123A is a lower efficiency driver that will give more output on the bottom ocataves. Also I believe it is around 92 db vs the D123 at around 96/97db.

    Still a nice sounding driver for low to medium listening. I use it alot for background music while working on something else.

    Ron

  6. #6
    Senior Member Don C's Avatar
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    I had a pair of very nice 123s in bookshelf cabinets, roughly the size of L-100s. The cabinets were probably not tuned well, there was just a rectangular hole cut in the baffle with no port tube. Although the condition was great, they did not sound very good. Kind of a haystack frequency response curve, Like an L-100 but with no low bass or treble. I think that I got $190. for the pair in ebay, and I don't miss them.
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    Senior Member Don C's Avatar
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    another
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    Senior Member spkrman57's Avatar
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    D123's not known for bass response.....

    More for their higher efficiency and extended HF response compared to say a 123A or 123A-1 which are more bottom octave minded.

    Ron

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    Senior Member LE15-Thumper's Avatar
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    Quote Originally Posted by Giskard
    I never bought any while they were available in the LCS so I have no experience with them ( SURPRISE! :shock: ).

    http://www.lansingheritage.org/html/.../1976-comp.htm

    http://www.lansingheritage.org/image...comp/page3.jpg

    Also used in various 60's systems.

    "in the LCS" ?????
    LE15-Thumper
    "Give me JBL, or give me death"

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  11. #11
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    LCS = Loudspeaker Component Series
    JBL was into component sales for awhile.
    Without the LCS (mid 70's to early 80's) my interest in JBL would have been compromised.

  12. #12
    Senior Member LE15-Thumper's Avatar
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    Quote Originally Posted by Giskard
    LCS = Loudspeaker Component Series
    JBL was into component sales for awhile.
    Without the LCS (mid 70's to early 80's) my interest in JBL would have been compromised.
    I thought that is what you meant. I was able to come up with a lot of Acronyms for "LCS" , I wasn't sure what yours was
    LE15-Thumper
    "Give me JBL, or give me death"

  13. #13
    Senior Member LE15-Thumper's Avatar
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    What year was that bulletin ? Amazing how James B already had the foresight to make stuff to fit at the construction level.
    LE15-Thumper
    "Give me JBL, or give me death"

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  15. #15
    Senior Member spkrman57's Avatar
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    Not only wall mounted, but reflex and horn loading...

    I would love to find a horn for mine, I see the potential they would have in a horn-loaded cabinet.

    Ron

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