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Thread: 2115/le8t/2108

  1. #1
    Senior Member bldozier's Avatar
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    2115/le8t/2108

    Hi,

    can someone one provide a chart comparing the 3
    mentioned 8" drivers. I'am looking for one more
    2108, which I may or may not find.
    Iam looking for a temporary substitute for
    the missing driver for now.

    I understand that the aquplasless 2115 may
    play higher then the le8t without the cone
    coating the chart dictates a significant
    dropoff of the le8t @ around 500khz while the 2108 is
    steady. Maybe a mass ring can be added to
    extended the range down low of the 2115.
    Does the le8t use a mass ring?
    Name:  IMG_0192.JPG
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  2. #2
    Senior Member bldozier's Avatar
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    Does the grap provided too much of a disparaging
    curve for the tandem to be used together
    temporarily?

    Can an someone provide a graph of the
    112 an 2108

  3. #3
    Senior Member Flodstroem's Avatar
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    Quote Originally Posted by bldozier View Post
    Hi, Does the le8t use a mass ring?
    No, only Aquaplas
    Flodstroem

  4. #4
    Senior Member bldozier's Avatar
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    Ok thank you flodstroem... I thought not
    but read somewheres they do...
    so how would I go about creating a comparison
    chart for all 4 drivers.

  5. #5
    Senior Member Flodstroem's Avatar
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    An alternative could be to purchase a temporary substitute for the 2108 like this model (and it looks to be cheap) if it still has the full SPL and frequency response
    Later you could always sell them or keep them for another speaker project
    http://www.ebay.com/itm/JBL-2118H-8-...wAAOSw2xRYm2F-
    Flodstroem

  6. #6
    Senior Member bldozier's Avatar
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    I've decided against using 2118s. Just looking for
    a comparison of the above mentioned
    drivers

  7. #7
    Senior Member bldozier's Avatar
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    Anyone

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    Quote Originally Posted by bldozier View Post
    I've decided against using 2118s. Just looking for
    a comparison of the above mentioned
    drivers
    Anyone (?)
    Brian,

    You should take Flodstroems advice and buy a pair of good used 2118h(s) as standins while you wait to obtain another 2108 .

    The 2118 is a good speaker, which is why it was used as the basis for the 108H ( > used in the much loved 250ti series of speakers ) .

    ( As requested & fwiw ), here's a comparison made of the 2115 vs the le8t vs the 2108 ( using your Japanese source for my basic trace info ) .
    - From the traces seen, the 2115 doesn't look very usable in my opinion ( > when using a standard 4315 network ).
    - Now, that's only "if this Japanese trace can be believed" ( which is in some doubt ).

    FYI, relative levels for the 3 are not correct because the Japanese originator of the files referenced all his captures to a single 1K point ( instead of referencing to a constant voltage ).
    - As an example, I would expect that the 2115 should be more efficient than the le8T in the mid-band area above 200hz ( but here it's not ).


    What I've shown is only relevant to get an idea of the various response curves ( but not absolute levels ) & even these 3 responses are quite suspect since I notice his graphs all have a common midband suck-out ( 400-900 hz ) for one reason or another ( I suppose it's a measuring anomaly ) .

    Name:  JBL_comparisons of 3 eights.png
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    PS: my vertical scale is purposefully somewhat "Hi-Rez" ( so as to hi-light the differences ) .

  9. #9
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    The software used to capture these traces ( which happens one at a time ) is called FPGraphTracer ( available for Windows & Mac ).

    Each graph was then saved as a .frd file .

    Each frd file was then imported into REW for display and posting purposes ( REW is available for both Windows & Mac ) .

    I find this ray tracer works best on color traces ( in fact, I've never successfully captured a trace that was similar in color to the grid pattern ).
    - OTOH, used on a color trace, it's very good and dead simple to use.


  10. #10
    Senior Member Flodstroem's Avatar
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    Quote Originally Posted by Earl K View Post
    The software used to capture these traces ( which happens one at a time ) is called FPGraphTracer ( available for Windows & Mac ).

    Each graph was then saved as a .frd file .

    Each frd file was then imported into REW for display and posting purposes ( REW is available for both Windows & Mac ) .

    I find this ray tracer works best on color traces ( in fact, I've never successfully captured a trace that was similar in color to the grid pattern ).
    - OTOH, used on a color trace, it's very good and dead simple to use.

    Thanks Earl for the interesting hints and info.
    Flodstroem

  11. #11
    Senior Member bldozier's Avatar
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    Yea thank you. Mr. K.

  12. #12
    Senior Member bldozier's Avatar
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    Quote Originally Posted by Earl K View Post
    Brian,

    You should take Flodstroems advice and buy a pair of good used 2118h(s) as standins while you wait to obtain another 2108 .

    The 2118 is a good speaker, which is why it was used as the basis for the 108H ( > used in the much loved 250ti series of speakers ) .

    ( As requested & fwiw ), here's a comparison made of the 2115 vs the le8t vs the 2108 ( using your Japanese source for my basic trace info ) .
    - From the traces seen, the 2115 doesn't look very usable in my opinion ( > when using a standard 4315 network ).
    - Now, that's only "if this Japanese trace can be believed" ( which is in some doubt ).

    FYI, relative levels for the 3 are not correct because the Japanese originator of the files referenced all his captures to a single 1K point ( instead of referencing to a constant voltage ).
    - As an example, I would expect that the 2115 should be more efficient than the le8T in the mid-band area above 200hz ( but here it's not ).


    What I've shown is only relevant to get an idea of the various response curves ( but not absolute levels ) & even these 3 responses are quite suspect since I notice his graphs all have a common midband suck-out ( 400-900 hz ) for one reason or another ( I suppose it's a measuring anomaly ) .

    Name:  JBL_comparisons of 3 eights.png
Views: 287
Size:  49.4 KB



    PS: my vertical scale is purposefully somewhat "Hi-Rez" ( so as to hi-light the differences ) .
    I wonder if the demagnization of the alnico
    motor affects response of the le8t above the mentioned
    200hz. Maybe a ferrite motor maybe best used as a companion
    speaker to the 2108 or bi amping

  13. #13
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    Quote Originally Posted by bldozier View Post
    I wonder if the demagnization of the alnico
    motor affects response of the le8t above the mentioned
    200hz. Maybe a ferrite motor maybe best used as a companion
    speaker to the 2108 or bi amping
    Alnico demagging will manifest itself in at least 2 visible ways ( when viewing the FR ).

    One; the bass can bloom a bit ( maybe by a couple of db ) due to less magnetic control ( damping ) on the cone/coil assembly from the magnet.

    Two; the mid to high-mid comes down a couple of db.

    200hz?? I can't really tell you off-hand what the Fs tipping-point is ( think in terms of the fulcrum of a teeter-tooter having a frequency ) .

    The trace of the le8t I displayed looks like it might be the result of a bit of demagging > ( it has LF bloom & some loss of midrange linearity ).

    OTOH, the thing is, that trace comes from the blog of a very fastidious speaker repair-man ( a real craftsman ) that seems to check every repair for linearity, ( sometimes gauss levels in the gap ) as well as a check for distortion products // so that all suggests I might be wrong in my own ( seat-of-the-pants ) assessment .


  14. #14
    Senior Member bldozier's Avatar
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    It is a 2" am 3" arrangement, being compared.
    Maybe one day you mr k can add the 2118 an 112
    into that fray... the 2118 being 2" vc as well.

  15. #15
    Senior Member Flodstroem's Avatar
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    If looking at the Bl product the compared speaker are far from each other LE8T/2115 has only a Bl of 6.2/6.8 compared to the 112A (Bl=12) and the 2108 (Bl = 13)
    The 2118H looks more to be equal to the 112A though it has a Bl of 11. Thats why I recommended the 2118 but also because of the fair price of a decent pair
    Flodstroem

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