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Thread: JBL 2397 Curves

  1. #1
    Administrator Mr. Widget's Avatar
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    JBL 2397 Curves

    I recently bought an electro-acoustic measurement system called Clio. I still have a lot to learn about using it to do fancier measurements like THD, Polar Plots, etc., but I have been using it to do some basic frequency plots for the Project May effort and tonight I thought I'd give it a whirl on the popular JBL 2397 "Smith" horns.

    Here is a plot of the JBL 2441 driver on the 2397 horn. The Blue plot is on axis and the Red plot is 30 degrees off axis. These plots have what is called 1/12th Octave smoothing. With smoothing it averages the response within the specified octave rate. The overall response is pretty flat (no speaker really measures flat at this resolution), and the 30 degree off axis response is surprisingly good. Realize that this horn is not really meant to be used below 800Hz.

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    Administrator Mr. Widget's Avatar
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    2397 vs. Westlake

    Here is a comparison between the JBL 2397 and one of my Westlake clones. It is interesting how the the wider lips of the Westlake do seem to improve the lower response, but at a sacrifice at the top end. This explains why I always feel the need to EQ up a bit around 6-10KHz.
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    Administrator Mr. Widget's Avatar
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    Smoooothing

    These plots are from the same measurements as above but with half octave smoothing. This is frequently the way we see response plots in catalogs as it looks better.

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  4. #4
    Steve Gonzales
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    You've got my attention!

    Lovely piece of equipment there,Sir. Very interesting data too. With all due respect, I think you should be named Mr "Wizard". I've shown the drawings to some craftsmen I know and I'll be cookin' some test runs off those drawings you so kindly posted very soon. I love this new data because I really didn't know if there was truely a difference between the 2397's and the Westlake's . Can you plot spatially or is that a bad question? Also, when you say EQing, do you use an EQ in your main system (music). I have always got such a negative response when I tell friends that I use an EQ, but to my ears, when I use the EQ, the response is pleasing . I use both parametric and fixed band- subtlely . I am curious to know if you do too and to what extent, notch filter, full fixed band or parametric?

  5. #5
    Alex Lancaster
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    Thatīs neat Widget!; Do You plan to compare the 2311/08 combo sometime?.

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    Registered User paragon's Avatar
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    Old curve

    This is measured 12 years ago by "Audio-Technik" (Lowther Dist.) with a prof.
    measure system.
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    Registered User paragon's Avatar
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    Add

    This is my 2441 with the 2397. May use this from 800-10000 Hz.

    Eckhard

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    Smoooothing ????

    Yes indeed ,

    - Nice stuff there Mr. Widget

    FWIW - For General consumption; I'd go with 1/3 octave smoothing , along with 3db vertical scale increments . The reasoning ??? It was determined decades ago, that this is the most typical change in power and/or musical division ("resolution") that the majority of the population can sense ( hence the common adoption of the 1/3 octave RTA ) . Of course everyone has different personal calibrations. For Instance : I'm quite "aware" of broadlybased level-changes as small as .5 db when implementing a balance between components .

    regards <> Earl K

  9. #9
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Steve Gonzales
    Can you plot spatially or is that a bad question? Also, when you say EQing, do you use an EQ in your main system (music).
    I do plan to do polar plots and waterfall plots at some point. I will need to get a turntable and a bit more experience using the system.

    As for EQ. I have found the White 4400 1/3 octaves to sound pretty much invisible. I have tried a variety of other EQs and felt they did more harm than good. I obviously haven't tried all of the EQs out there, only a handful really, but anecdotally there seems to be a consensus that the rotary pot Whites which have recently been discontinued are among the very best if not the very best.

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Alex Lancaster
    Thatīs neat Widget!; Do You plan to compare the 2311/08 combo sometime?.
    I don't currently have one or any 1" drivers. If someone brings one by, I'd be curious to check it out with this objective measurement gear. Subjectively, I prefer the 2397/2441. A while back I had both and did AB comparisons and to my ears there was no competition. I suppose THD measurements comparing the big 2" 2441 vs. the 1" driver should be made too as that is likely a contributing factor.

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  11. #11
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Mr. Widget
    I don't currently have one or any 1" drivers. If someone brings one by, I'd be curious to check it out with this objective measurement gear.
    Now, you KNOW I have a nasty 'ol LE85 and a "special" horn for you to test.

    Hang on. A coupla 2426's are on their way here on 2370A horns.

    I'll strike while the toys are "hot," if you'd like to check them out....

  12. #12
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Zilch
    Now, you KNOW I have a nasty 'ol LE85 and a "special" horn for you to test.

    Hang on. A coupla 2426's are on their way here on 2370A horns.

    I'll strike while the toys are "hot," if you'd like to check them out....
    To quote the fearless leader, "Bring it on."

    Widget

  13. #13
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    Quote Originally Posted by Mr. Widget
    I recently bought an electro-acoustic measurement system called Clio.
    Very exciting!

  14. #14
    RIP 2010 scott fitlin's Avatar
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    Nice!

    Impressive piece of electronics. Use it well.

    scottyj

  15. #15
    lfh
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    Thumbs up This is most interesting indeed!

    Quote Originally Posted by Mr. Widget
    I do plan to do polar plots and waterfall plots at some point.
    Thanks for posting those curves! It's most interesting to see the difference between the two flavours. I really look forward to see the polars and waterfalls later on.


    Quote Originally Posted by Alex Lancaster
    Do You plan to compare the 2311/08 combo sometime?
    As a matter of fact a 2441/2311/2308 vs 2441/2328/2397 shootout is on my to-do list, but it'll take a while since the 2308 lenses will ride in a '68 El Camino from LA to Stockholm. (Yes, I do have a pair of 2397s now - bought them yesterday! I'm sooo happy! )

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