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Thread: Directivity and Imaging

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    Directivity and Imaging

    I've started this new thread from an OT conversation that I think deserves some discussion. I would love to see the topic expanded upon. If you've experimented with imaging please share your thoughts.


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    Quote Originally Posted by Sundown
    I've never heard the 1400 Array, so if I'm reading this right the vertical arrangement gives a taller somewhat deeper soundstage? Can you describe the horizontal effect?
    A 90x40 Constant Directivety horn has a Vertical polar pattern something resembling the following ( turn the horn sideways like the 1400 Array , this becomes the horizontal coverage ) ;



    The following is a polar pattern for some wide dispersion CD horns, (as measured in the horizontal ) .



    The first pattern exhibits a lot more "beaming" when compared to the second ( as defined by the 6db & 10db down points ) .

    One can get a very similar ( though not duplicate ) "imaging effect" by simply using the older radial type horns ( in their normal orientation, since they also "beam" ) .



    PS ; Considering the ongoing interest ( & comparisons being articulated ) between the E2 and the Array1400 , it would interesting ( & enlightening even ) to see a comparison of their respective polar responses ( Horizontal, from 1K to 10K ) .

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    Quote Originally Posted by Earl K View Post
    A 90x40 Constant Directivety horn has a Vertical polar pattern something resembling the following ( turn the horn sideways like the 1400 Array , this becomes the horizontal coverage ) ;



    The following is a polar pattern for some wide dispersion CD horns, (as measured in the horizontal ) .



    The first pattern exhibits a lot more "beaming" when compared to the second ( as defined by the 6db & 10db down points ) .

    One can get a very similar ( though not duplicate ) "imaging effect" by simply using the older radial type horns ( in their normal orientation, since they also "beam" ) .



    PS ; Considering the ongoing interest ( & comparisons being articulated ) between the E2 and the Array1400 , it would interesting ( & enlightening even ) to see a comparison of their respective polar responses ( Horizontal, from 1K to 10K ) .
    Ah gotcha!! Thanks!

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Sundown View Post
    I've never heard the 1400 Array, so if I'm reading this right the vertical arrangement gives a taller somewhat deeper soundstage? Can you describe the horizontal effect?
    No, you are taking that as a literal interpretation of the visual look of the thing. The image is deeper, but certainly not taller. JBLs have traditionally have had an "up front" sound. I and many have attributed it to a slight increase in midrange response or "presence". The L100 is classic, but most JBLs do this. However even when you equalize a JBL it will still project a forward image, perhaps less so, but it is still there.

    One anecdotal data point that I have no explanation for comes from a mod I did with fellow Forum Member Bo. We swapped out his 2421Bs from his 4345s and installed TAD TD-2002s... the system had been equalized with the JBL drivers, and was again equalized, though with less of it after the driver swap, but the image receded with the TAD. No change in dispersion (well we didn't measure it before or after so I can't be certain) but for some reason the different driver affected the staging of the sound.


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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Sundown View Post
    Ah gotcha!! Thanks!
    Really?

    I know what he is talking about, have measured a fair number of speaker systems and horns, and I don't get it from the simple dispersion plots.

    Actually, Earl... I do disagree with one of your statements, "One can get a very similar ( though not duplicate ) "imaging effect" by simply using the older radial type horns ( in their normal orientation, since they also "beam" )." I agree about radial horns and how they do beam, but if you look at the top plot you posted, while it does drop off significantly off axis, it doesn't roll off like a typical radial. The off axis response is far more linear in the vertical axis (horizontal for the 1400 Array). I think this contributes to the "natural" sound it generates, but I am not sure if it is important for the imaging. My guess is that simply reducing the amplitude of the first reflections has a lot to do with it. (Pure speculation here... but it would appear that historically everyone else's claims as to what is required for imaging is also speculation.)

    Also, I haven't found any implementation of the Altec classic radials to be stellar imaging speakers. Perhaps if the room had enough control... I've heard very narrow dispersion examples of tractrix horns image well and other multi-way otherwise excellent tractrix designs image very poorly.

    My comments and experience with the 1400 Arrays and their imaging are based on listening done in my current listening room where I have had numerous other loudspeakers from a number of brands. Most have imaged pretty well in this location as does the Everest currently, but I have preferred the imaging of the 1400 array to all of them.


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    Quote Originally Posted by Mr. Widget View Post
    Really?

    I know what he is talking about, have measured a fair number of speaker systems and horns, and I don't get it from the simple dispersion plots.

    Actually, Earl... I do disagree with one of your statements, "One can get a very similar ( though not duplicate ) "imaging effect" by simply using the older radial type horns ( in their normal orientation, since they also "beam" )." I agree about radial horns and how they do beam, but if you look at the top plot you posted, while it does drop off significantly off axis, it doesn't roll off like a typical radial. The off axis response is far more linear in the vertical axis (horizontal for the 1400 Array). I think this contributes to the "natural" sound it generates, but I am not sure if it is important for the imaging. My guess is that simply reducing the amplitude of the first reflections has a lot to do with it. (Pure speculation here... but it would appear that historically everyone else's claims as to what is required for imaging is also speculation.)

    Also, I haven't found any implementation of the Altec classic radials to be stellar imaging speakers. Perhaps if the room had enough control... I've heard very narrow dispersion examples of tractrix horns image well and other multi-way otherwise excellent tractrix designs image very poorly.

    My comments and experience with the 1400 Arrays and their imaging are based on listening done in my current listening room where I have had numerous other loudspeakers from a number of brands. Most have imaged pretty well in this location as does the Everest currently, but I have preferred the imaging of the 1400 array to all of them.


    Widget
    Yea it looks like (if I'm reading this graph right) the array horn while a little bit narrower in its dispersion pattern say maybe 60x30 displays a more controlled dispersion pattern. The wider the dispersion the greater the off axis roll off w increasing frequency, say like a 511b. To get a similar effect on an older horn (511b) you'd need to crossover sooner say at 10k.

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    If I'm going to respond ( Widget ), it'll need to be tomorrow or later ( since I'm off to work ).


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    Senior Member edgewound's Avatar
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    In my listening experiences, the speakers with the best "imaging" and spatial "soundstage" are those systems with coincident and physically aligned voice coils.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Quote Originally Posted by edgewound View Post
    In my listening experiences, the speakers with the best "imaging" and spatial "soundstage" are those systems with coincident and physically aligned voice coils.
    Can you give a couple of examples? Thanks.
    In.

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    Senior Member edgewound's Avatar
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    Quote Originally Posted by Titanium Dome View Post
    Can you give a couple of examples? Thanks.
    Sure...

    TAD Reference 1 and it's predecessor Model 1. KEF coincident speakers also by Andrew Jones. Tannoy, Altec 604, UREI/JBL.

    Soundwave Point Source 4.0. No longer in business.


    Here's some photos I just found of the Soundwave:
    http://www.bluemelon.com/tommy/veror.../photo-1854317
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Quote Originally Posted by edgewound View Post
    Sure...

    TAD Reference 1 and it's predecessor Model 1. KEF coincident speakers also by Andrew Jones. Tannoy, Altec 604, UREI/JBL.

    Soundwave Point Source 4.0. No longer in business.


    Here's some photos I just found of the Soundwave:
    http://www.bluemelon.com/tommy/veror.../photo-1854317
    Wow - those look a HECK of a lot like the DCM Time Window speakers I've seen ...

    The original DCM was bought out by another firm - tho its still in business its just a shell of the form designs ...

    Link to video the last model DCM Time Window 7 -
    https://www.youtube.com/watch?v=OnDiplqfOIE

    and an image of the original DCM Time Window from the early 80s

    Name:  TimeWindow.jpg
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    Senior Member edgewound's Avatar
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    Quote Originally Posted by hjames View Post
    Wow - those look a HECK of a lot like the DCM Time Window speakers I've seen ...

    The original DCM was bought out by another firm - tho its still in business its just a shell of the form designs ...

    Link to video the last model DCM Time Window 7 -
    https://www.youtube.com/watch?v=OnDiplqfOIE

    and an image of the original DCM Time Window from the early 80s

    Attachment 55912
    Close in looks under the skin, but the Soundwave had a much more radical frontal angle and superior drivers/geometry. The patented design was intended to address wave propagation so the cabinet would be basically acoustically invisible. It's a very stunning loudspeaker system.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by edgewound View Post
    Close in looks under the skin, but the Soundwave had a much more radical frontal angle and superior drivers/geometry. The patented design was intended to address wave propagation so the cabinet would be basically acoustically invisible. It's a very stunning loudspeaker system.
    Sure - much more upscale and a newer tech - big step since 1980 -
    I would think the Soundwave is a major evolution from that older concept...

    I've collected a number of the slightly newer DCM TimeFrame speakers -
    more of a transmision line design with inexpensive time aligned drivers ...

    And I have a lead on a pair of Vandersteen 2C speakers I need to go audition soon.
    2ch - Oppo981, JoLida502, JBL L200+, KEF 105.4
    HT7- XDA-2, BDP93, 4b NRB, B&K 5ch amp, Vandy 3A, 2Ce, VCC1, TF600 & JBL 4641

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    Quote Originally Posted by edgewound View Post
    Sure...

    TAD Reference 1 and it's predecessor Model 1. KEF coincident speakers also by Andrew Jones. Tannoy, Altec 604, UREI/JBL.

    Soundwave Point Source 4.0. No longer in business.


    Here's some photos I just found of the Soundwave:
    http://www.bluemelon.com/tommy/veror.../photo-1854317
    Those grilles look like a pair of Spandex pants. Very interesting (the design, not the pants).
    In.

  14. #14
    Obviously... not a golfer grumpy's Avatar
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    "Interested, interested, very interested, oh... not so interested" LOL...
    It's uh... uh... it's down there somewhere, let me take another look...

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    Good listen. Mr Jones goes over this very topic. I think it starts around the 10min mark


    http://www.hometheater.com/content/p...2-andrew-jones

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