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Thread: Heil with a JBL woofer

  1. #16
    Administrator Robh3606's Avatar
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    Hello Earl

    That looks good! That would be a great combo nothing like a 12 on steroids!

    Rob
    "I could be arguing in my spare time"

  2. #17
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    Quote Originally Posted by Robh3606 View Post
    Hello Earl

    That looks good! That would be a great combo nothing like a 12 on steroids!

    Rob
    Thanks Rob!


  3. #18
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    Hi Rob,

    Have you run any distortion measurements on your AMTs to see how low they can go ( before needing to be crossed out to a woofer )?

    Can they do 750-800hz ( with a 3-pole network ) ?


  4. #19
    Administrator Robh3606's Avatar
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    Hello Earl

    Not sure if I did sine or impulse will tale a look. I used the ESS schematics as a reference. They used 18 dB networks in the AMT look at the schematics posted in the General Audio Forum also take a look at the link. Either way when I rerun them I will do a sine sweep to see what's up.

    Rob

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    "I could be arguing in my spare time"

  5. #20
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    I wonder how the Heil would respond in a sealed midrange style enclosure ? ESS used to make a model 1B Bookshelf that looks interesting.

  6. #21
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    OK...I have not posted on the site very often but have been a JBL owner for years. Right now I have some 123a black cones from a L-88 and should like to try the ESS Heils as a mid-tweeter from 1200 hz. The old S70 Alpha has a crossover for the 123a that may be ok as as a start. As to your 18db for the tweeter...how was this derived as the values of components makes acquisition hard? I have no measuring equipment and generally copy others and/or use their guidance. Appreciate your input....

  7. #22
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    Quote Originally Posted by Wallacefl View Post
    OK...I have not posted on the site very often but have been a JBL owner for years. Right now I have some 123a black cones from a L-88 and should like to try the ESS Heils as a mid-tweeter from 1200 hz. The old S70 Alpha has a crossover for the 123a that may be ok as as a start. As to your 18db for the tweeter...how was this derived as the values of components makes acquisition hard? I have no measuring equipment and generally copy others and/or use their guidance. Appreciate your input....
    What's needed ( from someone owning those woofers ) is a 1 meter, on-axis response measurement ( of the JBL 123 > black cone ) working in a large enclosure ( say 4cu' ) .

    No custom crossover can be designed without employing a good response measurement ( & still be considered even half accurate ).

    Those are the hard facts.

    The HiPass can easily be 2-pole ( 12 db per octave ) with the choice of a higher crossover point ( say > 1500 hz ).

    Values ( of the passive crossover parts ) can be massaged to what's available to purchase from the regular suppliers.


  8. #23
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    Quote Originally Posted by Wallacefl View Post
    I wonder how the Heil would respond in a sealed midrange style enclosure ? ESS used to make a model 1B Bookshelf that looks interesting.
    This is a recent response measurement ( done by JavadS. ) of the big Heil ( as a monopole & also as a regular dipole )

    Name:  Javads-Heil_48277541_10217219741221259_1720178962333696000_n.jpg
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    One can see that ( with very minimal response penalty ) one could encase the back of the AMT within a mid-range enclosure ( sealed sono-tube for example ).


  9. #24
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    I've devised a "band aid" (pun intended) for the 5kHz suck-out.

    Take an engineering scale and stand it vertically with one of the three points touching the Heil right at its centerpoint on the forward face. Voila!

    Now to determine the optimum size and make a stand to make something like this work.

    Edit: Ordered a length of triangular 1" clear acrylic. This is the same dimensions of an engineering scale, though the scales do have a very specialized shape. We'll see.

  10. #25
    Administrator Robh3606's Avatar
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    Finally got a change to build up the network. I updated the network added a .33 Ohm series resistor with the inductor and changed the value to .075Mh. The added resistance altered the Q of the notch and broadened it and shifted it down a bit. It measures well in an actual vs. predicted comparison.

    Rob
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  11. #26
    Administrator Mr. Widget's Avatar
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    That is remarkably close for the predicted vs. measured!

    I donít believe in listening to speakers via YouTube and I also donít believe in listening to them via plots. That said, do they sound a bit bright? Have you had a chance to audition them?


    Widget

  12. #27
    Administrator Robh3606's Avatar
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    That is remarkably close for the predicted vs. measured!
    Hello Widget

    Well that just shows you how good that software is. I swear by it! The funny thing is every time I have had an issue its been me. So I have learned to start looking for where I screwed up if I don't get a reasonable match.


    I have not actually listened yet. I don't have any boxes built yet but I am planning on dropping one on top of one of my Array bass cabinets to see how it sounds. I don't expect it to sound bright. There is a significant drop in the top octave when you move off axis. In the vertical it is really significant as bad as the 2405 so you really need to have these at ear height. Take a look at the German magazine measurements 30 degrees off axis. I should really just do a set of off axis measurements but without the cabinets??


    If you look at the on axis for the Array its a bit hot up there. I am hoping/expecting it will work out the same way. That said I think the power response will be OK because of the roll-off but I am used to horns not di-poles so I may be in for a bit of a surprise. I expect the backwave to really open them up so to speak just like some systems with rear tweeters.

    If I get time I will try them out today or at least during the week after work. Let you know how it goes!

    Rob
    "I could be arguing in my spare time"

  13. #28
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    I, for one, would like to hear a YouTube video when done. Preferably Tin Pan Alley (Stevie Ray Vaughn) that people at AK use for demo purposes.

    I've made some recent revisions to my crossover since making this one (increased cap on Heil from 9.2 to 12 mfd to play a bit lower and decreased cap on mid from 10 to 9.2 mfd to play a bit higher), but it is not that different.

    This is the most recent video of the Ethyl Mermans and includes my wedges. Again, no sub, eq, or digital processing is used here (Pure Direct). BTW, the wedges, like my 075 slant plates, create a "semi off-axis" response on axis.

    https://youtu.be/cO8T6R2WhTE

  14. #29
    Senior Member 1audiohack's Avatar
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    Quote Originally Posted by Mr. Widget View Post
    I donít believe in listening to speakers via YouTube...
    Widget
    Yeah whatís to stop anyone from just using line out for the audio feed?

    ď! Check this out!! Single Jensen 6X9 triaxial equals JBL Everest!!Ē

    It has to be true! I saw (and heard) it on youtube.

    Also agree, nice work Rob!

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  15. #30
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    You can tell a lot from a well recorded YouTube video. You really think that Rob would do that?

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