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Thread: Heil with a JBL woofer

  1. #1
    Administrator Robh3606's Avatar
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    Heil with a JBL woofer

    Not sure which direction I am going to go either full up passive or an active with passive compensation on the Heil to help flatten the response. Have to be very careful with the impedance of the Heil driver combining with a passive network. Took a couple of measurements to get started of the raw driver, got an odd notch in response, repeated the measurement and it didn't go away. Have to try off axis but varying distance had no effect nor did temporarily using a baffle to keep the back-wave out of the measurement.. I did a quick 18Db network with a 5 K notch it's not bad at all. With the losses in the network it's close to the 91/92 sensitivity of either a 128H-1 or a 2214H.

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    Administrator Mr. Widget's Avatar
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    That actually looks shockingly good. I wouldn't be too worried about the narrow notch at 6800Hz. I bet it would be hard to notice it.

    I assume that is on axis. Please post more!


    Widget

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    I get the same/similar notch. This is my point where I said that you need an RTA for the best placement.

    In my system, the depth and bandwidth of the notch is directly related to where the Heil sits in relation to the 2251J cabinet that it sits on. The closer the heil is to the front of the cabinet, the deeper and tighter the notch. I get the best integration with the Heil as rearward as possible. Perhaps this is the best time alignment with the 2251, but to my eye, it looks like it would sit behind the audio plane of the 2251 in this position.

    I had attributed this to the interfacing/interference with the 2251J, but am now thinking that this has to do with a reflection, or lack thereof, from the cabinet that it is sitting on.

    BTW, Widget is correct that it is difficult to actually hear the notch. OTOH, it makes it harder to hear tones centered at the notch (e.g., some percussion). These are told by listening to other speakers with other notches/peaks (e.g., the L200/300s)


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    Very Cool!

    It's great to finally see some pro measurements of these large Heils.

    Woody's broadcast post was exceedingly attractive ( but alas, I need to sell off gear > not buy more ).

    Still, it's all a bit haunting due to long cherished memories of listening to my aunts large AMT's .

    I agree that some le14's should be a nice match-up.


  5. #5
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    OK I did some testing and included some photos. My problem is an interaction with the midrange speaker. When I turn off the midrange, the tweeter spectrum is pretty much unchanged moving from the front to the back.

    I am not getting the dip that Rob notes because I am using this in a 3-way and the tweeter is crossed over over to take advantage of this dip to produce 2nd order slope with a 1st order cap.

    Tweeter forward:



    Forward spectrum:


    Tweeter rearward:



    Rearward spectrum:


    Spectrum for the tweeter without midrange:


  6. #6
    Administrator Robh3606's Avatar
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    So today I tried an Active approach with EQ. The first was trying to use the ESS Active and it just didn't work as the slopes were too shallow. I had to add poles which I suspected it just was not worth it using the ESS I would have been better off just going passive.

    Round 2 Active was using one on my JBL M552 24dB L/R and this worked out to be the easiest solution as it was almost identical to the passive network solution with a modified lower Q notch filter.

    Hello Widget

    Yes that's on axis I will post step response and waterfall.

    Hello Earl

    I looked around for something like a CLIO measurement and didn't find one? Odd not like these are new kids on the block!

    Hello Toddalin

    Thanks for confirming the notch glad to know it's not unique too my driver. What is the resolution on the RTA are those 3db or10db notches?
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    Quote Originally Posted by Robh3606 View Post
    S

    Hello Toddalin

    Thanks for confirming the notch glad to know it's not unique too my driver. What is the resolution on the RTA are those 3db or10db notches?

    It's 2.5 dB between the dotted lines. The full scale is set at 15 dB.

  8. #8
    Administrator Robh3606's Avatar
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    Hello Earl

    Found some!

    Rob
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    Thanks Rob!

    With my high-school German being pretty rusty these days, Google Translate helped fill in the large blanks.


  10. #10
    Senior Member grumpy's Avatar
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    Indeed.

    > The original among the air-motion transformers, the AMT-1, is still being produced by ESS. The large and heavyweight tweeter is designed for free placement on a loudspeaker cabinet. Thanks to its dipole design, it radiates identically to the front and rear, thus promoting the diffuse sound in the room and, ultimately, the spaciousness in the sound image.
    Characteristic for a dipole tweeter,
    the frequency response does not shine with perfect linearity, but with an extremely broadband appearance and enormously high efficiency: 100 dB are available at 2.83 volts (equivalent to 1 watt to s ohms) if the AMT-1 at least 2,000 hertz is used. He also creates sovereign 1.000 Hertz. For this application, he is trimmed by means of a high-frequency filter to the still very respectable 95 dB available below 2,000 hertz.
    That was not always the case: in 5/2007 we tested this tweeter and diagnosed readiness at the earliest from 1.5 kilohertz. The frequency response was a bit more linear at the time, but there was a massive resonance of the membrane film at 1,000 hertz, and the distortion was a good deal higher. Obviously, almost 50 years after the invention of this tartan, ESS continues to incorporate improvements.
    Currently, the AMT-1 shines with outstanding low distortion, and the film resonance is now located a full octave lower.

  11. #11
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    Quote Originally Posted by grumpy View Post
    Indeed.

    > The original among the air-motion transformers, the AMT-1, is still being produced by ESS. The large and heavyweight tweeter is designed for free placement on a loudspeaker cabinet. Thanks to its dipole design, it radiates identically to the front and rear, thus promoting the diffuse sound in the room and, ultimately, the spaciousness in the sound image.
    No Grumpy, this is wrong.

    Just as with a cone speaker, there is a positive and negative phase and care must be used integrating the Heil with the next lower driver.

    Also, while free placement is possible, time alignment becomes very important to avoid dips/drop-outs.

  12. #12
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    Quote Originally Posted by toddalin View Post
    No Grumpy, this is wrong.

    Just as with a cone speaker, there is a positive and negative phase and care must be used integrating the Heil with the next lower driver.

    Also, while free placement is possible, time alignment becomes very important to avoid dips/drop-outs.
    Todd,

    Grumpy merely posted some of the German to English translation taken from the pdf file that Rob had previously posted.

    Clearly the Google phrase "free placement" twigged a reaction ( though I believe the phrase was merely an awkward translation for "free-standing" .

    Your concerns are all still very valid when it comes to achieving the proper integration of these units ( especially with mono-pole drivers ).

    From this pic it would appear you have some response/diffraction issues ? with your 2251 ( a somewhat similar predicament faced by Bill Shenefelt in the distant past > HERE! ;


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    Quote Originally Posted by Earl K View Post
    Todd,

    Grumpy merely posted some of the German to English translation taken from the pdf file that Rob had previously posted.

    Clearly the Google phrase "free placement" twigged a reaction ( though I believe the phrase was merely an awkward translation for "free-standing" .

    Your concerns are still very valid when it comes to achieving the proper integration of these units with mono-pole drivers.

    From this pic it would appear you have some response/diffraction issues ? with your 2251 ( a somewhat similar predicament faced by Bill Shenefelt in the distant past > HERE! ;

    I tweak these crossovers on a regular basis. Tweak, listen, listen, listen, tweak, repeat.

    Sometime the tweaks go better than others. For that photo, I had too much roll off at the top of the 2251. It has been corrected and when I get the parts soldered back (iron gave out and a new one is one the way), I'll repost. As I noted, the 2251J is not without it's "characteristics" and it takes lots of parts substitution to get them as good as they can be.

    ...But I still expect a certain amount of dip in that area.

    When I do post a video, the difference between these and the L300s is very notable, especially in the vocal range.

  14. #14
    Senior Member grumpy's Avatar
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    Lol. No worries from me. I should have been more clear that my post was simply a cut&paste job with Google Translator being the sole editor (for better or worse). Hoping to have some time with these over the upcoming holidays

  15. #15
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    For those who might be interested;

    Using RobH's Heil files ( downloaded from above ) then traced and turned into .frd + .zma files ( & then the same done to info taken from JBL's 2206H product brochure )
    here's a 1400hz crossover design that uses the mentioned drivers.

    Clearly I have taken much inspiration from Rob's previously posted hi-pass work.




    I can post the XSim file if anyone has an interest in pursuing this more seriously.


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