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Thread: 1,5" wave guide shoot-out

  1. #1
    Member sebackman's Avatar
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    1,5" wave guide shoot-out

    I'm going to do a measuring run on JBL M2, 4367 and VTX waveguides the next few days.

    I will try a few different dia's in 2450SL, and 2451 cores. I'don't have an Mg dia and not sure it will take apart my other system to get to the Be's.

    I will prost some findings here and if someone want the raw data just give me a shout.

    Kind regards
    //Rob
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    The solution to the problem changes the problem.
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  2. #2
    Administrator Mr. Widget's Avatar
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    Very cool... looking forward to your discoveries.


    Widget

  3. #3
    Senior Member 1audiohack's Avatar
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    Hello Rob;

    Is the little horn a 5006815?

    I just bought a couple of these to try for a high SPL super tweeter for use from about 5kHz and up. I am looking for something that screams at least to 15kHz to augment the 2451SL’s on 4338 horns. I was hoping to use D2’s on them but the PWT measurements I took last weekend show the D2 performs much like a regular compression driver in that it is about 26dB down at 15kHz from its peak.

    What are you specifically looking for? I am interested for sure. I have never had the 4367’s horns at my disposal.

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

  4. #4
    Member sebackman's Avatar
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    Yes the small ones are #6815 from VTX F15/F12.

    My plan is to do a run with 2450SL, 2451SL, 2451/475Nd, 2451Ti and D2's on all WG's. I don't have access to an Mg driver and not sure I will take apart my main system to get to the Be's.

    I use MLS pulses as they are rather noise resistant and will record gated runs with 3ms, 6ms, 9ms time window from about 4-500HZ (no smoothing, that can be applied later) at both 50cm and about 100cm distance.

    I hope to do 90, 60 30 degrees on the 6ms runs.

    That will be quite a numer of measurements on that many driver pairs. I will run a Focusrite III USB card and do 2 channel measures where the amp signal (Alesis RA300) is subtracted for better resolution. The mike is the usual Earthworks M30. I will not apply any XO, just a capacitor in series for protection and run at maybe 80-85db max.

    I will also try run impedance runs for all driver/WG combinations with a DATS3 box.

    I hope that would give sufficient data to see what is the room and what is driver/WG and how the 4367 fairs against the M2. I hope the 4367 could be a good choice as the M2 is really 100x100 degrees which is fine in a dampened studio environment but may require some adjustments at home.

    I have a space in the workshop where I can apply 8cm egg crate padding to all walls which should help. It's cold over here right now so no possibility to go outside.

    This is to decide what route to go with my DSP active 4367M clones that will use a 2451 core instead of the D2's. Unless this shoot-out shows that the D2's are indeed superior on the 4367 WG.

    Barry, we routinely use 2450SL or 2451SL on the little #6815 in our two way systems. Albeit they are DSP systems but we use the combo from about 1kHz to 20kHz without any problem. Normally we use a 2206 or a PRO1400 under the horn/WG + a sub.

    I also have a system with the same combo and a 2217 which also works fine and does provide bass to be used as party speakers without sub. PM email address and I can send some measures.

    All input much welcome on changes to the plan or additional thing to check out.

    Kind regards
    //Rob
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  5. #5
    Member sebackman's Avatar
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    Here is the driver lineup. :-)
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    The solution to the problem changes the problem.
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  6. #6
    Administrator Mr. Widget's Avatar
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    Oh boy!

    And oh boy do you have your work cut out for you!!!


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  7. #7
    Administrator Robh3606's Avatar
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    Hello Rob

    "I hope to do 90, 60 30 degrees on the 6ms runs."

    Just a suggestion but I would add a 15 degree measurement as well. Figure the listening window should be between 0 and 30 and it wouldn't hurt to have a look in the middle so to speak. Just to see how much variation there is between the 3 measurements. You could also average them to see what the "window" curve looks like.

    You certainly do have your work cut out!

    Have fun Rob
    "I could be arguing in my spare time"

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    Senior Member srm51555's Avatar
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    This is going to be fun and exciting! Thanks Rob

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    Senior Member JuniorJBL's Avatar
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    Looking forward to your observations Rob!! Thanks!
    Always fun learning more.......

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    Thank you for doing this and I hope I can follow along.I have to ask though, what is a 2451Ti?special diaphragm?

  11. #11
    Member Mitchco's Avatar
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    Very cool! Looking forward to your data. Are all the waveguides constant directivity? Any thoughts on accounting for constant directivity eq or is it not applicable for your scenario? https://sound-au.com/project173.htm Btw,I am a huge fan of JBL CD's and waveguides. I use the 2384 waveguide with 2453h-SL cd. I really like the sound of the large format JBL cd's. And the Aquaplas coating smooths out the response. But i have been eyeing the M2 and 4367 waveguides for sometime as the 2384 is a little too narrow in directivity. So, I am very curious to see and hear about your results. Thank you for doing this!

  12. #12
    Member sebackman's Avatar
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    Getting there

    Busy day with about 200 measurements done. All impedance measures done and all 50cm measures done.

    Tomorrow I will do 100cm measures to compare. Annother 160 or so.....

    4367 does load the drivers deeper than M2 and 4" does provide better coverage than D2 below 1kHz. But we guessed that, now we know.

    M2 is smoother of axis comp to 4367 and VTX. Maybe 50cm is just to short for the 4367 off axis, I will see tomorrow.

    More data tomorrow.

    Rock on
    //Rob
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  13. #13
    Member sebackman's Avatar
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    Now, what do we want to know?

    I have now completed the measurements and albeit not the same quality as anechoic they do give a reasonable picture of the various JBL 1,5" drivers on the VTX, M2 and 4367 WG's, on and off axis. At least the settings (HW/SW/room/settings/timing/temperature) are identical in all measures, which makes them direct comparable.

    The result is about 400 measurement files at 50cm and 100cm distance for 30, 60 and 90 degrees. The files are done without any smoothing and include phase. I did do 3ms, 6ms and 9ms time windows for all combinations to make sure that I got reasonable low end data with a long window but also a short window to see the high frequency with limited room intervention. I used pairs of 2450SL, 2451SL, 2451&475Nd, 2430K and 2451h (Ti, only one). 9 drivers all in all.

    I have long argued that the 4" drivers do sound good on these WG's and numbers seem to support that. Please bear in mind that these are raw files and would look significant "nicer" with some smoothing, as most (also JBL) manufacturers show them. It is also clear that 4" goes lower than D2 in these WG's and that 4367 provides horn load to a lower frequency that M2. M2 sure is nice off axis. Horizontal and vertical dispersion is NOT the same in the M2 as could be anticipated from looking at it.

    Below are some graphs. You can see measurement data (distance, time window aso) in the graphs. SW is LspCAD 6 PRO with MLS pulses at max resolution. HW computer + Focusrite SOLO V3 soundcard, Earthworks M30 mic, and an Alesis RA300 studio power amp. All walls (and ceiling) had at least 8cm thick sound padding (with egg crate surface absorbers). Measures are 2-channel, meaning that one channel measures the power amp out and second channel the mic and we only project the delta. No capacitor, only a protection resistor in series, so phase is not tuned 90 degrees as in many other measures with protection cap.

    Kind regards
    //Rob
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    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  14. #14
    Administrator Mr. Widget's Avatar
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    Lots to absorb there… thanks for sharing!


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  15. #15
    Senior Member 1audiohack's Avatar
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    Hello Rob;

    I don’t have the 4367 but have everything else you have tested and your findings mirror mine.

    Thank you for showing the phase response as well. That is one solid key to establishing a drivers truly linear usable range.

    Thank you for taking the time to post and share all of this.

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

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