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  1. #1
    Getting out of the Matrix Benutzerbild von Zvu
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    30.12.2017
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    Serbia - Belgrade
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    Standard Kef R300 playground - measurements of raw drivers

    I did some measurements of Kef R300 raw drivers. Rain prevented making full set of measurements but i found quiet enough neighbourhood so yesterday at about 01:00am some sweeps were heard from the parking lot.



    https://s15.postimg.cc/5exyq4gu1/image.png



    https://s15.postimg.cc/ivux8zyvd/image.png



    https://s15.postimg.cc/8lsi9rgpl/image.png


    This amount of quasi anechoic resolution makes it much easier to simulate the crossover between woofer and midrange.



    https://s15.postimg.cc/y5cvgw7l5/image.png


    I've managed to get about 9ms of gate time. I'm quite satisfied with consistency so here are files for simulators.


    https://www.dropbox.com/s/dzg8gzfclg...files.zip?dl=0


    Few words about it.


    You'll find on axis and about 45deg off axis files in .zip folder. Only woofers are merged (between 100-200Hz). Mids and tweeters aren't because there's no need to. You have everything you need to derive Z axis offset. You'll find that frequency response of midrange+tweeter, that is needed to derive Z offset between them, drops bellow 300Hz. I am protecting the tweeter that way so, when deriving Z offset, look only how combined frequency response behaves over 300Hz in regard to reference. As far as X and Y offsets all you need to know is that woofer and midrange centers are 26cm apart. There are impedance files there. Just in case you don't like how i extracted my sim files i added HolmImpulse measurements .zip file that you can import into your HolmImpulse and set the gate to derive files as you see fit.


    Here's Kef's crossover. I betcha you can do better than that if you try:



    https://s15.postimg.cc/43flgo7hn/300.png


    Measurements are done in factory cabinets, gated, at 1.03 m distance mic at tweeter axis - gate is good to 100Hz. Holm-impulse, calibrated ECM8000, M-Audio Fast Track II USB interface, Dell Inspiron notebook.


    Play and enjoy yourself (:
    Geändert von Zvu (13.07.2018 um 14:08 Uhr)

  2. #2
    Erfahrener Benutzer
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    10.01.2018
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    Excellent work, thank you very much for providing it freely!

  3. #3
    Getting out of the Matrix Benutzerbild von Zvu
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    Bitte

    It's all about the compromise on axis vs off axis. Here's my quick and dirty take on it.

    Webp.net-gifmaker.gifСкретница.png

    Phase tracking is quite good but keeping the impedance above 3 ohms while maintaining linear frequency response and good phase tracking will be quite challenging.

  4. #4
    wohnt neben dem Mühlstein Benutzerbild von bee
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    19.11.2008
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    Taunus
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    I agree, much better way to sweep the parking lot than those bloody americans with their rental Mustangs....

    In case the woofer is too loud, last resort might be to stuff the port and increase Rdc of the inductors in the low-pass until it works o.k. in that CB. May work if the woofer-TSP are so-so.
    Yes, I know, nasty....
    Viele Grüße

    Bernd

  5. #5
    Getting out of the Matrix Benutzerbild von Zvu
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    You're right on the money there. Factory coil on woofer is 2.2mH but Rdc is quite high. It is ferrite coil so maybe it is smart to change it, regardless if that Rdc suits us. I'm trying to make the crossover with as much components reused -to make it simple and less expensive- but series coil on woofer and midrange definitely should be of higher quality as should series capacitors. Those 10mH are unwinded from factory 22mH that was on woofer notch centered at 90Hz. I've kept that noch to linearize the bass but changed the values to obtain better result, in my opinion. We'll see where this ends. It'll be a journey.
    Geändert von Zvu (13.07.2018 um 20:17 Uhr)

  6. #6
    Getting out of the Matrix Benutzerbild von Zvu
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    I forgot to upload pics of impedance and woofer TS.

    Woofer impedance in cabinet:



    Midrange impedance in cabinet:



    Tweeter impedance:



    TS parameters for woofer:
    Geändert von Zvu (14.07.2018 um 16:36 Uhr)

  7. #7
    Chef Benutzer
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    18.02.2014
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    Thanks for sharing
    Viele Grüße

  8. #8
    Erfahrener Benutzer
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    01.03.2010
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    Birkenau
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    Blinzeln

    yesterday at about 01:00am some sweeps were heard from the parking lot
    You made my day
    regards Jens

  9. #9
    Getting out of the Matrix Benutzerbild von Zvu
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    @Jens

    Ich freue mich


    @Bee

    Hier ist das original schaltbild für den tieftöner frequenzweiche:

    Фабричка скрет&#10.png
    Geändert von Zvu (14.07.2018 um 20:11 Uhr)

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