KEF Corelli crossover rebuild SP1052 + Schematic

Discussion in 'Speakers' started by battradio, Jun 21, 2015.

  1. battradio

    battradio Electron trainer

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    Location:
    Near ST. Louis MO
    I traded for a pair of KEF Corelli speakers and got them home and they just didn't sound correct .

    http://www.audiokarma.org/forums/showthread.php?t=592200


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    And found out one of the crossovers had been replaced with the correct replacement crossover but it still didn't sound correct .

    The former owner sent me the original crossover , and the other one he purchased and learned of the melted over heated inductor L2 on each crossover .

    I replaced the caps on the two Crossover boards with the good inductors , measured all three on each board with a Meterman LCR555 and drew out the schematic

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    The over heated inductors had changed value from 2.1 Mh to .375 Mh on one and .265 Mh on the other .

    Having the bad crossovers i decided to repair them also by winding new inductors .My first try was made from the barrel of an ink pen and gator aide caps .

    Went to the local ACE hardware and purchased nylon washers and spacers and glued them together to make bobbins with gorilla glue

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    You can see that the insulation came off of the wire due to the heat

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    The orange bobbin was the prototype , the two larger ones use larger wire gauge , but have the same inductance ,that i will keep for spares .

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    The totally rebuilt crossovers . The original 30 uf 50 volt caps were tiny compared to the other caps on the board and must have had a terrible power factor and ESR compare to the other caps used .


    The only schematic i could find on line was totally wrong for these speakers so i want the part number in the title so if someone else does a search it will pop up .

    Will most likely make a pair of speakers with these crossovers if i can find a suitable tweeter .

    The Corelli's are now a joy to listen to .:music::music::banana:
     
    leesonic likes this.

     

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  2. Lavane

    Lavane AK Subscriber Subscriber

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    Nice work Mark! :thmbsp:
     
  3. tyella

    tyella AK Subscriber Subscriber

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    Holy cow! Well done, sir. Those speakers found the right home for certain!
     
  4. leray1

    leray1 AK Subscriber Subscriber

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    I've got Corellis but they're the SP 1051 Type. What's the difference?
     
  5. battradio

    battradio Electron trainer

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    5,171
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    Last edited: Jun 23, 2015
  6. toxcrusadr

    toxcrusadr Omelette au Fromage Subscriber

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    Just ran across this thread, well done! This is why I keep every inductor and discarded junk crossover I run across, in case I ever need one. I have about a dozen pairs so next time you need one let me know, I might have it. In any case the tutorial on DIY inductors is great.
     

     

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  7. leesonic

    leesonic Hold on, here comes the bass. Subscriber

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    Nice work rewiring the inductors. I'll have to remember that tip using the nylon washers.

    Lee.
     
  8. battradio

    battradio Electron trainer

    Messages:
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    Location:
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    Thanks for the nice comments , these speakers sound immensely better than when i got them all the work was worth it .

    Mark
     
  9. spkrdtr

    spkrdtr spkrfixer

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    Rewinding inductors. Now that's dedication and persistance. Good job :thumbsup:
     
  10. custino

    custino New Member

    Messages:
    1
    date of 2015 but I think L2 is not 2.1mh, but 0.8 mh maximum. it have not ferrit and with a little calcul, with dimensions, winding number and all the will of the world, L2 can't be a 2mh.
    how did you mesure it ? on the pic your two L2 are out of service. So what inductance did you mesure ?


    https://www.carnets-tsf.fr/inductance/calculateur.html


    and be careful, L3 = 0,3mh... not 3mh


    EDIT : ok I re checked winding number, and I was too just. possibly L2 is really 2 mh.

    it should be same crossover than in the corelli, dn17 version, picture in this thread, second post :

    https://www.ls3-5a-forum.com/viewtopic.php?f=21&t=7811&mobile=on
    resistances in serie on self are resistance of the self.

    too bad wire gauge of all these tiny kef coil are too little.
    maybe a solution, to improve it : replace self by same value but more big wire, and make the complement value resistance of original self with a resistance.
     
    Last edited: Oct 8, 2018

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