Kef R105/3 Kube equaliser schematic

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J

jez

Member
2004-01-01 3:16 pm
n.e england
  • #1
    Having recently aquired a set of Kef Reference series 105/3 speakers (see my recent other posting on the subject....) I would like to try them with the Kube equaliser, I believe it is the Kube 200 that is the one for this speaker but I'm not too sure. I would prefer to build one rather than buy one so.....has anyone got a circuit diagram?. I have done a search and found that a site member called AndrewJ says that he used to work for KEF and that he designed it....Do you have a circuit Andrew?
    Thanks in advance for any help:)
    Jez.
     
    A

    AndrewJ

    Member
    2001-09-05 6:37 pm
  • #2
    Hi Jez,

    Yes I did work for KEF, from '83 to '94, and I designed all the Kubes.
    I still have a Kube 200 tucked away somwhere.
    I am not so sure whether I have the circuit diagrams, but I could with some effort reverse engineer it if I can find my sample.
    Basically all I need is to work out the Q an Fo for speaker in order to re-design the circuit.
    Let me look around and see what I can come up with, but life is hectic at the moment getting ready for CEDIA, so it may take a while.

    You may have to give me a prod to remind me!

    Andrew
     
    J

    jez

    Member
    2004-01-01 3:16 pm
    n.e england
  • #3
    Hi Andrew,
    I have since been in touch with KEF by telephone and they have told me that they would be willing to let me have a circuit diagram for the Kube 200 (surprisingly!), however I have still not heard back from them (I was told they would have to find it first and that it could take some time...).
    Thanks for your offer of help, but for both our sakes I think it wise to let KEF have a bit more time to find it, I'd hate for you to go to the lengths of reverse engineering it and for a copy to arrive from KEF the next day!
    BTW, how do you rate the 105/3?, the bloke I spoke to at KEF seemed to think that it was the best speaker they have ever made!?
    Cheers,
    Jez.
     
    A

    AndrewJ

    Member
    2001-09-05 6:37 pm
  • #4
    Jez,
    I hope that KEF do find the cct diagram for you.

    The 105/3 was one of the best speakers that KEF designed. It was the last model designed by the chief engineer that preceeded me.

    Continue enjoying it, and let me know how you get on with building your own Kube.

    Regards

    Andrew
     
    J

    jez

    Member
    2004-01-01 3:16 pm
    n.e england
  • #6
    Andrew,
    Kef are now telling me that they don't in fact have a diagram for the kube and that it was not designed by them but by Meridian....
    I don't believe them....can't be bothered to look for it more like!
    Any how, would you want to sell your KUBE 200?, or better still, if I was to pay all postage costs, could I borrow it so that I can reverse engineer it?
    Jez.
     
    J

    jez

    Member
    2004-01-01 3:16 pm
    n.e england
  • #8
    It may well be a Linkwitz transform but then again there may be more to it than that, it may mess with the overall Q of the system for example. Too many unknowns for to try and design one from scratch (unless I knew exactly what it's tranfer function was, accurately and in detail)
    I'll give Meridian a ring just for a laugh:whazzat: probably get some oik saying "KEF? never 'erd of em.."
    Jez.
     
    A

    AndrewJ

    Member
    2001-09-05 6:37 pm
  • #9
    Hi hkvictorhui,

    I can get the pin configuration fairly easily, but this week I am at CEDIA, so you will have to give me time until I get back to get the info.

    Jez,
    Whoever you spoke to who said that it was designed by Meridian was clearly mistaken. Probably the confusion arose because at the time that KEF was manufacturing the KUBE, we had a financial interest in Meridian.
    However I can assure you that their engineers had no involvement in the design.
    I will see if I can call KEF to track down the cct, and if not I will dig out mine from storage.

    Regards

    Andrew
     
    Kravchenko_Audio

    Kravchenko_Audio

    Member
    Paid Member
    2002-01-19 2:56 am
    Perth Canada
    www.kravchenko-audio.com
  • #12
    A

    AndrewJ

    Member
    2001-09-05 6:37 pm
  • #15
    Hi hkvictorhui,

    I'm back from CEDIA and have just found my Kube 200.

    The pin configuration and transformer requirements for the AC input is:
    Transformer: two secondaries, each 23Vac no load or 46Vac center tapped
    power supply plug: 5pin DIN 270deg. Center pin is common
    Pins closest to center pin on each side is unused
    Pins outermost are the AC voltage.

    So, each winding is connected between one outer pin and the center pin.

    Is this clear the way I have explained it??

    Jez,

    Are you still in need of the cct diagram?


    regards

    Andrew
     
    H

    hkvictorhui

    Member
    2005-09-02 7:48 pm
  • #18
    Dear Andrew,
    Thanks a lot for your help. I think I can understand the pins assignment but what is the rating of the supply please?

    Besides, could you please also advise the connection diagram of the Kube 200 to the speakers or do you have the idea of where can I find the user manual?

    Regards,
    Victor
     
    H

    hkvictorhui

    Member
    2005-09-02 7:48 pm
  • #19
    More technical information on the Kube 200 supply please

    Andrew,
    There are more technical questions in constructing the supply:
    1) Can the transformer be 24v-0-24v as there is no 23v-0-23v transformer readily available in the shop?
    2) What fuse rating should I use for the protection?
    3) Repeated from my previous posting, what VA should the transformer be?

    Thanks
    Victor
     
    A

    AndrewJ

    Member
    2001-09-05 6:37 pm
  • #20
    hkvictorhui,

    Yes the power supply can be 24-0-24v. It is regulated down to +/-18v in the regulators.
    The VA rating of the supply shouldn't be crtical, anything of around 5-10VA should be fine.
    As for fusing, we never fused the originals, but you could perhaps try something in the range of 200mA fuses as a precaution, but just be careful about the inrush current and use slow blow fuses.

    The Kube is connetced in the tape monitor loop of the pre-amp, or between the pre-amp and power amp. Input and output are on RCA connectors.

    I am working on the cct diagram, squinting my eyes and trying to dredge the memory banks to remember the topology I used. My eyesight isn't what it used to be when I first designed it!!

    Regads

    Andrew
     
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