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Kef 105.2 Crossover / Head Assembly wiring HELP!
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Plett89
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Joined: 27 Feb 2017
Posts: 15

PostPosted: Thu Mar 02, 2017 5:01 pm    Post subject: Kef 105.2 Crossover / Head Assembly wiring HELP! Reply with quote

Hi guys
I have a nice pair of 105.2 's and is refurbishing them at the moment.
I really need som help with the wiring in this speaker.
My trouble is the six coloured wires, that goes from the xo the head unit.
I found the xo schematics online and it doesnt seem to add up with my speakers.
The schematics I found, 2nd version xo by ColinR 2004 - says that the Red and the yelow wire, is for the protection circuit - the Blue (tweeter +) the black (tweeter ) the green (midrange +) the white (midrange ).
But here is the problem, in My speakers the tweeter and midrange is sharing the black wire (tweeter ) ???
According to the schematics i have found, the white wire is supposed to be the(midrange )
It is as if the schematics is faulty, eventhough the components are the same.
SO I took my speaker cable + & directly from the amp, and placed them on the little PCB in the head unit, where the plug goes in. And the midrange will NOT play if I touch the circuit where the green and the white wire goes , but plays if I touch the black wire's circuit instead of the white's circuit.
Nothing looks tampered with in any way.
On top of the little PCB in the head unit, the blue + wire goes directly to the tweeter and the green + wire goes directly to the midrange. And a Brown wire to tweeter and a yellow wire to midrange. The two wires (Brown & yellow ), shares the same circuit on the small PCB, and in the other end of the circuit, the black wire is attached trough the plug ! !
Can someone please enlighten me, this issue takes up quite some space in my head 😊
DOES anyone have a descent and correct schematics for my speakers? Or can explane my troubles? What is the white wire for, then? A third protection circuit wire?
Maybe someone has a picture of how these six coloured wires is correctly attached to the xo PCB?
My speaker serial nr. is: 6121
And the crossover serialnr. is 11622 SP1119.

Best Regards Martin

By the way, HOW do I post pictures?
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Plett89
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PostPosted: Thu Mar 02, 2017 6:19 pm    Post subject: Reply with quote

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Plett89
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PostPosted: Thu Mar 02, 2017 6:22 pm    Post subject: Reply with quote

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Plett89
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PostPosted: Thu Mar 02, 2017 6:25 pm    Post subject: Reply with quote

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Plett89
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PostPosted: Thu Mar 02, 2017 6:27 pm    Post subject: Reply with quote

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Plett89
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PostPosted: Thu Mar 02, 2017 6:32 pm    Post subject: Reply with quote

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PostPosted: Thu Mar 02, 2017 6:38 pm    Post subject: Reply with quote

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Plett89
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PostPosted: Fri Mar 03, 2017 6:04 am    Post subject: Reply with quote

Got the pictures part 😉
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speakerguru
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PostPosted: Fri Mar 03, 2017 9:57 am    Post subject: Reply with quote

The general colour code for kef wiring of that era was
White: Input
Red: LF
Green : MF
Blue: HF
Black: normally Common/ground

In this case the red in the head will be a sensing the voltage across the Woofer for the protection circuit.

If the black is just the HF return then the yellow may be the MF return.

This is all from memory which is not getting any better Laughing
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audiolabtower
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PostPosted: Fri Mar 03, 2017 12:19 pm    Post subject: Reply with quote

In my Mk1s blue is definitely tweeter driver positive, green is mid driver positive, and naturally red/black went to the woofer terminals as Guru explains.

The tweeter and mid driver negatives were black and were naturally all common, so when I quad wired with external crossovers I identified them with blue and black and green and black markers.

The Mk1 led circuit was white positive, but your Mk2 has a more sophisticated protection so will be different.
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