KEF 104B crossover schematic needed ! - diyAudio
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Old 7th August 2002, 08:13 AM   #1
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Default KEF 104B crossover schematic needed !

Hello everybody,

I want to find some construction information on the KEF 104B speaker.
This speaker was a 2 way design that used a T33, a B200 and a 139B passive radiator. I need the box dimensions and the crossover for this speaker.

Thanks a lot in advance.

Greetings Ilias
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Old 7th August 2002, 08:51 AM   #2
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The tweeter I think should be a T27. I am not 100% sure.
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Old 12th August 2002, 05:08 PM   #3
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Default kef 104

Hi i have a pair of kef 104 speakers they use a B200 BD139 passive radiator and a T27 tweeter i have the crossover design + i know the guy that was on the design team at kef in the 1970s
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Old 10th September 2003, 08:22 PM   #4
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measured values for L from early 104aB

dave
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Old 10th September 2003, 09:10 PM   #5
qwad is offline qwad  Australia
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I really wish I could help you right now, but it was in a book had and sold on ebay last year by MARTIN COLLOMS, called "high performance loudspeakers" perhaps a library near you may have it on it's shelves.... etc, etc, hope you find it as the 104 ab x, over as well as the spendor bc1 and 111 are also featured in there... cheers and best regards TC
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Old 11th September 2003, 09:29 PM   #6
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I happen to have analysed the 104aB filter as a start of my 'career'. The LF filter is simple and consists of a 3rd order filter with a resistor parallel to the second inductor. The values are:
L1: 2.7 mH switchable to 3.6 and 2.0
L2: 500 uH (with 10 ohm parllel)
C1: 5 uF

The HF filter is as shown above. with the following values:
C1: 3.3 uF
C2: 10 uF
C3: 10 uF
C4 (the one pareallel to C1 and C2): 600 nF
R1 (parallel to C3): 3 ohm
L1: 2.4 mH

The inductors where rather high resistance iron core ones. It seems that the speaker doesn't improve with better components but I never tried that. Theh capacitors I could not identify but where not much better I suppose.

The tweeter is indeed a T27. I'm not sure as to the B200 and the size of the cabinet. I sold mine some time ago.
By the way. The acoustic responses weren't that good. The B200 has some nasty break up frequencies.

Good luck.
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Old 12th September 2003, 02:24 AM   #7
qwad is offline qwad  Australia
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Yes DICK, you are right on the money as far as the B200 is concerned I know the early MONITOR AUDIO MA 4used it [ btw designed by the same erstwhile audio journalist; MARTIN COLLOMS ] who wrote the book I mentioned above in my prev post] using this driver had to be heavily equalised in a similar fashion because of this.... probably the same reason he did not use the venerable and much over rated T27, Choosing the isophon kk 8 or was it 10? in this design instead: and BTW the 104 ab used the T27, for sure regards to all TC
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Old 19th November 2008, 11:59 PM   #8
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Default Re: kef 104

Quote:
Originally posted by ANTHONY2181
Hi i have a pair of kef 104 speakers they use a B200 BD139 passive radiator and a T27 tweeter i have the crossover design + i know the guy that was on the design team at kef in the 1970s
I've just signed up for a new account - I'm looking for some help. Can I convert KEF 104's to 104ab's by replacing the crossover? From the threads it looks like they have the same drivers....

David
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Old 20th November 2008, 12:15 AM   #9
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Default Re: Re: kef 104

Quote:
Originally posted by bdgdpc
Can I convert KEF 104's to 104ab's by replacing the crossover?
Yes. I'd build one from scratch with better parts. The box could use some work too.

dave
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Old 20th November 2008, 03:00 PM   #10
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Default Re: Re: Re: kef 104

Quote:
Originally posted by planet10


Yes. I'd build one from scratch with better parts. The box could use some work too.

dave

Thanks. I'm sure I saw a circuit diagram somewhere....

David
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