KEF Reference 101 Loudspeakers. Crossover update - diyAudio
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Old 27th January 2010, 06:14 PM   #1
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Default KEF Reference 101 Loudspeakers. Crossover update

for anyone interested I'm going to describe my renewal of the crossovers of these classic speakers which I've had from new.

First, after I removed the 'woofer' to get access to the crossover inside, there is a screw underneath on the outside once remover the crossover was still well attached and I had to lever it off, which was awkward inside the cabinet!, there was four sticky pads holding it there.

The first things I noticed were that the 15R 6W vitreous enamel resistor looked soiled with corrosion(?), a white powdery coating. and two 10v (only!?) caps on the protection circuit had corroded PCB tracks underneath. This was on BOTH crossovers!

I enclose a picture of one of the crossovers
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File Type: jpg KEF 101 Crossover.jpg (231.0 KB, 611 views)
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Old 27th January 2010, 09:48 PM   #2
gfiandy is offline gfiandy  United Kingdom
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Hi,

I recently measured the components in a lesser KEF the CODA III however it appears to use the same make of capacitors ALCAP. If yours are anything like mine expect them to be well under value by now.

EG.

marked measured
3.3---------3.1
5-----------4.7
6.6---------5.9

Regards,
Andrew

Last edited by gfiandy; 27th January 2010 at 09:49 PM. Reason: added dashes as spaces removed by system
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Old 27th January 2010, 10:48 PM   #3
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Quote:
Originally Posted by gfiandy View Post
I recently measured the components in a lesser KEF the CODA III however it appears to use the same make of capacitors ALCAP. If yours are anything like mine expect them to be well under value by now.
Again for others that's not all, better than, or to make it proper, a matched (caps) pair should give better and more important results. So measured both before install, or the buy 3/4 units mount or use 2 idea must work better also in some cases (when they are not expensive or when you have many).
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Old 22nd March 2010, 07:40 PM   #4
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I got this crossover diagram off the internet.... somewhere Some components might be changed in later models?
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Old 23rd March 2010, 04:38 AM   #5
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The very ordinary components in such a quality speaker is quite surprising.
I would replace EVERY component on that board with decent quality modern equivalents.
Ditch the relay too.
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Old 23rd March 2010, 05:36 AM   #6
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Quote:
Originally Posted by David Gatti View Post
The very ordinary components in such a quality speaker is quite surprising.
I would replace EVERY component on that board with decent quality modern equivalents.
Ditch the relay too.
I would second that.

dave
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Old 23rd March 2010, 06:17 AM   #7
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I really doubt changing components will make any difference. It's actually good to know reputable company like KEF uses ordinary components even on their Reference line. They must be good enough.
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Old 23rd March 2010, 06:53 AM   #8
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I really doubt changing components will make any difference.
ha, ha, ha... elcos alone will have passed their use by date...

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Old 23rd March 2010, 09:32 AM   #9
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This board looks like a horror movie to me. If the attached circuit diagram is indeed correct and there is 4 x 100uF in series with the crossover i would start by shorting those out. Either get really good electrolytics or try to squeeze in films for the rest.
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Old 23rd March 2010, 09:36 AM   #10
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I'd agree that the electolytics will be passed their use by dates and recommend replacing them with polyprop's. But, you might find the trebble becomes subjectively a little louder and you might choose to replace the 2R2 padding resistor with a 2R7 resistor.

I recall really enjoying listening to the kef 101 about 15 years ago (in my mis spent youth) so I think you will enjoy upgrading these speakers.

The 4 parallel 100uF caps shown at the input of the crossover are interesting but, assuming this schematic is correct you could probably wire the tweeter network to the positive terminal, rather than the other side of these caps - that might also improve the quality of the trebble.

Nick
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