KEF 105.1 HELP NEEDED.. - diyAudio
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Old 19th April 2015, 10:29 PM   #1
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Join Date: Apr 2015
Default KEF 105.1 HELP NEEDED..

Hi there guys and gals.. I am new to the site and i am really hoping someone could help me? I just bought a beautiful pair of kef 105.1 speakers yesterday for a really good price but the reason why they were cheap is because the midrange speakers in each speaker were not working.. Now i tested the midrange drivers and they work good if not hooked up the the cross over but i cannot get any sound when i hook up the cross over.. All fuses are good ect! ect! i am not sure where or hope to check to see if there is something blown in the cross over?? i checked all solder joints and wiring ect!! i would like to have them rebuilt and i was wondering if anyone could help me with what i need and what caps i sould get? I do not want to spend alot of money but want some decent caps.. any help would be great.. Or if there is a place that sells the complete recapp kit? many thanks...
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Old 19th April 2015, 11:47 PM   #2
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Location: Queensland Australia
It does sound like a capacitor. Now one cheap way of finding out the source of the problem is to buy two cheap bi-polar electrolytic say 30uF to 50uF and (35 working voltage) the values don't matter at this stage. The 105 had a 4th order cross over so there should be two cap in series with each mid range driver. Remove them and replace them with your new caps.
See if that works. Mind you it is an odd problem, btw did that model have a "whoop doo"
protection circuit? If so that might be an issue.
If you want all the KEF gurus clustering around and helping then there is a site dedicated to KEFs simply called "hifiloudspeakers". Fiddling with older Kefs is all they do.......mountain of info'
They are a kindly bunch and will prove v helpful.
Good luck, Jonathan
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Old 19th April 2015, 11:58 PM   #3
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Thank you very much I am kinda new to all this I hope that will fix the problem I will try it tomorrow. Should I recap the whole cross over and could you recommend any caps I should try? Thank you
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Old 20th April 2015, 05:15 AM   #4
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I am not a KEF "guru" so I am not jumping in with free advice that may not be correct. Change the dodgy ones first and see if that cures the problem. Those speakers are around 40 yrs old so the electrolytics will tend to dry out. These days better quality plastic units re much more freely available and these should work well to replace the smaller values in the mid to tweeter cross over. These are often less than 10uF. The lower frequency ones will be larger values and a lot more expensive in plastic.
I do suggest you get on the "hifiloudspeaker" site. There is a lot of expertise there.
I think there is a diagram of your 105 cross-over in the technical section. Membership is free.
BTW if you work at this yourself and learn a bit about your unit and the caps you will save a LOT of money. There are people who will rebuild it commercially and charge the proverbial arm and leg. They are waiting for Baby Boomers like myself to spend our superannuation on fulfilling the dreams we put on hold 40 years ago when the kids education took priority over KEF 105's.............
So take your time and it will be a very satisfying and fairly cheap journey.
And other people will probably get on board this thread as the earth moves and new time zones kick in.
Your problem may have been experienced by others.
Just try and find the initial problem and see how things go after that.
Cheers, Jonathan
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Last edited by Jonathan Bright; 20th April 2015 at 05:18 AM.
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Old 20th April 2015, 10:42 AM   #5
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Thank-you for the info...
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Old 20th April 2015, 06:16 PM   #6
SaSi is offline SaSi  Greece
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hifiloudspeakers member chiming in...

I am attaching the x-over schematics for MkI and MKII (just in case). Assuming your xovers are MkI, if a capacitor is blown causing the midrange to mute, it's either C5 or C7 (30uF or 100uF).

You can try another non polar capacitor in place of these two suspect ones. I would be even adventurous to bypass them with a wire to see if these two are the cause of the problem - just don't raise the volume too much because the bypass would both eliminate any low pass in the xover and also unbalance the load to the amplifier just a bit.

Falcon acoustics in the UK (https://www.falconacoustics.co.uk/) specialize in spares and recap kits for KEF units and they have a reasonably price kit for the 105. I would (and should as I have an R105 awaiting recap) get a kit from them.
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File Type: jpg R105-1.jpg (69.3 KB, 31 views)
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Old 20th April 2015, 06:37 PM   #7
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Thank-you so much.. I love Kef speakers i own a pair of Tangent that have the Kef b200 and t27 tweeter they are like the rogers LS/35A speakers they have incredible sound for there size.. I want to thank everyone here for there help.. I am keeping an eye out for more vintage Kef speakers.. I just love them...
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Old 20th April 2015, 07:05 PM   #8
sreten is offline sreten  United Kingdom
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Location: Brighton UK
Hi,

Recap the whole lot with modern equivalents from falcon acoustics.

rgds, sreten.
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Old 20th April 2015, 07:09 PM   #9
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ok thanks i will order a set tomorrow.. thanks for all your help... everyone..
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