replacement caps for 107 crossover

dayking79 · 15th May 2009, 04:48 PM

Hi,

while i am still waiting for my Kef 107 drive units to be rebuilt i was thinking of replacing the caps in the crossovers. There are 2 crossovers per speaker.
Below are the original caps, values and overall quantity (all have tolarance of 10%)
ALCAP 4.2uf 50 x 6
" 20uf 100v x2
" 40uf 100v x2
" 25uf 100v x2
" 300uf 25v x2
" 240uf 25v x6
" 50uf 100v x2
BENNIC BI-POLAR 10uf 100v x4
"100uf 50v x10
I suppose my first question is, do you think it is worth replacing all of them?
And what with?
Any help would be most appreciated. Thank you.

mjf · 15th May 2009, 07:13 PM

hello.
do you know how old are these caps?
greetings.........

dayking79 · 16th May 2009, 08:06 AM

Hi,
well the speakers are around 25 years old and i think they are the original caps.

mjf · 16th May 2009, 09:04 AM

they are really old........and perhaps a little bit dried out ( i presume these all are electrolytic caps; you must not change film/foil caps).
if you swap to new parts the sound will change a bit........perhaps you will listen first with the old caps .......... and change them part by part to the new ones...............
there are many elco's with high values.do you have a schematic or so?
nowadays elcos have a liittle bit different values,e.g. 22uf for 20uf,47uf for 50,........and so on.perhaps you will parallel some elcos to get these numbers.
greetings............

Geoff H · 16th May 2009, 03:06 PM

That's the real question; "with what" Those speakers were built in an era when quality was available. Your caps may well be quite usable. I would invest in a multimeter with a capacitance range and measure or perform a frequency sweep over the crossover frequencies first.

I've been looking for caps for a new amp. What I've found so far has a life expectancy of 2000 hours. But that keeps me employed

They also have a 20% tolerance.

Regards

dayking79 · 18th May 2009, 12:22 PM

Hi and thanks for the replies.

Yes, i think i may well test the caps porperly first as i wouldn't want to replace them if i can't get exact value replacements.

Will let you know what i find. Thank you.

15th May 2009, 04:48 PM	#1
dayking79 diyAudio Member Join Date: Aug 2008	replacement caps for 107 crossover Hi, while i am still waiting for my Kef 107 drive units to be rebuilt i was thinking of replacing the caps in the crossovers. There are 2 crossovers per speaker. Below are the original caps, values and overall quantity (all have tolarance of 10%) ALCAP 4.2uf 50 x 6 " 20uf 100v x2 " 40uf 100v x2 " 25uf 100v x2 " 300uf 25v x2 " 240uf 25v x6 " 50uf 100v x2 BENNIC BI-POLAR 10uf 100v x4 "100uf 50v x10 I suppose my first question is, do you think it is worth replacing all of them? And what with? Any help would be most appreciated. Thank you.

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15th May 2009, 07:13 PM	#2
mjf diyAudio Member Join Date: Jan 2009 Location: upper austria/near linz	hello. do you know how old are these caps? greetings.........

16th May 2009, 08:06 AM	#3
dayking79 diyAudio Member Join Date: Aug 2008	Hi, well the speakers are around 25 years old and i think they are the original caps.

16th May 2009, 09:04 AM	#4
mjf diyAudio Member Join Date: Jan 2009 Location: upper austria/near linz	they are really old........and perhaps a little bit dried out ( i presume these all are electrolytic caps; you must not change film/foil caps). if you swap to new parts the sound will change a bit........perhaps you will listen first with the old caps .......... and change them part by part to the new ones............... there are many elco's with high values.do you have a schematic or so? nowadays elcos have a liittle bit different values,e.g. 22uf for 20uf,47uf for 50,........and so on.perhaps you will parallel some elcos to get these numbers. greetings............

16th May 2009, 03:06 PM	#5
Geoff H diyAudio Member Join Date: Oct 2006	That's the real question; "with what" Those speakers were built in an era when quality was available. Your caps may well be quite usable. I would invest in a multimeter with a capacitance range and measure or perform a frequency sweep over the crossover frequencies first. I've been looking for caps for a new amp. What I've found so far has a life expectancy of 2000 hours. But that keeps me employed They also have a 20% tolerance. Regards

18th May 2009, 12:22 PM	#6
dayking79 diyAudio Member Join Date: Aug 2008	Hi and thanks for the replies. Yes, i think i may well test the caps porperly first as i wouldn't want to replace them if i can't get exact value replacements. Will let you know what i find. Thank you.

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