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Do electrolytics values stay constant ?
Do electrolytics values stay constant ?
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Old 20th September 2019, 10:22 AM   #1
lolilol1975 is offline lolilol1975
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Default Do electrolytics values stay constant ?

Hello,

I want to recap a pair of 25 year old KEF 105/3 with new electrolytic caps (the high values and little space on the board leave me little choice). However, I've read that for these speakers, KEF used to select cap values specific to each driver, with a tolerance of 1%.

So ideally, I should measure the original caps and try to match them as closely as possible. Hence this question: do electrolytics capacitance drift when they age, making this measurement moot, or do their values stay constant, and only the ESR increases ?
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Old 20th September 2019, 10:50 AM   #2
analog_sa is offline analog_sa  Europe
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Do electrolytics values stay constant ?
They most certainly drift.
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Old 20th September 2019, 10:59 AM   #3
lolilol1975 is offline lolilol1975
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OK, so I guess I should just get the values of the schematics.
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Old 20th September 2019, 11:01 AM   #4
alayn91 is offline alayn91  France
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Hello,
"do electrolytics capacitance drift"
Yes, they drift. This is called aging.
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Old 20th September 2019, 11:30 AM   #5
davidsrsb is offline davidsrsb  Malaysia
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Not just age, the value will change with temperature and also on recent usage due to reforming by the music signal
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Old 20th September 2019, 12:35 PM   #6
Galu is offline Galu  Scotland
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This diyAudio thread may be of interest to you in regard to the potential re-capping of the KEF 105/3. Kef 105/3 crossover
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Old 20th September 2019, 12:47 PM   #7
Galu is offline Galu  Scotland
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I don't know your location, but Falcon Acoustics can supply a replacement capacitor set for the KEF 105/3.

KEF 105.3 REPLACEMENT CAPACITOR SET
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Old 20th September 2019, 01:02 PM   #8
lolilol1975 is offline lolilol1975
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Quote:
Originally Posted by Galu View Post
I don't know your location, but Falcon Acoustics can supply a replacement capacitor set for the KEF 105/3.

KEF 105.3 REPLACEMENT CAPACITOR SET
Yes, thank you, I've ordered the set. The guy at Falcon acoustics told me that the caps are following the values in the schematics because there is no way to know the exact values for my pair (KEF supposedly has them but they won't bother answering such a request, quite honestly disappointed with this company). Also, because the drivers have aged, it doesn't matter anyway, according to him.

Nevertheless, I don't like that the crossover has so many caps and that the board is so small (a 19 cm square) that nothing else than small electrolytics will fit. Right now I am not listening to music, I'm listening to electrolytics.
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Old 20th September 2019, 01:24 PM   #9
analog_sa is offline analog_sa  Europe
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Do electrolytics values stay constant ?
One option is to build external crossovers in case you like the speakers enough. It is very easy to get carried away though
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Old 20th September 2019, 01:48 PM   #10
Galu is offline Galu  Scotland
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Quote:
Originally Posted by lolilol1975 View Post
Right now I am not listening to music, I'm listening to electrolytics.
In my opinion, there's nothing wrong with the 'sound' of properly chosen electrolytics.

In fact, replacing electrolytic capacitors with film capacitors can upset the sound balance of vintage speakers because of changes in equivalent series resistance (ESR).
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