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Calinda Crossovers RE-CAP sp1055

 
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grayyyt
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Joined: 17 Jul 2010
Posts: 8

PostPosted: Sun Aug 08, 2010 10:18 pm    Post subject: Calinda Crossovers RE-CAP sp1055 Reply with quote

Confused Hello Again, Working on re-capping my Calinda crossovers, I'm having difficulty finding polystyrene capacitors. I have found Electrolytic caps. How well will they work? I cannot find a 7uf cap to save my life. But, I found a 2.2 & a 4.7 Electrolytic =6.9uf close enough????? Any & All help is Needed & appreciated Thanks Again, Keith
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audiolabtower
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Joined: 06 Jan 2009
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PostPosted: Mon Aug 09, 2010 12:03 am    Post subject: Reply with quote

polystyrene is only used in very small value caps. Kef used reversible electrolytic caps which are not the same as normal electrolytics (they are effectively twice the value back to back to accept a/c voltages).

Most recapping is done with polyester or polypropylene caps for relative expense reasons. These have significantly less loss factor than reversible electrolytics, so you may need a low value 5 or 10 Watt resistor of 1/2 ohm or thereabouts in series with the tweeter, otherwise the result might be brighter than original design.

Parallel caps to reach a specific value is a good way to do it. Some use a next value down reversible electrolytic and pad it up to value with a small polypropylenes to get the implied better high frequency performance of the solid core cap.

Unfortunately Kef measured the rev elec caps and put them in tolerance bands to suit the inductors and drive units they were matched with. Thus the printed value may only be a guide and the actual value when new could be some way from printed, either higher or lower depending on the other matched components. The only way to know for certain was to measure the original caps on a bridge when they were relatively new. Now they could have drifted.

However there is no reason you cannot try and end up with a sound that is acceptable for you with a little experimentation.
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proffski
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Joined: 22 Aug 2003
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Location: Tewkesbury UK

PostPosted: Wed Aug 11, 2010 12:03 pm    Post subject: Reply with quote

audiolabtower wrote:

However there is no reason you cannot try and end up with a sound that is acceptable for you with a little experimentation.


Been my motto for a while, "The sound could end up being different" but as long as it does not offend...
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