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Kef 304/ Concord IV

 
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Charles33
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Joined: 01 May 2014
Posts: 2
Location: Bordeaux- France

PostPosted: Fri May 02, 2014 7:17 pm    Post subject: Kef 304/ Concord IV Reply with quote

Good evening gentlemen,
I am Charles, a new comer from France and more precisely from Bordeaux, the place where they are supposed to produce some good wine.

Since recently, I own a pair of 304 (knowned also as Concord IV) in good and pleasant state. That is why I have requested to join your community. Though I have already some British speakers, the 304 are my first from Kef.
Full and detailed presentation can be seen here (sorry, it's a French forum from where I try to be an accurate moderator):
http://www.audiovintage.fr/leforum/viewtopic.php?f=20&t=42757

As can be seen in this presentation, photo "Kef 5.jpg" (from me) clearly points out that a 4uf capacitor has been added to a 4,2uf. I don't know if this addition was realised by the last owner or the guy before or even at the beginning. Having searched the crossover scheme of Condord IV, this doesn't fit from the original, though the added capacitor is an old black/red Elcap.
From your point of you, does this addition can be considered as an upgrade or should I sack the intruder ?

Anyway, these speakers sound pretty nice, smooth and gentle as many British speakers, though I still give my preference to Ditton 44 and Dalesford D major Embarassed (sorry for that).

Elcap capacitors are having a bad reputation of being bad when getting old (like me Evil or Very Mad ). They are still in the specs in capacity (more or less) but don't know about there ESR for not having the appropriate device.
Should a complete change of capacitors would improve ?
If so, do low loss Alcap are appropriated capacitors ?

I apologise for my poor English.

Charles33
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speakerguru
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Joined: 18 Nov 2005
Posts: 959
Location: Green Hut, Tovil

PostPosted: Sat May 03, 2014 10:08 am    Post subject: Reply with quote

As I've explained in a previous post:
"KEF used to buy in all the capacitors at +/-10% or sometimes +/-20%. Then they would measure them all in-house and sort them into 1% bins. If I remember correctly, any parallel combinations would always be sorted to end up with a less than than 0.5dB effect on the response (0.3dB Reference series). In other places the inductors would be wound to compensate. i.e if the capacitor was -6% the inductor would be wound +5% or whatever the calculation predicted would minimise the drift from nominal."
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Charles33
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Joined: 01 May 2014
Posts: 2
Location: Bordeaux- France

PostPosted: Sat May 03, 2014 8:10 pm    Post subject: Reply with quote

Apparently my English is so poor that the only answer is out of bounderies.
Sorry to have disturbed.
Bye
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audiolabtower
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Joined: 06 Jan 2009
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PostPosted: Sat May 03, 2014 11:01 pm    Post subject: Reply with quote

What guru is saying is that elcaps can and do drift after this many years but it would be difficult to guarantee that changing them with random 5% or 10% components would give the same response as when they left the factory since there was a selection process to the components to minimise drifts from centre by tolerances adding up in the wrong direction.

But if your caps have drifted by 30 or 50% (which is possible) then a set of new caps would be better, but you can't tell without measuring them.

Low loss elcaps might well have been used in Kef crossovers say d<0.04 @ 1 kHz for caps in tweeter and midrange sections.
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speakerguru
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Joined: 18 Nov 2005
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Location: Green Hut, Tovil

PostPosted: Sat May 03, 2014 11:24 pm    Post subject: Reply with quote

Charles33 wrote:
Apparently my English is so poor that the only answer is out of bounderies.
Sorry to have disturbed.
Bye


I don't understand what you mean by "out of bounderies" but by your response it would seem that my post may have caused offence. I cannot understand why and I can assure you that no offence was intended.

I merely meant that with the KEF process at that time you could not take the printed value on a capacitor to be anything other than a rough indication of a range of values.
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proffski
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Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Sun May 04, 2014 2:10 pm    Post subject: Reply with quote

Got me puzzled too, and English is my second language.
I thought that the question as well as the answer were perfectly comprehensible!
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