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Multi-Way Conventional loudspeakers with crossovers

KEF LS50 - crossover?
KEF LS50 - crossover?
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Old 6th July 2018, 04:20 PM   #11
simon dart is offline simon dart  United Kingdom
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Steve,

The KEF drivers in the LS50 are 4 ohm. Definitely! Also although the drivers are coincident in X and Y, they aren't quite in Z. I measured them. The tweeter is connected in reverse polarity.
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Old 6th July 2018, 10:26 PM   #12
ernperkins is offline ernperkins  United States
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Wondering what your measured Z-axis value turned out to be.
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Old 7th July 2018, 03:38 AM   #13
system7 is offline system7  United Kingdom
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I said I wasn't too sure about polarity. We don't know what KEF are doing here. My feeling is time alignment is not too big an issue with a 5" bass anyway. Can only be a couple of centimeters out even with a regular tweeter on a baffle.

It could be a BW3 alignment on the filter, which is very KEF, and that works in either polarity.

But 4 ohms is a game changer. I hadn't researched that. But usual stuff on the circuits to adjust, smaller coils and resistors, bigger capacitors. In fact, 1mH series and 10uF shunt (maybe with a bit of resistance like 2.2R added in series with the capacitor) on the bass might then do, with 3.3uF and 0.33mH and an attenuator on the (8 ohm?) tweeter.

Acoustic centre is usually the middle of the voicecoils, so you can work Z out for the Coaxial. But it's tiny relative to 3kHz wavelength of 10cms. The good news is that 5" bass is an easy speaker. So I'd get on with it.
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Old 7th July 2018, 07:18 AM   #14
Soldy is offline Soldy  Germany
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Quote:
Originally Posted by simon dart View Post
Steve,

The KEF drivers in the LS50 are 4 ohm. Definitely! Also although the drivers are coincident in X and Y, they aren't quite in Z. I measured them. The tweeter is connected in reverse polarity.
You don't happen to have a picture of the crossover where the part specifications can be seen?
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Old 9th July 2018, 05:39 AM   #15
Soldy is offline Soldy  Germany
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Is that a no, or didn't you see my post?
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Old 10th July 2018, 03:31 PM   #16
simon dart is offline simon dart  United Kingdom
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@Soldy, I don't know the full schematic, even if I did I'd be reluctant to share KEF's intellectual property in public. These speakers are still in production. You can't see the capacitor values as they are wrapped in some sort of damping goo in any case.

@ernperkins, I measured the drivers just out of curiosity some time ago when I first got the speakers, they are very well behaved, but I didn't record the measurements. Sorry!
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Last edited by simon dart; 10th July 2018 at 03:43 PM.
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Old 11th July 2018, 07:34 PM   #17
Soldy is offline Soldy  Germany
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I din't expect you to share in public, a PM would have been fine


But since you don't have it, it doesn't matter.
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Old 15th July 2018, 09:06 AM   #18
Soldy is offline Soldy  Germany
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No one who can help?
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Old 17th July 2018, 05:52 AM   #19
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No one?
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Old 21st July 2018, 07:45 AM   #20
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