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Multi-Way Conventional loudspeakers with crossovers

KEF R900 crossover upgrade
KEF R900 crossover upgrade
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Old 28th October 2019, 02:57 PM   #1
douede is offline douede
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Default KEF R900 crossover upgrade

Hi folks ,

I would like improve the sound of the my KEF R900 speakers by upgrading its crossover parts, and am thus looking for suggestions, advices, feed-back...


You will find attached my pictures of its crossover (world premiere !).

Thanks a lot .

Douede
Attached Images
File Type: jpg _KEF R900_Filtre_Schema.jpg (47.1 KB, 243 views)
File Type: jpg KEF R900_Filtre HF_0b.jpg (49.0 KB, 242 views)
File Type: jpg KEF R900_Filtre LF_0c.jpg (35.5 KB, 245 views)
File Type: jpg KEF R900_measure.jpg (35.0 KB, 243 views)

Last edited by douede; 28th October 2019 at 09:02 PM.
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Old 28th October 2019, 03:16 PM   #2
Zvu is offline Zvu  Serbia
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Only thing that would bring some improvement in their crossover would be upgrade of 3mH coil in woofer section. You should upgrade to air-coil but try to keep Rdc the same - it is somewhat highish.

Bypass those elcos with some small foil caps and that would be it. Everything other than complete redesign would be a waste of time and money.
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Last edited by Zvu; 28th October 2019 at 03:19 PM.
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Old 28th October 2019, 03:53 PM   #3
douede is offline douede
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Zvu, thanks for your answer.
So you think no (safe) improvement by upgrading caps (and resistors) in serie with HF adn MF ?.
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Old 28th October 2019, 09:04 PM   #4
Zuhl is offline Zuhl  England
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These are fine speakers and upgrading the caps would be well worthwhile.

The difference between electrolitics and even modest caps will be noticeable. Something like Ansar Supersound caps would work nicely. You'd need to replace the boards, as they won't be big enough for these caps. The only real issue you face is the size of some of the caps. It may well prove too expensive (and space eating) to replace them with non electrolitics - a bypass cap may be your only option.

The inductors can be replaced with air cored, especially the tweeter ones. The others will be ok as long as you don't push the speakers too hard.

Resistors can be left as is - upgrades are expensive and offer minimal improvements.
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Old 28th October 2019, 09:20 PM   #5
douede is offline douede
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Zuhl, thanks for your answer.


I am not affraid having to move parts, solder them directly to each other, put them on another board, even put the boards out of the speaker enclosure.
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Old 28th October 2019, 09:25 PM   #6
Zvu is offline Zvu  Serbia
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I see now that there is elco series to midrange. Upgrade at that place to foil cap would also be ok. But again, i wouldn't go wild with Mundorfs or Duelunds. Kef dual concentrics are great drivers but with their factory crossovers are firmly positioned in a certain class of sound. Changes in sound throwing high price xover components at it, while maybe evident, aren't that large to make it worth the hassle.

And don't expect to hear large differences if you change elcos on woofer crossover to foil caps. Both elcos (170uF and 280uF) are used in such a manner that it will not make significant difference but will cost a small fortune.
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Last edited by Zvu; 28th October 2019 at 09:30 PM.
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Old 28th October 2019, 11:26 PM   #7
chris661 is offline chris661  United Kingdom
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What Zvu said.

Throwing higher-price components around doesn't mean the sound will get any better.


What is it about the speakers that's lacking at the moment?

Chris
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Old 29th October 2019, 12:32 AM   #8
Galu is offline Galu  Scotland
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OK, I will play devil's advocate.

I would trust KEF to have got the crossover right at this price point.

My advice would be to sit back and enjoy the music.

If you really feel the urge to tinker, then consider going down the diy speaker route.
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Old 29th October 2019, 12:32 AM   #9
douede is offline douede
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Quote:
Originally Posted by chris661 View Post
.../...
What is it about the speakers that's lacking at the moment?
Chris


How i would like to improve the sound ? :
- General: More transparency and breathing (less enclosed/dark).

- HF: Less plastic, but still without becoming harsh (rich HF music).

- MF: More open/fluid, but still without becoming messy (rich MF music)
- LF: More "savage", quick, slam, vibrant... (less round/slow/heavy, "british"...).
To sum up, more transparent and neutral sound, but still never becoming harsh (when playing pop/rock music), which is one of the R900's sound characteristic.
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Old 29th October 2019, 01:17 AM   #10
cotdt is offline cotdt  United States
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I upgraded the capacitors in my Kef LS50 and it made a difference, even though the capacitors were all already film capacitors. Applying digital EQ for a flat response made an even bigger difference (as expected).

Here in the R900, the response is already pretty flat, but the electrolytic capacitors and low-grade film capacitors need to go. The inductors look to be good quality already, so I would leave them alone.
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