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Old 25th April 2009, 03:22 PM   #1
UV101 is offline UV101  England
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Default X-Over capacitor upgrade

Hi Guys,

I have recently tried replacing the capacitors in my x-overs.

The speakers are Focal 716v. The xovers have a 6.8uF electrolytic on the low pass filter which I have replaced with a mundorf supreme of the same value with excellent results.

The high pass for the tweeter seems a little more complicated than I 1st thought!

The cap (which looks like an mkp) is 3.9j which i took to be 3uF. I replaced with Mundorf Supreme 2.7uF which I expected to slightly tame the brightness of the speakers.

The result is that I've killed the high treble! Upon re checking, the value 3.9j should be 3mF and not 3uF? (3.6j= 3uF 5%)

1st, can someone agree or disagree with the above please!!??

2nd If it is indeed 3mF what could I use to upgrade the std items!


Thanks in advance for you comments

Ian
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When Bitstream came out, I thought, “my God, what are we going to do...?” Ken Ishiwata http://www.hifisounds.co.uk
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Old 25th April 2009, 05:22 PM   #2
mjf is offline mjf  Austria
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hello.
this cap should be 3,9uf.............this value is available, e.g. the foto shows a mkt..............
suggestion: you can add a 1uf to your 2,7uf (paralelling caps) so you get 3,7uf..........
greetings...............
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Old 25th April 2009, 05:33 PM   #3
AndrewT is offline AndrewT  Scotland
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Hi,
swapping electrolytic to plastic film will alter the sound that the designer built into the crossover.

You will have to change the values and resistances of most of the components to get the sound balanced again. It may never sound as good as the original.
If you are very lucky and after a lot of swapping it might equal the original. The chances of you bettering the original are almost nil.

3.9 = 3u9F
j = 5% tolerance.
MKP = metallised polypropylene.
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Old 26th April 2009, 10:20 AM   #4
UV101 is offline UV101  England
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Thanks guys, I don't know why I didn't think the same! I just saw the numbers with no units and went straight to an online calculator!

Quote:
Originally posted by AndrewT

You will have to change the values and resistances of most of the components to get the sound balanced again. It may never sound as good as the original.
If you are very lucky and after a lot of swapping it might equal the original. The chances of you bettering the original are almost nil.

Andrew, why would altering the quality of the components make the sound worse? I have used Mondorf supreme caps in my valve stage and for dc decoupling on the output of several CD Players I have modded. In my experience Replacing cheap elco's or MKP's in the audio path with this type of quality cap is one of the most effective mods I have made.

Replacing the 6.8uF eleco in the low pass filter with an identical value Mundorf supreme was a revelation. The sound is more open with far more energy than before. If there is a downside, I certainly can't hear one!

Ian
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When Bitstream came out, I thought, “my God, what are we going to do...?” Ken Ishiwata http://www.hifisounds.co.uk
JA-88D Class A, Audio Aero Capitole MKII, Focal and Kimber "Leave Nothing as Standard"
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Old 26th April 2009, 10:55 AM   #5
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Pick up a cheap LC/LCR meter.
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Old 1st May 2009, 09:57 AM   #6
UV101 is offline UV101  England
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Question Is upgrading xover caps really a bad thing?

Hi Guys,

After my school boy error, I've hooked up another 1uF across the new 2.7uF giving me a total of 3.7uF much closer to the original 3.9uF.

The speakers were a little bright previously and I expected to very slightly tame them with the .2uF difference.

The results - Absoulutely outstanding! Those Mundorf Caps are clearly worth their reputation. Bass is lower and tighter definately more accurate. The higher frequencies are sweeter, less hard and there is definately more detail present. A worthwhile upgrade for sure!!!

Andrew, I'm still interested in your theory that i'll never get these as good as the munfacturer did now I've messed about with the xovers? I have to be honest and say that in the sub £1000 speaker market, no components will be specially selected for their characteristics. This given, a straight forward mkp is used on the high pass filter and a pretty bog standard elco used for the low pass filter. Changeing these components to any audiophile capacitor suitable for xover networks surely has to be a good thing? I do understand that playing with the xover frequency may very well leave holes in the overall freq response of the speaker or even reinforce if you create additional overlap. I also appreciate that with my lowering of cap value (.02uF) i've raised the xover freq for the tweeter potentially creating a dip between the mid and the tweet. That aside, I'd still like to understand you comments. I've plenty of experience with Mundorf Supreme caps and I've yet to find an area where they make the overall sound worse.

Ian
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When Bitstream came out, I thought, “my God, what are we going to do...?” Ken Ishiwata http://www.hifisounds.co.uk
JA-88D Class A, Audio Aero Capitole MKII, Focal and Kimber "Leave Nothing as Standard"
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Old 1st May 2009, 10:53 AM   #7
AndrewT is offline AndrewT  Scotland
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it's not my theory.

I think it's more to do with the way manufacturers produce their product.

They assemble the best speaker they can for the money. They swap and adjust values/types of components to get the sound that will sell the highest quantity.

Changing one or two component types will completely alter the "balance" they have striven to achieve to make the sound "favourable".

Unless you are prepared to match their experience and the time and the resources they have available, I believe it will be no better than luck to match the performance that the manufacturer has achieved.
To better it without that investment is probably worse than luck.
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Old 1st May 2009, 01:43 PM   #8
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Ian, of course you have experience, if not you would not try that tweak, at least to make it sound better, and also check this. Let's say you have two MKP's one on the woofer and another on the tweeter circuit. I bet your system would get better if you would change your "low frequencies" MKP (downgrade) for an electrol cap and the one on the highs/tweeter (upgrade) with a better one, it all depends case by case.

Out of curiosity, I am very much interested in their xover, do you have the diagram (maybe also the reference for their speakers).

(Also) How would you compare them with the JBL's LS80, or how do you like them.
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