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Old 10th January 2003, 07:15 AM   #1
JDeV is offline JDeV  South Africa
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Default Purpose of Bypass caps

I asked these questions on another thread but did not get satsifactory answers, could somebody please explain?
Yes, I don't know much about electronics , yet.
Thanx for any answers and explanations.

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"Re: A new Aleph3 is born... "

quote:
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Originally posted by Smithers
......, 6x47000uF Caps bypased with Wima MKP10 1uF, Mcap Supreme (induciotnfree) 0.1uF and a 10nF .....
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Questions:

1. Does all this bypassing really help and what does it actually do ?
2. Why 3 differant values?
3. What type of caps works best for this purpose?
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Old 10th January 2003, 07:46 AM   #2
yeti is offline yeti  Germany
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Default Bypass

They use bypass capacitors because the electrolytics don't work too well with high frequencies.
That means the resistance of the electrolytics rises at higher frequencies.
So what they do is to bypass them with smaller caps of a better quality. Usually with polymer film types but you can use ceramic caps too.
They use different values because the smaller a cap is, the better it performs in the higher frequency range.
This way they combine high capacity with good high frequency performance.
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Old 10th January 2003, 07:53 AM   #3
Klaus is offline Klaus  Germany
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Default C Cascades

Even the best "elkos" are not really fast and capable to supress HF-distortions. I guess that is the reason why bypass caps do so much of positive audio effects.

The values and optimal kinds of Caps can just be found by listening test. I did it this way: first checked the basis of any cascade, an additional MKP (from Wima or simular good stuff). To big ones slowed down the music and made it "fat", I found just 1UF appropriate. Next step of the cascade: an extremely fast = inductance free Cap. The 0,1UF M-Cap Supreme from Mundorf is the best I know. More transparency, more details. But that is not all - extremely fast small KP Caps (like EMZ Serie B 33531, ERO KP 1830 etc.) really whipe away last dirt from the window we have to look through listening to the musik. Sorry for having mentioned just Europien product - but I have to buy here...

If I unconnect this cascade the sound really suffers a lot. The difference is that big that everybody here could immedeatly recognize without any double blind test ore other tests. I compared my Aleph 4 monos to other DIY Aleph 2 and original production Aleph 2. The cascaded Alephs really have blown away the others! Much mor definition, focus, transparency...

I think original products can just not afford this extra parts, their prices are quite high. For DIY no problem...

Test it and enjoy! But a warning: with not fitting bypass Caps the sound can be disturbed very easily - long listening tests are a must - and one step after the other. Become shure of what each cap is doing.

Of cause this cascades do the same in cross over loudspeaker networks.
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Old 10th January 2003, 08:03 AM   #4
JDeV is offline JDeV  South Africa
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Thanx for these answers, make sense to me now. I also read in other threads that bypass caps are connected across the bridge rectifiers, other diodes and other caps allover the circiuts. Is it for the same reasons? Will 1 do it in the same way?
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Old 10th January 2003, 08:59 AM   #5
Klaus is offline Klaus  Germany
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Default diode bypasses

Caps bypassed to rectifiers/diodes are used to smooth the cut off reverse current peak which causes HF distortions. They must be exactly fitting to be effective "cleaning".

Some times good soft recovery and ultra fast diodes sound better w/o any cap. Schottkys also. It can easily be checked in listening tests.
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Old 10th January 2003, 11:41 AM   #6
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When we design an amp we assume a "battery" as power source and we also assume that the voltage has low impedance at all frequencies (beyond the amp's upper limit). Why? Because amplifier theories assume low impedance power supply voltage. If we have too high imdedance we get unpredictable reasults, may colouring the sound.

Let me also point out that the method of bypassing can be a science alone. Linear had a document about that when they have measured a couple of circiuts.

http://www.linear.com/pub/document.h...pp&document=50

This application note describes the technical aspects, not the audiophilic, but it is very educational with lot's of pictures and practical circuits (this I like).

I couldn't find the document I was looking for. Linear had an another document where they had tested tantal, polyester, electrolytics etc. Anybody who knows what I'm talking about?
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Old 10th January 2003, 12:20 PM   #7
JDeV is offline JDeV  South Africa
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Thumbs up Real USEFUll stuff.

Quote:
Originally posted by peranders
Let me also point out that the method of bypassing can be a science alone. Linear had a document about that when they have measured a couple of circiuts.

http://www.linear.com/pub/document.h...pp&document=50

This application note describes the technical aspects, not the audiophilic, but it is very educational with lot's of pictures and practical circuits (this I like).

Now this is real good stuff, thanx alot. Everybody should check it out!!
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Old 18th February 2003, 07:50 PM   #8
wazzup is offline wazzup  Netherlands
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Can anyone tell me the difference between MKP and MKS caps, from WIMA? I want to order some for my DIY cd player, and see how it works out. I have zero experience in audiophile caps, well I know Black gates, and Jensen... But in the HF That just won`t cut it.

Tnx in advance
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Old 19th February 2003, 07:33 AM   #9
uli is offline uli  Austria
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Quote:
Originally posted by wazzup
Can anyone tell me the difference between MKP and MKS caps, from WIMA? I want to order some for my DIY cd player, and see how it works out. I have zero experience in audiophile caps, well I know Black gates, and Jensen... But in the HF That just won`t cut it.

Tnx in advance
MKP = Polypropylen film

MKS = Polyester film

Uli
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Old 19th February 2003, 08:19 AM   #10
Klaus is offline Klaus  Germany
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Quote:
Originally posted by wazzup
Can anyone tell me the difference between MKP and MKS caps, from WIMA? I want to order some for my DIY cd player, and see how it works out. I have zero experience in audiophile caps, well I know Black gates, and Jensen... But in the HF That just won`t cut it.

Tnx in advance

HI,

don´t ask me why - I mean a technical explanation. But IMHO MKP sound much better, MKS made at my tests all the time a "plastic-like sound". Maybe MKP behaves more neutral at current impulses.

Benchmark: most good Caps wourldwide use MKP (Audyn, Mundorf, Solen, ...) Hopefully they know, why.

Test both or buy MKP straight on.

regards

Klaus
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