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Old 21st July 2012, 03:57 PM   #121
MiiB is offline MiiB  Denmark
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This is a very internesting subject...But I'am afraid there's no magic formula.. I have found that bigger is not by all means better. Long time ago i had some special caps made, I have for my loudspeaker had a 200 uF copper plated aluminium/polypropylene T-line cap manufactured (terminals at the center of the winding). these were and are the best i have ever heard for my speakers. Now for fun I asked if they could do something similar for an elco for a Power amp, so I had some rather big ones made 27mF also with the terminals in the middle of the winding. (idea was to reduce inductance by the shorter current and charge distances. All's well apart from the fact that thy are beat in all musical terms by 6.8mF Rubycons.
Nico... I do believe in the distributed capacitance to avoid rail from becoming uneven for each of the output devices..And I have this currently playing of a SSA variation that I did with Sonya.

Still have to get the understanding of the size thing... I do believe size matters
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Old 21st July 2012, 04:09 PM   #122
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Hope everybody appreciated the specs of this cap

Quote:
Originally Posted by OnAudio View Post
There are very interesting caps now available
Click the image to open in full size.

B41456B8109M EPCOS Inc | 495-4224-ND | DigiKey
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Old 21st July 2012, 04:10 PM   #123
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Quote:
Originally Posted by AKSA View Post
Tom,

My real concern is the level of the charge pulse coming off the rectifier to charge the filter cap.

Go too high, and this current is huge, impacting the earth return currents from the speaker voice coil.

With around 10mF, I have noted that a BYV32E UFSR rectifier is needed; a BYC28E with surge rating around 70A will blow from time to time.

There comes a point where large filter caps need large rectification and drive large charge currents, which seem to have deleterious effect on sound quality. I see similar compromises here to say, the cam timing on an IC engine. It is vexing indeed......

I have built 75W amps with just 2000uF of filter capacitance. Bass and impression of speed has been exceptional. I have even used just 1000uF with little perceived loss of quality or noise performance. Make the caps 4,700uF and again, there is little perceived improvement in sound quality. Make it 10,000uF and rectifiers begin to break, at least the 35nS rectifiers I like to use. And the perception of speed seems somehow to slow.

These are all subjective observations, and as such are raised because they are interesting, but the explanation does not seem clear to me.

Cheers,

Hugh
Hi Hugh,

Would you say that my methodology provides consistent guaranteed results and satisfaction
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Old 21st July 2012, 04:16 PM   #124
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I've never found it necessary to use High Speed rectifiers. Standard 50A bridges sound just as good to me.

A good amplifier design will have a good PSRR so you are only really striving for a low impedance supply. This is being borne out by those that have got away with relatively low reservior cap values.

Also one 10000uF cap can be VERY different to another. You CAN buy cheapie 10000uF caps but you can also buy VERY expensive ones.

As I said earlier. A bank of reasonable quality low ESR caps will probably be the best of all worlds. If you buy one of the cheapuie E-Bay capacitor boards that take multiples of smaller caps you can play away and listen to the results without having to sell the wife.

Here is one example http://www.ebay.co.uk/itm/6-10000uF-...item4aa48f1d55

There are many boards in many different configurations.

Last edited by KatieandDad; 21st July 2012 at 04:30 PM.
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Old 21st July 2012, 04:43 PM   #125
MiiB is offline MiiB  Denmark
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ohh....there much more to that with the caps and the rails than ripple...bear in mind that the rails are effectively modulated with the music signal, so by default and by current paths the supply capacitors are directly in the signal path.
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Old 21st July 2012, 04:57 PM   #126
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Quote:
Originally Posted by MiiB View Post
ohh....there much more to that with the caps and the rails than ripple...bear in mind that the rails are effectively modulated with the music signal, so by default and by current paths the supply capacitors are directly in the signal path.
My point from the outset, mains related ripple is one issue that manifests itself as hum, signal related ripple masks low intensity detail without knowing it. It does not show up measuring the amplifier output or using FFT, it is only detectable by ear if you know what a good amp sounds like.

This afternoon I fooled with two extremes, 80 000uF per rail capacitors versus a single 4700 uF per rail. Now here is were I get shot down. Bass is better with the big caps but on the other hand the small cap allows me to hear so much more music.

Do not for a moment think I am now converted, this is fooling around for a few hours using my normal listening amp. It was easy to swap between the caps as wires are bolt on.

All my caps are from Krummer in Germany (I don't think anyone has heard of these)

Katie&Dad here is a low budget cap.
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Old 21st July 2012, 05:01 PM   #127
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Hugh are you sure that it is subjective? Everything we hear, feel see or smell is not subjective. There is nothing nice about smelling a fart.

The power supply may just be the reason why different amps sound different and it may be less subjective or not subjective at all. That is what I would like to establish here, is there an optimal value, and if there is it should be definable and calculable, there can be no black magic, this is science like any other science.
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Last edited by Nico Ras; 21st July 2012 at 05:27 PM.
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Old 21st July 2012, 05:16 PM   #128
MiiB is offline MiiB  Denmark
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this was exactly the same outcome i had wit my test of 4x27mF vs a single 6.8mF cap...The smaller cap was by far more musically right.. In separated therms the bigger cap boasted more edges in the base..but not more coherence. Could be that we need some kind of singularity in the signal path...could be that Hugh's separation is the way to go.. like in one BIG bank followed by a smaller RC cell close to the output, this way the musics modulation could be handled by one cap/bank...Or the two different modulations can be handled by separate capacitor banks.

Last edited by MiiB; 21st July 2012 at 05:34 PM.
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Old 21st July 2012, 05:31 PM   #129
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Quote:
Originally Posted by AKSA View Post
Tom,

I have built 75W amps with just 2000uF of filter capacitance. Bass and impression of speed has been exceptional. I have even used just 1000uF with little perceived loss of quality or noise performance. Make the caps 4,700uF and again, there is little perceived improvement in sound quality. Make it 10,000uF and rectifiers begin to break, at least the 35nS rectifiers I like to use. And the perception of speed seems somehow to slow.

These are all subjective observations, and as such are raised because they are interesting, but the explanation does not seem clear to me.

Cheers,

Hugh
Quote:
Originally Posted by Nico Ras View Post
This afternoon I fooled with two extremes, 80 000uF per rail capacitors versus a single 4700 uF per rail. Now here is were I get shot down. Bass is better with the big caps but on the other hand the small cap allows me to hear so much more music.

Do not for a moment think I am now converted, this is fooling around for a few hours using my normal listening amp. It was easy to swap between the caps as wires are bolt on.
Quote:
Originally Posted by MiiB View Post
this was exactly the same outcome i had wit my test of 4x27mF vs a single 6.8mF cap...The smaller cap was by far more musically right.. In separated therms the bigger cap boasted more edges in the base..but not more coherence.

I did try to publish an article on this 6 years ago, but it was not approved, guess the time is now
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Old 21st July 2012, 05:38 PM   #130
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Quote:
Originally Posted by OnAudio View Post
I did try to publish an article on this 6 years ago, but it was not approved, guess the time is now
Why not Harrison it takes persistence to establish a radical idea.
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