"Audiophile capacitors in Power Supply - A real advantage or not?

[doggitz]

I am getting ready to build an external linear 19V power supply for an mini ITX music server. I will use appropriat e precautions for ripple, noise, rectifier snubbing, etc. I have been looking through the multitude of high end PSU's for ideas and note that most of them talk about using ELNA or some other audiophile grade electrolytics. I understand the passion (or should I say religion) for caps used in the signal path (e.g. as coupling caps especially in tube gear), but cannot understand how the use of "audiophile" electrolytics in the power supply to a computer could make any real difference. What am I missing ?

[Panelhead]

I am getting ready to build an external linear 19V power supply for an mini ITX music server. I will use appropriat e precautions for ripple, noise, rectifier snubbing, etc. I have been looking through the multitude of high end PSU's for ideas and note that most of them talk about using ELNA or some other audiophile grade electrolytics. I understand the passion (or should I say religion) for caps used in the signal path (e.g. as coupling caps especially in tube gear), but cannot understand how the use of "audiophile" electrolytics in the power supply to a computer could make any real difference. What am I missing ?

 

There are many good audiophile filter caps. Low impedance is just one of the benefits. Internal dampening. Bandwidth. Even ripple current capacity.

The use of switching power supplies has pushed manufactures to improve standard filter caps also. There are many lines of ultra low impedance caps from all major manufacturers.

My faves are Jensen 4 pole caps. These are different in having input and output terminals. Increases filtering by at least 20 dB. The distributed node LC filtering is very effective.

[sandyk]

I am getting ready to build an external linear 19V power supply for an mini ITX music server. I will use appropriat e precautions for ripple, noise, rectifier snubbing, etc. I have been looking through the multitude of high end PSU's for ideas and note that most of them talk about using ELNA or some other audiophile grade electrolytics. I understand the passion (or should I say religion) for caps used in the signal path (e.g. as coupling caps especially in tube gear), but cannot understand how the use of "audiophile" electrolytics in the power supply to a computer could make any real difference. What am I missing ?

 

Doggitz

 

If it is able to use TO220 style rectifiers, I would recommend devices such as the Cree C3D06060A–Silicon Carbide Schottky Diode series. The better electrolytic capacitors are also specified for Slew Rate, which governs the time they can respond to sudden power demands.

Some genuine Elna capacitors are available at reasonable prices on ebay. Panasonic also make good reliable electrolytic capacitors. e.g. the FC and FM series.

 

Alex

[Lauritsvd]

Hi.

I have a little question: How about placing some good capacitors localy, like at the samsung ssd for the os,

and at the PPA Va usb card ?

Maybe at or on the the MB too??

 

Think I have some Black Gates 100/100 laying around :-) from an old amp project:-)

[4est]

This pretty much sums it up. To the point, a power supply capacitor can have as much or more influence as a signal capacitor depending upon what and where it is used. If one looks at the graphs of a low ESR solid polymer cap vs a traditional aluminum electrolytic it starts to make sense. One ought to be careful just adding caps willy nilly too btw.

There are many good audiophile filter caps. Low impedance is just one of the benefits. Internal dampening. Bandwidth. Even ripple current capacity.

The use of switching power supplies has pushed manufactures to improve standard filter caps also. There are many lines of ultra low impedance caps from all major manufacturers.

My faves are Jensen 4 pole caps. These are different in having input and output terminals. Increases filtering by at least 20 dB. The distributed node LC filtering is very effective.

[JohnSwenson]

4est has nailed it. Particularly for computer use you need a supply that can respond to a VERY wide range transient loads, from single digit Hz. up to many MHz. Audiophile capacitors simply don't do this. There is NO single capacitor that does this, it doesn't exist. It takes multiple capacitors of different characteristics to do this well.

 

Unfortunately the common response to this is to parallel several different capacitors right at the output, this doesn't work either. The inductances of the different caps interact with each other causing high impedance at multiple frequencies.

 

So what do you do? I call it the hierarchy of charge. Put small very low inductance caps right at the load, those get fed by a regulator that has a solid polymer cap in the mid hundreds uF as its output cap (no more than that, anything bigger is too slow). That regulator is fed by some large traditional good quality electrolytics. For a normal type cap input filter you want a pre-regulator to deal with what comes out of this filter.

 

The two regulators provide isolation between different capacitor types, so that you can properly to the "very big slow caps, big medium speed caps, small very fast, and very small VERY fast caps".

 

The very fast cap at the end can respond VERY quickly to load transients, but it can't do it for long. As it is running out of charge the upstream cap is starting to provide charge to keep things going, as THAT cap is running out, the next up the line can take over. This sequence can handle with ease anything the computer can throw at it.

 

For building a power supply feeding an existing digital system (computer etc) you don't have any choice about the lowest level, it is already done. For this system I would use a single solid polymer cap as the output of the supply. The regulator driving that should be a fast regulator, with 10,000uF or so cap at ITS input. The next level up should be a regulator fed by 50,000 to 100,000uF. The first reg does not have to be as fast as the second one.

 

The thermal characteristics of the system are important. If you are running 5A or something you need the raw voltage to be high enough so it doesn't get below the cutoff of the first reg. But the second reg is being fed by a reg so the voltage difference between them can be small. Thus the first reg tends to dissipate quite a bit more heat than the second one.

 

Something like this will be an extremely good source for a computer.

 

John S.

[completeluxury]

john, while you would need some resistors at the regulator for voltage control, would you use resistors anywhere else for emi control etc? a snubber or anything.