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Hi all,
I am like many of you interested in building the best possible computer transport. In my case, for the time being I will be using my dedicated PC with RME PCI s/c as analog-out source, thus good PC configuration becomes even more important.
The PC I am building will be totally minimalistic and fanless, based on ultra low voltage VIA C3 600Mhz system, SSD hard drive and custom-built case, with separate isolated sections for PCI soundcard and psu. (Though I've read 'The Art of Making Computer Transports', I still don't get why his choice was Biostar mobo.. I'm IT enthusiast for quite some time already, and Biostar mobos, at least since 10 years ago, were regarded as cheap low quality stuff; besides, if there is a need for some CPU power, the suggested system could have been e.g. socket 479 based mobo+Pentium M Dothan clocked at 1st step=600MHz). Anyway.
I was asked by one forum member to share my findings about the PSU that I recently ordered from Canada on Ebay. I was going to buy the PicoPSU and feed it with the linear bench PSU. However, the guys who specialize in electronics and diy stuff convinced me that there would be no use to use PicoPSU+linear feed. It is because on the one hand, PicoPSU is by itself a switching mode PSU, while on the other hand, even if I managed to feed the mainboard with linear power source, the mainboard itself employs like 4-level switching mode power distribution, what would in principle defeat the purpose of using linear source.
Having all this in mind, I started looking for the lowest ripple and best quality switching mode PSU. After reading many reviews, I came across this little thingie:
http://cgi.ebay.ca/130W-mini-ITX-ATX-Power-DC-DC-converter-RoHS-PicoPSU-Y2_W0QQitemZ180425806870QQcmdZViewItemQQptZPCA_UPS?hash=item2a02375416
I asked the seller Electrodacus to compare his product with the PicoPSU,
and he had this to say:
'This PSU have a lower than 16mV ripple on all lines an uses 3x1000uF on all important lines 12V ,5V and 3.3V all have 3000uF each + each DC-DC converter is using another 2000uF 2x1000uF and coil at the input.
Maybe you want to see this review at SPCR http://www.silentpcreview.com/Winmate_DD-24AX
PicoPSU only produces 5V and 3.3V on board and uses the 12V directly from the Ac adapter so it will be extremely noisy and because of the size the capacitors on 5V and 3.3V are limited to under 500uF this is almost 10x less'.
Based on my research on PC psu's, this looked like the best choice for me, thus I ordered it yesterday. I will try to compare that PSU with my Corsair HX-450 (which appears to be one of the best 'mainstream' pc psu's available), and will report my findings here as soon as I build my rig. I will use it with my original Sony 19.5V@4.1A power brick, which came together with my laptop. <16mV ripple is almost like the ripple on linear lab psu's, thus I'm very curious about this.
D,
Though I've read 'The Art of Making Computer Transports', I still don't get why his choice was Biostar mobo.
That was a long long time ago. Current rec is a gigabyte board and the cMP2 build uses this with the e7400 processor with undervolting and underclocking.
Anyhow the combo cics recommends produces better results than I ever got from my via c3 1ghz processor. Though I didnt do many of the os optimizations with it. Both though are totally fanless.
Good luck on your experiments.
I think Electrodacus's comments point out one of the things that makes the PicoPSU work pretty well in this application:
"... PicoPSU only produces 5V and 3.3V on board and uses the 12V directly from the Ac adapter..."
The key is to use a good power supply for the 12v. I'd never recommend using the PicoPSU with a SMPS supplying the 12v in an application looking for good sound... but with a good regulated 12v supply, the PicoPSU is a good easy-to-implement solution. I suspect a better sounding solution is the heroic 'separate linear or battery supply for each voltage' solutions... see details in the cMP or cPlay threads, sorry, don't remember which. These will sound the best, but take a lot of DIY acumen.
I also totally agree with FMAK on the PicoPSU's advantage of minimizing the wiring (less radiated RF) and the advantages of lowering the number of switching supplies... best of course would be none!
Greg in Mississippi
P.S. See hfavandepas's recent posts on PicoPSU's & wiring in the cPlay thread for more.
1. cics could respond in more details, but one of the reasons for Biostar mobo was its BIOS settings flexibility. Anyway, his recommendations for cMP builds since moved on to different mobo (Gigabyte) and different CPU (e7200/7300).
2. In case of quality linear PS feeding PicoPSU, 12V directly from the PS is actually a big plus, not disadvantage - and I'd risk to guess, much better than what Winmate could muster.
3. (related to #2): 16mV ripple is NOTHING like quality bench linear PS. Look at these specs here, for instance:
Specification for Topward 6000 Analog DC Power Supply
...
Ripple & Noise CV <0.5mVrms @ 100W; <1mVrms @ above 100W
...
That Topward 6000 psu is > 400$...
The question remains - why use linear supply, if the mobo itself involves switching?
'cause 2 swirchers make things worse!
for good reasons to stay away from the Winmate.
"We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines." N.P.
why bother using a non-standard supply like the "Winmate" when *much better* standard ATX switching PSUs are available? FYI, the recommended cMP ATX PSU, Antec EA430, has a measured ripple of 6mV.And the obvious answer to your question: because a computer powered by (even if only partially) linear supplies is "sonically" superior than its SMPS-powered counterpart!
Why else? Convenience, less heat emission, or 80plus efficiency?
"We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines." N.P.
Edits: 11/03/09
I agree that the key is listening. Anyway it's 30 bucks and fanless, I will do some testing against Corsair when I receive it, using k701+Shanling P100. Probably gonna buy PicoPSU + borrow linear supply as well for testing.
Btw, where can I get this updated version of 'Art of building pc transports'? I have v0.3, year 2007 so it's pretty outdated.
See link for the updated official documentation. I also strongly recommend you to go through the massive cPlay and cMP threads on this forum.
"We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines." N.P.
N/T
Don't use a 600 Mhz chip; the ME6000 uses nearly 60% cpu resources playing 192k files with nothing installed. The Atom 270/330 boards are better although you will need to ventilate well and increase heat sink surface area.
The pico boards score because there are no dangling wires and because the good one use decent low DA capacitors. You can add additional capacitance to get the various impulsive modulations down to low levels.
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