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In Reply to: RE: cMP - the open source high-end Memory Player posted by cics on December 30, 2007 at 05:42:01
For those reading this post, who haven't read cic's post on this, here is a link.
cic's 2 ATX post
I believe I know the answer to the first two questions but, that is when I usually get in to trouble.
It there anything problematic with completing the optimizations using one power supply and then adding the second?
Once the optimizations are complete should I defeat the PSU's cooling fan? How do I accomplish that?
Can I snip off and insulate the rest of the wiring of the "Clean" PSU?
(leaving just P24)
What is the preferred method and sizes of implementing bypass caps on P24 and P4?
Your help is much appreciated!!
Julien
"There's someone in my head, but it's not me"
Follow Ups:
I will probably move to linear supplies eventually, when funds allow.
I thought that someone might be using bypass/de-coupling caps at the plugs to shunt high freq junk that could be picked up by wires in the pretty hostile environment inside a PC.
I did a couple of preliminary searches but didn't find anything. I do see how adding some more capacitance to each line would further reduce ripple current but wouldn't help remove junk picked up by the wires feeding the MoBo.
Do you have any thoughts on this matter??
Thanks again for responding!
Julien
"There's someone in my head, but it's not me"
Julian,
Sorry, I missed this post earlier.
This was discussed about 1 1/2 years ago in the cMP mega-thread... see here:
http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=42455
I tried this with my Antec 430 computer power supply & found very useful sound quality improvements... but also found an 'edge' to the high frequencies that I guess was the signature sound of the Panansonic caps I was using. When it didn't go away with break-in, I then tried the linear-powered PicoPSU solution discussed here:
http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=47156
and the linear supplies for my HDD, screen, and USB's discussed here:
http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=48848
I realized that while adding bypass caps at the computer power supply power plug is a worthwhile upgrade, the added performance of linear-hybrid or fully-linear supplies is so MUCH higher that adding caps on the ATX-24 and P4 plugs only make sense if you are severely cost-limited or ability-limited. Or in other words, if you can solder well enough to add caps to the plugs, you can assemble the linear-hybrid supplies.
My 2 cents.
Greg in Mississippi
Everything matters!
Julian,No problem in doing the optimizations with one PS & then adding a 2nd. In fact, I suggest that... build up your cMP with the stock CPU heatsink & a nearly stock PS and then convert to fanless and do PS mods after you have a stable, low-voltage, under-clocked setup that is running well (and that you have backed-up!).
Another tip that might not be in the cMP doc is to do the basic BIOS optimizations (disabling un-needed devices, etc) when you first power up the board before installing WinXP... do everything EXCEPT disabling the overtemp protections and lowering the CPU voltage to the ultimate level (keep it at about 1.0v). If you do this, WinXP won't see any of the un-needed peripherals and you won't have to un-install them and related software and drivers later.
On disabling the fan on the PS, in the Antec it is just plugged into the main board, so disabling it is just a matter of un-plugging it.
On removing the excess wires, if you are going to clip them, it is best to do it very close to where they are soldered on the board... otherwise the stubs can still act as antenna. But best in my mind is to unsolder them... not too hard of a job if you have at least basic soldering skills.
Finally, 1,000uf-10,000uf of caps across each voltage (not voltage line... several of the voltages have multiple lines to increase the current capacity) should be safe. Much less doesn't provide much benefit... much more and you risk damaging the PS at startup. Others may have different opinions here.
Greg in Mississippi
Everything matters!
Edits: 07/18/10
Hi Julien
> > It there anything problematic with completing the optimizations using one
power supply and then adding the second?
No, there shouldn't be any problem. I did just that.
> > Once the optimizations are complete should I defeat the PSU's cooling
fan? How do I accomplish that?
Yes, and if you are using Antec, just unplug the two pins socket and remove the four screws to physically remove the fan as well.
> > Can I snip off and insulate the rest of the wiring of the "Clean" PSU?
You should get a modular PSU. In this case, it would be easier to remove the unwanted cables. For me I de-soldered those not required anymore.
I had switched to linear supply for the CPU and hybrid linear and PICO PSU for the mobo, and I can say that switching back to SMPS makes my system not listenable.
HTH
HTH
HTH,
You wrote:
> > > I had switched to linear supply for the CPU and hybrid linear and PICO PSU for the mobo...
Did you build up linear supplies or buy them? If you bought them, which ones?
THANKS!
Greg in Mississippi
Everything matters!
Hi Greg
I am using 2 numbers, off the shelves linear power supply from Mouser Electronics.
Sola/Hevi-Duty SLD-12-6034-05T(12V & 5V) for CPU and other devices.
Sola/Hevi-Duty SLS-12-034T powering the 150W Pico for the mobo.
These are run on separate lines. Power inlet are through Bulgin IEC BZH01/Z0000/01(with switch and fuse). Used of these power inlets with Hi-Fi tuning fuses yield a better sound than direct connection to wall socket , the most evident was the tactile sensation in the bass not previously encountered.
These might not be the best but have to make do for the moment pending a better build. But I had ran these continuously for 40 hours without any problem.
Hi Greg
I am using 2 numbers, off the shelves linear power supply from Mouser Electronics.
Sola/Hevi-Duty SLD-12-6034-05T(12V & 5V) for CPU and other devices.
Sola/Hevi-Duty SLS-12-034T powering the 150W Pico for the mobo.
These are run on separate lines. Power inlet are through Bulgin IEC BZH01/Z0000/01(with switch and fuse). Used of these power inlets with Hi-Fi tuning fuses yield a better sound than direct connection to wall socket , the most evident was the tactile sensation in the bass not previously encountered.
These might not be the best but have to make do for the moment pending a better build. But I had ran these continuously for 40 hours without any problem.
Thanks. I've been looking at commercial linear supplies to use as the basis for an easy fully linear setup... WOAH, these things are expensive!
While my home-built linears don't have much less cost in materials, I can use very premium parts (Jensen 4-pole capacitors, good soft-recovery diodes) in them... and my experiences so far strongly say that sound quality is related to the quality of the supply and it's parts.
I was surprised when I heard the sonic signature I associate with various capacitor types (Elna Silmec, Panasonic FM and FC) when they were used on either the computer supplies or the 'dirty' (harddrive, USB, and screen) supplies. I don't have an explanation for this, but the sonic results were clear.
Still, a commercial linear setup may useful.
Greg in Mississippi
Everything matters!
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