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In Reply to: RE: PSU improvements (part 2): choosing the right picoPSU model and internal wire-type posted by edward on November 02, 2009 at 14:59:44
Hi Edward,I bought a simple Voltcraft 12V/2A inear PSU (40,- euro’s) at www.conrad.nl (part number 510172). I have not enough knowledge nor skills to build my own.
Voltcraft is their home-brand and is produced in Chechoslowakia. But one can buy this type of simple linear PSU’s everywhere. For what is worth: the technical specification shows a max ripple of 2,5 mVolts. But I don’t know if there are any other distortions present on the 12Volt output.As Reylands already suggested it really very easy and simple to connect a linear PSU to the P4 socket if one uses a P4 extension cable. http://www.atxpowersupplies.com/p4-extension-cable-adapter.php . Just cut off one connector and attach that side of the extension cable too the linear PSU and put the other end into the P4 connector on the MoBo. That’s all. This will take you no longer than max 15 minutes. And there you go !
If one P4 extension cable is to short (they are about 14 inch / 36 cm which usually is to short), just use 2 or 3 and connect them together to get the desired length.
But using these handy ready made P4 extension-cables comes at a sonic price as I discovered this weekend. They are constructed with AWG 18 wire. And as inmate Bertel already suggested to me, using low resistance wire (for instance AWG 6 or so) might be far better. And Bertel was o so right !!
If one uses low resistance wire as Bertel suggests, than there’s again a big sound quality improvement.I think many inmates did the same thing like I did, and wired everything together with standard AWG18 wire. So they are not getting the maximum sound quality improvement possible. That’s why I decided to post my findings and encourage other inmates to try the same and report back there findings on sound quality.
Right now I have 2 linear PSU’s outside my pc-case to power the cMP2 PC and 1 standard ‘dirty’ ANTEC Earthwatts ATX PSU mounted inside the PC case. The ANTEC now takes care of the job that originally was indented for the Granite PSU’s.
I don’t like the Granite solution to feed the USB-port, HHD and DVD-drive. When using the Granites one has to bring 230 AC wires inside the PC-case to power these Granites. I don’t like that in terms of noise, hum, RF-polution, etc.
On the other hand I don’t worry very much about ‘horror stories’ on how ‘noisy’ it supposably is inside a PC case. A PC entirely runs on 12/5/3,3 volt DC, so I don’t worry at all about ‘RF-noise’ inside my PC-case. I just don’t like 230 AC wires and unshielded 230 AC -> 12V DC converters inside my case.Having 2 linear PSU’s was not a deliberated choice, it just went this way because I first optimized the power on the P4 pin. I found this to be so rewarding that I decided to also give the P24 a try. So I had to buy second linear PSU 12V/5Amp to feed a picoPSU on the P24 (Using a picoPSU model that leaves the 12V line untouched !)
But when using 1 linear PSU it will have to be a big one because it will have to provide 7 or 8 amp total. May be there is also some benefit from using 2 separate linear PSU’s. They cannot influence each other, ect.
If you buy a linear PSU be sure to buy one with low ripple specs and passive cooling (without a noisy cooling fan).
Furthermore I do suggest that you first carefully read the ‘Advanced’ section chapter 12.b on http://cplay.sourceforge.net/ and their subsequent links to other inmates here on the forum. Some of those inmates are far more knowledgeable than I am. I just read all their recommendations and suggestions and than try something in practice and report back my findings to the forum.
If you don’t mind an extra PSU box beside you PC-case, than a linear PSU on the P4 is a must do. When using P4 extension-cables as suggested by Reylands, you are done within 15 minutes.
It even gets much (!) better, when you don’t use the ready made P4 extension cables (with AWG 18 wire), but when you use low resistance wire (something like AWG 6 wire as Bertel suggests) .Succes and happy listening.
fully AOB optimized cMP2 PC -> Lynx AES16 -> XLR AES/EBU -> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300
Edits: 11/03/09Follow Ups:
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