Linear ATX Power Supply

Are there companies that build linear ATX power supplies. I have seen Core Audio Technologies advertise on Agon, but are there other manufacturers?

I have Googled but sources seem scarce beyond DIY and bench style linear supplies.
I assume that is a no.

Since there doesn't appear to many companies offering this, the demand must not be there. Curious to know what others are doing for your pc based music servers?
I've never heard of one. Computer power supply is regulated. To reproduce it in linear fashion it would have to operate at minimum line voltage and be able to take max line voltage. Since there is perhaps 20% difference between max and min linear regulators would have to dissipate about 20% of rated power. For 300W supply it would be 60W. Taking other losses into account it would be close to 100W. Removing that much heat, even with a fan in small cage seems impossible especially if you take into account space needed for capacitors and large transformer since transformers operating at high switcher frequency are 10 times smaller.

I assume that your intention is to reduce jitter on digital out. The best solution would be to reclock before DAC or use transfer method that removes timing (Ethernet, Wireless etc) and then reclock only if necessary. Good computer audio board most likely will have own supply that is isolated (floating) but I don't have much experience with audio cards.
Thanks for the response. You are correct that it would be difficult to fit a linear supply into a regular ATX supply case. I should have just asked if anyone knows of a linear ps solution for PC based system. No problem having the ps in an external case.

I like the solution provided by Core Audio Technology, but wondering if there are other companies as well.
My brother just created a PC based server that uses Core Audio's kora power supply. Its a PC made only for music, you can surf the web but nothing else. He used an Atom based processor/MB and a specialty USB card. The PC is tiny and has no fans at all. I must say it sounds really good. He had the mac/mini and kora power supply before but liked the PC based server's sound better.

The kora power supply could power the PC no problem. Its just not a powerful computer for gaming or graphics, but if all your doing is building a music server than it is top notch.
Thanks Runmeshaw.

I also use a PC based server with good results and the linear ps is one of the final tweaks that I would like to make. Problem has been finding a clean solution that wouldn't look out of place in an audio room.

I am concerned about the customer feedback on Core Audio and looking for an alternative, but there doesn't appear to be any. I am surprised there aren't more audiophiles who are looking for this type of product.

Have been trying to convince Gilbert Yeung of Blue Circle to build a custom ps but they are just too busy. I have suggested that there maybe be a demand for this type of product, but it doesn't really appear that way.

Here are some for the Mac Mini!product/prd1/667867321/mpsu
Unfortunately I need a ps that conforms to the ATX spec.
Hi All,

My name is Ryan Mintz and the ATX Linear Power Supply is my design that I have been working on with my engineers now for close to 8 months. It has gone through SEVERAL revisions in that time and is a pretty neat device.

Kijanki is correct, it's not possible to build a linear power supply into a tiny ATX spec box -- sort of.

In our ATX Linear supplies we divide it into two separate boxes. The external box is larger and houses the transformers, AC Filtration, rectifiers, and bulk capacitance (720kuF in the S2).

The internal chassis fits in a standard ATX slot, screws right in and has a standard ATX wire harness for connecting to a motherboard.

The internal board handles the logic circuitry (PSON, PowerGood, Overvoltage, undervoltage, over current, over temperature protection) and is a 9-rail linear power supply. -12V, 3.3V, 5V, 5Vsby, 12V1, 12V2, 12V3, 12V4, 12V5. It uses 12 transistors capable of sourcing a 25A load each. At low current loads the fan doesn't run as the heatsinking and power sharing between transistors is adequate to dissipate the power.

The design uses a supervisory circuit for power management, and that is linked through a logic inverter to enable our regulation circuitry. The regulators are our same design used in the New (as of the end of April) Kalos power supplies with very fast transient response, wide bandwidth, and less than 3uV output noise (you can see the pictures of the Kora on our website).

Special focus was given to the 3.3V rails in terms of current and noise floor. The 3.3V rail is responsible for powering PCIe/AGP, logic circuitry on the motherboard, low voltage CPU regulators, and the chipsets -- this means the 3.3V rail (not the 12V rail) is by far the most important to your sound quality.

We do very high-end Mac Mini systems as well and they sound very good. The biggest limitation here is the DC-DC conversion on the logic board itself. Our logic board shielding helps to absorb much of the EMI here, but that's still going to be the limiting factor if you're looking for ultra high-end performance. The Mojo supplies are good, though not a fan of the LT1083 he still uses in his latest design, it's too slow and noisy. Regardless, the power supplies are still a great upgrade, you can't go wrong with any of the power supplies that are popping up on the market these days. They're all tremendous upgrades for the Mac Mini, though some better than others of course.

I have a async USB DAC with galvanic isolation (Wyred DAC2SE),
and I am using a Wireworld Platinum USB cable with further isolation of the noisy DC pins on the USB.

Would I still get an improvement with a linear supply if I am using async USB from a Mac Mini with this setup?

Galvanic isolation on the USB input of your DAC is good thing to have, however, it is by far not enough to receive clean signal into your DAC. This is because the data stream your DAC get is already "spoiled" by one ot another degree by the quality of the power supplies supporting your server. Also, as Ryan Mintz of Core Audio correctly noted above, the DC:DC convertors, as a rule, degrade substantially improvments produced by high quality power supply. Thus, handling of electrical signal is paramount in music servers, and we at Musica Pristina pay enpurmous attention to it.

I would add that high quality software environment plays equally important role in resulitng sound quality but its the outside the scope of this discussion.

All The Best,

Simon Thacher
Musica Pristina $1350.OO