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Powering a cMP...

The second most-important thing I've learned playing with my cMP over the last 2 years is how important the power supplies are in making a good-sounding piece of audio gear. Even on something like a cMP's computer. Even on seemingly un-important pieces like the harddrive, USB port, and monitor power.

And the third-most important thing I've learned is that most power supplies for computers and other consumer-grade and business-grade electronics are very poor-sounding supplies indeed. They are just not designed with sound-quality in mind.

I think we should consider ourselves lucky that a PicoPSU with a decent 12v raw supply is a considerable sonic upgrade over a consumer-grade computer power supply. Given what I know now, I would not have expected that.

The sound quality provided by a well-implemented PicoPSU strongly suggests to me that a DC-to-DC converter of the type they use does not pollute the outputs and inputs with as much noise as a normal SMPS does starting from a 120v/240v AC input. So there's hope for the Ocean Server solution. But do remember that people have reported that only the non-WI versions of the PicoPSU result in a sonic improvement, so it's only a limited subset of this type of supply... and no guarantee that this is one of them.

I say all this because while I have no direct evidence that would say the Ocean Server DC123SR is a poor-sounding supply, my experience would suggest that it is likely not a good-sounding one. Might be worth a try, but at about $700 for a starter setup (and I suspect you'll want a larger battery), it's an expensive gamble.

Then on the discussion of battery versus AC powered supplies, I am definitely in the camp of those who feel that while a battery supply can sidestep some of the problems inherent in an AC-powered supply, the battery brings it own set of problems and adds a set of constraints on usability. And in my experience, good design can at least largely if not completely mitigate the AC-powered supply problems. So I don't see battery power as a slam-dunk to a superior-sounding power supply. (And the Swenson supply scheme that Ryelands mentioned is one of the most-reasoned and best solutions to overcoming the deficiencies of an AC-powered supply compared to batteries. But for a fully-linear cMP supply with multiple raw supplies, it will be large, heavy, and expensive. I'd also corresponded with the fellow in Australia who had a Swenson-design-based linear supply built for him and it was somewhat of a compromise with just two raw-DC supplies, one powering the 12v P4 and the other the 12v/5v/3.3v ATX-20/24... and it was about as large and heavy as my setup with five seperate raw-DC supplies for the same solution. But I suspect it was very good... and someday I intend to go to that too! But as Ryelands pointed out, I WILL stick with standard EI-core transformers, preferredly split-bobbin to minimize noise transmission. Toroidal transformers are just not as good in this type of application.)


Raymond in Australia's Swenson-based-design linear supply:




My linear supply:




In any case, bottom line is that there's no guarantee that the Ocean Server ATX-20/24 solution will sound good and having it battery-powered won't necessarily make it sound better.

On types of batteries, low output impedance and low noise are important factors in how good any supply sounds, battery or AC sourced. I've heard of others listening tests that strongly agree with Theob's and suggest that LiFePo4 cells sound better than lead-acid or any of the nickel-based cells. See this info from battery-power proponent, Red Wine Audio: http://www.redwineaudio.com/products/lfpv-edition .

I do want to point out that LiFePo4 are a distinctly different cell type from a LiPo battery, which is the soft-packaged cell that most of us have in our cell phones (and that I also use in my high-powered model airplanes). I'm not sure if one of these two types of lithium-based cells are better-sounding than the other... in model airplane use, LiPos are used where the greatest power-to-weight is needed, LiFePo4s where a more economical, sturdier, and safer cell is needed. None of these factors have any bearing on how they sound. Still, the LiFePo4 are a much safer cell type and I'd recommend them to most people over LiPo, even if I saw evidence that the LiPo sounded better (LiPo can violently burst into flame under a lot of conditions, something LiFePo4 don't do as readily). Li-Ion cells (as used in many laptop power supplies) are much lower current cells than either of these two other Lithium types which means a higher output impedance and generally poorer sound.

But this is all in answering your asked question. Your unasked question is 'what's the best bang-for-the-buck real-world solution for powering my cMP setup and getting the best sound I can'. Is this a good summary of your un-asked question?

The two largest improvements I ever heard during my cMP hardware upgrades were 1) upgrading from my modified computer SMPS to the linear P4 supply and the linear/hybrid PicoPSU ATX-20/24 and 2) implementing separate power supplies for my sound card. Even going from the linear-linear/hybrid to a fully linear supply did not produce as large of a sonic improvement (although the fully linear IS a strong improvement over the linear/hybrid, the difference from the modified computer SMPS to the linear/hybrid was greater!)

With this in mind and with your setup where you have a digital crossover and need to use a 'serious' soundcard like the Lynx, I suspect a hybrid-solution might be best. Use a pair of linear supplies with a PicoPSU for the motherboard. And power the Lynx with separate linear supplies, either by using a modified riser-card or modifying the Lynx. The supplies for the Lynx will be pretty simple supplies and can be built-up using a number of available boards and/or kits, such as the Peter Daniel universal power supply board Rick McI mentioned. The key thing is finding a nearby electronics expert to assemble it, modify the riser card or the Lynx, and get it running.

This would not be a 'cheap' solution... but I expect you could do it for no more than and likely less than the Ocean Server solution... and I suspect it would sound much, much better. And if you want to power it via batteries, look at the generic Red Wine Audio supplies... good-sounding batteries plus effective battery management built-in. But this would make it more expensive, of course.

Another alternative would be to use the linear P4 / linear/hybrid PicoPSU ATX-20/24 as above, but add a separate -12v supply to feed the ATX-20/24 that will handle the Lynx current draw. To do this you'd have to bypass the -12v coming out of the PicoPSU and you still might need a local electronics expert, just less of him. Still, you'd be getting your 5v, 12v, and -12v for the Lynx from the motherboard and that's a BAAADDDD source for good sound. It would work, but definitely not sound as good as the separate supplies for the Lynx.

Oh, finally, the most important thing I've learned in the past 2 years? That I honestly know almost nothing about designing good-sounding power supplies and that any sonic improvements I've gotten from all of my power upgrades have been more luck than intent.

My 2 cents!

Greg in Mississippi

P.S. The main driving force for the development and commercialization of LiFePo4 cells is their use in cordless power tools... and for many hobbyists like myself, the least-expensive way to obtain them is to buy an appropriate power-tool spare pack when it's on sale and take it apart!


Everything matters!


Edits: 01/27/11
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