Power Supplies

The new linear PSU that provides 400 watts / Power Supplies for the Baetis® Media Computers / LiFePO4 battery-based PSUs versus the very best linear PSUs


The new linear PSU that provides 400 watts

Well, we finally found the only linear PSU that a) sounds better than our previous switch-mode supplies and b) provides enough power to our media computers to play anything and everything without becoming too hot to the touch. None of the brand-name linear models we had previously tried met either of these objectives.

Introducing the HD-Plex™ 400 watt linear PSU. This unit is now standard on our Reference 2 and available for any of our Baetis computers that have the Neutrik DC input on the rear of the chassis. It has enough power to, say, allow JRiver to transcode DSD to PCM on the fly for hours and hours, or play several 4K movies in a row, without overheating. The audio in 2-channel has slightly more detail plus more presence. We think the majority of Baetis-model owners will want this new linear PSU. With our Revelation™ Audio cryo-treated-silver DC cable, this is the very best AC-DC converter in the world, we believe.

Ripple noise is less than on our latest Baetis model, but even more important, there are 4 separate, isolated outputs, including a variable voltage output (all of which are Neutrik™ XLR connectors). The Neutrik XLR connectors are provided by the manufacturer specially for Baetis. Thus, this model can be used to power separately, the computer itself plus, say, an nVidia™ highest-resolution video card. Or, it can power the Baetis plus one of the top USB outputs (think SotM™’s latest non-PCI-bus model). Whenever you use a PCI card, there is more inherent common-mode noise that can only be minimized via an isolated external power supply. Our new Custom Shop will be glad to talk with you about these possibilities. [Thanks to Chris Connaker of Computer Audiophile for introducing us to these great PSUs.]

HD-Plex Linear PSU

Price $1,550, including our Revelation Audio™ cryo-silver DC cable.

Dimensions: 12.6" L x 9.3" W x 3.9" H; 22lbs

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Power Supplies for the Baetis® Media Computers

It goes without saying that the true audiophile (or videophile) is concerned about the quality of the 12 volt power going into his various components, just as he is concerned about the AC power going into his expensive amplifiers. One of our build philosophies is always to place the AC/DC conversion unit, or Power Supply Unit ("PSU"), outside of the computer’s chassis, to minimize EMI/RFI. EMI can be minimized most effectively by surrounding the offending component with metal and, therefore, we simply won’t allow our servers to be an all-in-the-one-box solution.

There are many, many PSUs to choose from, and we are appalled by the quality of some of the PSUs we see attached to very expensive brand- name audiophile components, including music servers. In the music servers we auditioned, we were able to hear significant audio improvement going from a generic switch-mode PSU with 60mV of ripple/noise to one with 20mV of noise. Our own computers come standard with a PSU that has, at the least, a stable Kycon 4-pin connector, not the usual "wall-wart" barrel connector, and its measured ripple/noise is 10mV. Again, you can hear the improvement in audio quality – darker backgrounds, more space between the instruments, more life-like sound.

Before we get to our discussion of non-switch-mode PSUs, you should also know that many of the expensive battery-based or linear PSUs we tried did NOT sound at all better when compared to our standard switch-mode supply, when our PSU is plugged into a special UPS. We started using a pure sine-wave uninterruptible power supply ("UPS") with voltage-variation control very early on, because we knew that no computer likes to lose power suddenly. Moreover, our very sensitive motherboards were affected by voltage drops as well as voltage surges.

But we had heard from some experts that an UPS had a negative effect on audio quality. We did not hear such an effect on audio quality when the UPS is producing a pure sine wave AC signal. And when this pure sine wave AC signal was tightly voltage-controlled, the PSU itself became less problematic. Thus, we now require our Baetis computers to be used with the CyberPower® 850 VA UPS model number CP850PFCLCD. [Note: There is a corresponding model for 240v AC in other countries.] We ship this UPS to the customer with each Baetis computer; the client MUST purchase this UPS with certain of the Prodigy series.

This is more than enough AC current for any computer we build now or in the future. And it improves audio quality, not degrades it!

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But what about the LiFePO4 battery-based PSUs versus the very best linear PSUs?

We have solidified our mind set about battery-based PSUs and linear PSUs over the last 2 years or so. These PSUs really do provide significant improvement in sound quality compared to the "wall wart" PSUs that come with many brands of computers and DACs. But only the new HD-Plex linear PSUs beat our UPS/PSU two-box combination. Nevertheless, because some clients will have a $3k or $4k PSU that they may wish to use with our servers, we now include in our top models, a special Neutrik DC input connector for use with these expensive PSUs. You ship your PSU to us and we change the simple barrel connector to the better Neutrik DC connector, test it, and ship it back to you. We think you should sell your PSU on Audiogon and use the proceeds to buy a better digital cable, but we understand how the audiophile industry is prone to certain ways of thinking. We want to make the customer happy, but in no case will we allow a Baetis computer to be used with any PSU that is NOT plugged into our special UPS (if you do so, the warranty is voided). Below we have a brief discussion for you regarding LiFePO4 PSUs,

  1. No PSU is free of ripple, nor is any PSU free of output noise measured as micro-volts. The most important specifications of a PSU, according to our friends who are experts in this industry, are output noise, output impedance, and bandwidth.
  2. The output noise measurements in the LiFePO4 battery-based supplies (which are deemed to be better than the old Lithium-Ion batteries) are lower than switch-mode supplies but not necessarily lower than the very best linear PSUs.
  3. As the battery drains, its output noise changes to higher frequencies; and this requires much more care in regulation and filtering.
  4. The battery packs are not connected to ground in the same manner as a switch-mode or linear PSU. This presents the potential for common-mode noise, however small, in the user’s system.
  5. Batteries can’t be recharged forever and their expected life can be significantly less than the very best linear supplies.
  6. If the computer/server using the AC-DC converter rips and plays blu-ray media, the wattage demands can be relatively high for significant periods of time. This implies the need for larger battery-packs that are both more expensive and require more frequent recharging. These packs have the same limitations of smaller packs.

Linear PSUs, meanwhile, do not have most of these shortcomings and typically are somewhat less expensive than the LiFePO4 PSUs; and the very best of them are completely quiet. However, all but one of these linear PSUs also suffer from the same problem of too low DC amperage. This is because they typically are designed for simple “music only” servers or computers, including the factory Macs and PCs. When you start to use our computer for, say, transcoding a large DSD file on the fly into WAV, this CPU-intensive job can cause the linear PSU to become quite hot to the touch. Not a good thing for longevity.

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