Vinnie-
Here's a quote from a poster at computeraudiophile.com about LIO: In other words, he's saying the SMPS will inject noise back into the other components in a system over the common mains supply. I'd like to hear your comment, I'm guessing you'll tell us why he's mistaken.
Hi firedog,
My quick reply is this: I do not think that poster on CA is mistaken. But if a power supply that "kicks back" low amounts of noise on the AC line is used, and if other audio components on the AC line have decent power supply / regulation, it should not be an issue. That is on the AC side of things. On the DC side of things, I would avoid using SMPS, and avoid having the AC/DC conversion inside the audio component (unless it could be well-shielded). In the case of LIO and its internal components, it makes no difference if an SMPS or Linear supply is used for AC/DC conversion, nor does the noise level / quality of the mains power matter to LIO due to its internal ultracapacitor bank (PURE-DC-4EVR) topology.
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My longer reply goes something like this: I do not think that poster on CA is mistaken. All SMPS generate 'some' level of noise (not much in terms of low freq. hum, but ultrasonic noise in the hundreds of kHz range, typically). Some inject tons!
Others inject very little. LIO's power supply injects very little (even less than the Red Wine Audio SLA and LiFePO4 battery chargers over the years outputted). It uses common-mode choke filtering on the mains input, and this cuts down on a lot of the noise feedback onto the mains.
A 24V, 5A
linear power supply would most likely be cleaner in that there would not be ultrasonic artifacts feeding back to the mains. Not sure you would be able to hear the difference (it really depends on how sensitive your other gear is to mains noise - see below), but it would be larger, heavier, more expensive, and run hotter. Without a fan on it (
), it would need a decent amount of heat sinking.
SMPS plugpacks in general, inject a lot of noise back into the mains supply which often degrades performance of low level devices such as DACs etc.
Well, the LIO's dac (and ALL LIO's components / options) will not see any noise from the AC mains. LIO does
not care one bit about noise on the mains, because LIO is always isolated from the mains. You could have the best power conditioner, dedicated mains, power cords, outlets, etc - it will not matter at all to LIO.
Other brands of components on the AC mains should/better be able to filter out (to negligible levels) the small amounts of noise that LIO's charger kicks back onto the mains. I would think in many circumstances, the mains themselves have more noise on them already than what LIO's charger adds. Noise from things such as the SMPS from computers, cellphone/tablet chargers, music servers, TV's (nasty kickback!), noise from appliances, energy-efficient fluorescent and LED light bulbs, etc. all add a lot of crap on the mains. No doubt about it!
Using power filters / conditioners for those other audio components that run off the mains should help with all of that (if needed).
Also, it is important to note that SMPS's (and even linear power supplies) tend to radiate noise. This is why I believe getting the power supply (the AC to DC conversion process) OUTSIDE of the audio component is a very good idea.
With LIO, the power feed into it is already converted to DC
externally in the power supply. So the mains voltage, and the AC/DC conversion (transformers, rectifiers) can be located feet/meters away from the LIO and other audio components. But I certainly can take no credit for coming up with the idea of separating power supplies from the audio component's enclosure.
Vinnie
