Continuing the discussion from NDX2 … getting warm?:
SMPS? Something every one here knows and use? Is it possible to choose on or off in this function?
Regards Peter
What’s your concern? The SMPS is disabled once the NDX2 is out of standby and being used.
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If you are using a different source, maybe a turntable with a sensitive phono stage, it’s conceivable that it might be better to turn off the NDX2 completely, i.e. put it in deep sleep mode rather than network standby, of you’re losing sleep over whether there could be nasty stuff emanating from its SMPS.
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Modern quality high frequency SMPS have significantly less ‘stuff’ coming from them say compared to a toroidal transformer saturating or clipping with a tiny amount of DC offset in the mains. If your big transformer is buzzing, it is high likely it’s causing noise on the mains… but I suspect most don’t notice, other than ironically some high quality high frequency SMPS that can be sensitive to that noise.
Cheap very low quality SMPS can cause noise through poor filtering and design, influenced perhaps through cost cutting and cheap components.
I very much doubt Naim use such SMPS modules.
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If SMPS is an issue add an external PSU, then the SMPS is unused as “standby” doesn’t trigger.
XPS-DR will run you £2K.
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Just wanted to know what SMPS do..
I have the ps555 running the NDX2
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Not sure why you’re asking about SMPS then.
You could always ask Google or do an AI search. Or a forum search…
Connecting the external power supply to the rear Burndy socket completely bypasses the NDX2’s internal supplies. Because the unit is then running entirely on the external supply, there is no need to manually disable the internal SMPS
Of course that is AI slop (sourced from THIS FORUM allegedly 
even with a link) because you can’t disable it manually 
What the post actually said…it doesn’t even reference SMPS, isn’t AI wonderful.
But it is unused in your use case as standby is disabled.
Hence zero SMPS noise.
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Indeed, and I chose my words carefully when I said “losing sleep over whether there could be nasty stuff…..” 
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Have a read here about what the SMPS is doing when the NDX2 uses its internal PSU.
This talks about the ND5 XS2 but the same applies to the NDX2 when switching between the SMPS and Linear supply.
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Hi Chris
I have a Rega Aria phono preamplifier sitting on top of my NDX2. Surely that shouldn’t be a problem as I’m powering it from a PS555? Or do you think I should put the NDX2 into standby mode before using the Rega Aria?
P
It doesn’t go into standby mode using the SMPS with an external PSU.
You could power off the 555PSDR and then the NDX2 will be “off”.
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I would expect a phono stage to perform better when isolated from other components, partly because of the potential effects of proximity to live circuits in the streamer (unless its power supply is turned off) but also because of the potential for vibrations when coupled to a high mass object such as an NDX2. So yes, I would at least try putting it on its own shelf. Perhaps just take away the NDX2 and spend a while listening to LPs with the Aria on its own shelf and see if anything improves.
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The problem is that I don’t have a separate shelf for the phono preamp. I’d actually always thought it was enough to put the NDX2 on standby when I’m using the phono preamp.
I guess if it sounds good now you should just leave it as it is. Or if that will always leave you wondering whether your system is optimised you can consider a racking solution in your future plans. Your choice!
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