Does the quality of mains power effect SQ of SMPS Hifi

People go to great lengths to improve the mains power supply to their Naim equipment, which are usually fitted with transformers and linear voltage regulation.
Dedicated spur, power blocks etc.

Is it worth doing, if the hifi equipment uses SMPS? Or is the quality of mains supply not as much of an issue?

Dear Fatcat,

I have an XS system fed from a powerboard with spike over-voltage protection, no surge protection, and during times of blackouts during storms, I run the house from a 240-volt AUD $500 5.5kva generator from China. There are no separate spurs for the HIFI and no issues. Though all the earths meet at a common point, star earth points are fed from a single power point (GPO).

I find that my NAIM handles any electrical noise issues very well, as I never hear any noise. When the CD5XS or the Linn TT are playing, there is still the inky blackness of no noise between tracks. Others’ experiences may differ.

I hope it works for you. I possibly should point out that we live in a rural country setting. There are a few houses around us and also cows for neighbours.

Warm regards,

Mitch in Oz.

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Thanks Mitch.

It’s good to know inky blackness can be achieved without the HiFi being directly connected to the very nearby electric substation.

I’m surprised I haven’t been inundated with recommendations not to by anything powered by a switch mode power supply.

Well it totally depends on how good the SMPS is. A high end one will perform great.

I’ve stuck the DC out from a cheap SMPS on the oscillascope and all the spikes and dips on the mains still come through sadly. From an EMI perspective though they performed very well.

So, given that mains based noise can traverse the SMPS, I’d assume quality mains is just as important as any other transformer. At least, I can be sure that’s true at the cheap end of the spectrum. I’d not lump all SMPS under the same umbrella though.


Can you say a little bit more about what type of electromagnetic interference you measured?

Certainly. I used an EMI meter to just measure radiated electrical and magnetic fields at a fixed distance in front and above (I think it was 10cm but I don’t recall - easily test again though) the SMPS and compare with other items both hifi and domestic. So Naim power supplies, other audio power supplies, LED ceiling lights, the computer etc. The SMPS had zero magnetic radiation at any distance and low electrical radiation that dropped off sharply. In contrast, linear supplies like those in the Supercap had reasonably high magnetic field (dropping off to near zero Ut beyond a few more centimeters) and near zero electrical fields. Some of our LED lights and the keyboard of the Yamaha electric piano both caused the meter’s “danger” indicator to go off.

I want to be clear I did not measure RF. Transmitted RF meters aren’t too expensive but I don’t have one and not sure how to intelligently interpret those results anyway. An RF band (250MHz or higher) oscillascope measuring RF on signals or mains would be more my speed but they are seriously expensive. My scope doesn’t go near RF band.



Affect? Given that it has been established at least some noise traverses the rectification stage of an SMPS, then the question of affect is really broader and not SMPS related at all. It becomes a more generic question of does mains quality affect power supply performance and therefore sound quality?

I think that topic has had a hundred or so threads. Several of which are still open.

Without reading all the threads about this, it’s a sobering thought that everything we listen to via our systems up to the point it leaves our speakers is mains. :wink:

Not so. It might be modified slightly by character and imperfections of the mains, but what I listen to is music!

I wasn’t questioning the issue. Instead I was pointing out the error in the title of the thread. The verb required in this instance is ‘affect’, not ‘effect’, which is more generally a noun, but can be used as a verb as in ‘to effect a change’.


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As you know I’m considering buying an SL-1200gr, which you advised could be upgraded with linear power supply, as the onboard power supply is SMPS.

So, what I was thinking is this.
Power the SL-1200gr with a 1ph/110v supply from a Hercules power supply, which provides a clean 110v sine-wave.

Perhaps you could remove the slight modification of the sound and imperfection of the mains by switching it off? Oh!..………:thinking:

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Yeah maybe. One user found that the SMPS in the GR leaks audible grain into the ground plane (neutral) on the mains. I can’t comment on that as my GR and StageLine/HCdr are on separate dedicated mains with isolated earth and therefore isolated neutral. If so, swapping out the PSU entirely might be preferable. Apparently it’s dead simple.

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Quality of Mains Power effects everything!


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