Are Smart Plugs noisy?

Any knowledge as to whether ‘smart’ plugs are electrically noisy?

(I mean those mains power sockets that can be activated remotely by Alexa/Siri/Google)

Is the control relay (?) electrically separate from the mains supply it is switching, or do they create noise akin to a switch mode power supply?


Most will use a relay to switch the mains through. As to the wireless connectivity to control the device this will always generate some amount of RF noise. The relay should not in and of itself generate any noise, but I guess like anything in audiophile circles someone will have a different take on the matter.

Bottom line is to try it and if you can perceive a difference that bothers you don’t use it.

Thanks. I had exactly the same thoughts - I asked out of curiosity as I couldn’t find anything online

I’ve got one on my LS50W/REL S3 setup. I only use it via WiFi (I.e. I’m not feeding it with a streamer or anything)

I can’t say I’ve noticed anything detrimental, but to be fair, I mostly have it on in the background.

I use an Isotek power block - if there are any audible nasties, I wonder if that’s catching them?


I used to control my monoblocks with a smart device.

I stopped out of superstition, but I can detect no difference with or without.

Haha, that’s what’s stopping me trying one on my main system :nerd_face:

I use a couple of PS Audio power plants, so it shouldn’t be a problem

It’s dead handy to say ‘Alexa, Speakers’ and have the system on
(and off, when I remember it’s still on and I’m already in bed…)

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…so, along the same lines (quite literally in a couple of cases), do smart bulbs (Hue and LED strips) introduce noise into the mains?

I originally named it ‘KEF System’ but Alexa kept reading Wikipedia Cat pages! :smirk_cat:

I use a Sonoff switch for my main system amp, DAC, and Pi. It feeds a decent non-audiophile surge-protected power board (~$50). I A/B/C’d with the amp straight from the socket, just through the power board, and through the switch plus board. Zero difference.

And now I can say “Hey Siri, play something excellent” and my amp switches on, volume is set, TV turned on and switched to Chromecast, and Roon queues up an album tagged as “excellent”. Which is pretty great. :grinning:

Cool :sunglasses:
The future has finally arrived!

i’m using Fibaro Z-Wave power plugs across the home and have not noticed any negative effect on audio.

However I am not using it for powering audio, but just other components i do not want to be powered when having critical listening session (like TV, HDMI switch, DVD player etc).

I have explicitly chosen Z-Wave as it seemed to me the least RF disturbing technology (e.g. when there is no activity, it send out short signal only once per hour) - unlike WiFi based plugs which usually constantly communicates …
However this is true only for battery powered Z-wave devices - e.g. not the power plugs which are powered from wall :slight_smile: But even those are not very chatty - they transmit mostly when power consumption changes by predefined threshold. But again i can’t hear any negative impact on audio.

I have however observed interesting behavior of those Fibaro smart plugs - even when should be powered off, they probably still pass some current thru, as i can see that some low-power devices are turning on for fraction of second (power led) maybe every few minutes. Ideally i would like that smart plug would galvanicaly disconnect all conductors (e.g. cut off the noise “antenna” from power line) :slight_smile:

Most LED lighting is electrically noisy, some of it alarmingly so. Whether or not that noise couples with your HiFi and affects the sound is another matter, and every domestic installation will be unique in this respect.
Given the large number of light fittings in many homes, I regard it as a matter if good housekeeping to choose electrically quiet devices wherever possible, but that may limit your choice of lighting quite severely.


When we think back to 60w bulbs being normal, having them all over the house, often in multiples to get any decent, yellowish light…


7w, bright, long lasting, multi coloured, remote controlled, voice activated, timed, sensored, seasonal, geofenced etc smart bulbs…

That don’t seem to affect anything else

I’m quite happy

If one is using a smart plug to turn their equipment on/off then I think a worry greater than noise is what does this might do the circuits, etc.

Is it worse to let current flow to a device whose normal switch is already in the on position, i.e is there some mechanism that prevents a damaging spike from occurring when the device’s switch is turned on and is there an absence of such a safeguard when the switch is always left on and the device is activated by closing a smart switch?

Dunno. Maybe a circuit designer like @Sheldon_Stokes or even @wizardofoz would know?

Bearing in mind they’re hardly uncommon, I’ve not heard of any issues affecting connected equipment - have you?

I did see some reports of earlier plugs being unreliable

I thinking that 1) not many people use a smart switch to control their relatively delicate HiFi equipment and 2) that the things that are controlled by such switches are, by virtue of being relatively simple, possibly more immune to such effects.

Pretty sure others will chime in on this. :smirk:

Er, “researched” this…

That’s researched in the sense I’m a layman googler, so roll out the salt barrels

Things that have a shut down routine may not appreciate having abrupt loss of power eg PC shutdown

But they’re able to deal with it

Most stuff is fine, apparently

I hope my HiFi gear isn’t delicate - most of it was bloomin expensive :smiley:

But seriously; power dips, outages, idiot users (I include myself in that demographic) are a consideration of regs and designers on both the consume and supply side of any bits of kit

Dunno about that as there is a robust market in surge suppressors.

The question is whether there is some circuit after the on/off switch that prevents a damaging spike or even if there is a damaging spike.

I remain unconvinced that smart switches aren’t damaging to equipment more sophisticated than a light bulb, e.g…

Really, that’s the reason I took my solid state monoblocks off a switch and never remotely considered putting my tubed pre-amp on a switch.

It’s a fair concern, I agree

Empirically, I’ve been using two for about two years - no drama at all

My original query was about digital noise nasties - and, again, empirically it would seem there are no significant downsides

Technically I’m a mechanical engineer, but I’ve had quite a few EE classes and have some electrical design experience. But there’s got to be more knowledgable folks on here than me when it comes to circuit design.

That said, I can’t think of an example that the internal power switch in a component is doing something fancy that the smart plug wouldn’t. I’m thinking of old-school gear here where the power switch is switching the mains supply, not something computerized where the power switch is really a low voltage logic switch that kicks off the show with a microprocessor (think your computer power switch).

One thing that may be an issue is that a lot of our high end amplifiers have significant power supplies and capacitor banks, that can have significant inrush when the switch is flipped (many tube amps with solid state HV supplies use an inrush limiter, but that seems less common on solid state amps). Designers will typically put a little capacitor across the switch contacts as a snubber to keep arcing across the switch contacts when the switch is opened up (the power transformer is a big inductor and can have significant flyback when the switch is opened at the wrong time in the power line phase). The smart switch may not be expecting such an inductive load and the on-off cycles may degrade the little relay more than was planned by the smart plug designer. But that wouldn’t damage your audio components, you’d just have a dead smart plug sooner than you’d like.