Do Switched Mode Power Supplies (SMPS) around the house corrupt Hi fi performance

[bumpy]

I keep reading how household SMPSs corrupt the electrical mains and this can influence the SQ of Hi Fi systems.

I have just had a quick count up and my house has over 20 SMPS plugged into the mains most of the day and an untold number inside various bits of kit.

Is this a problem and are there solutions?

Thanks

[Mr. C]

I would suggest in may ways they can and do have effects on many devices not just audio

[Firebottle]

That's a tricky one to answer. Or rather there isn't a fit all answer.

Based on experience any audio equipment that includes a SMPS can be improved by replacing with a linear PSU. I have done this on numerous pieces of kit.
However the subjective improvement will depend on the overall 'quality' of the complete hi-fi system.

Whether SMPS's external to the hi-fi system have influence on the SQ depends again on the 'quality' of the audio equipment and if there is adequate separation of mains input and audio circuitry. Plus whether any internal filtering is present.
Disconnection of external SMPS's is the approach to see if SQ is degraded.

Replacing all SMPS's with linear PSU's will of course remove all the noise from SMPS's but could prove very expensive, even if possible with all the variations.

[Macca]

my view is that any interference problem will manifest itself as obvious buzz, hum or hiss, it won't manifest as reduced sound quality.

That will depend on the PSRR of the equipment you use. https://en.wikipedia.org/wiki/Power_...ejection_ratio

As long as it's well engineered mains noise will have no effect. If it's not you will get obvious issues, not slightly less focused sound of second violin.

I've yet to see any evidence to the contrary.

[bumpy]

my view is that any interference problem will manifest itself as obvious buzz, hum or hiss, it won't manifest as reduced sound quality.

That will depend on the PSRR of the equipment you use. https://en.wikipedia.org/wiki/Power_...ejection_ratio

As long as it's well engineered mains noise will have no effect. If it's not you will get obvious issues, not slightly less focused sound of second violin.

I've yet to see any evidence to the contrary.

Forgive me if I misunderstand, but I think you are saying that if you plug an SMPS alongside a bit of hi fi kit in a double mains socket it shouldn’t have any effect on the hi fi device. If this is the case, why the general trend to convert SMPS to linear power supplies?
I could pose the question where is the evidence to show there is no effect on hi fi SQ by SMPSs on the same mains circuit.

[Macca]

Forgive me if I misunderstand, but I think you are saying that if you plug an SMPS alongside a bit of hi fi kit in a double mains socket it shouldn’t have any effect on the hi fi device. If this is the case, why the general trend to convert SMPS to linear power supplies?

power supply in a unit can bleed noise into the audio signal and that will give worse sound quality if there's enough of it. So you could conceivably make a difference with a different power supply to the unit - you can get noisy SMPS and noisy linear supplies.

Properly implemented SMPS power supplies can be quieter than LPS they are not intrinsically bad. And also internal layout can matter so fixing a problem there can help - which might be a side-effect of changing the PS.

But that's not the same as 'noise on the mains' caused by another device plugged in somewhere else. Like a buzz through the speakers when a refrigerator motor kicks on.

Go with the advice given - turn off all SMPS devices in the house, see if you hear better quality sound.

I tried this some years back, made no difference, but I only had 4 devices with SMPS so some may argue that wasn't enough to matter.

[bumpy]

Thanks Martin

[bumpy]

I was thinking again about 'dirty' mains and remembered that most exhibitors at hi fi shows are concerned at the poor mains quality caused by hi fi kit in nearby rooms.

Equally turning off SMPSs in my house could only be part of the cure. Every other house on the power feed to our area could be part of the problem.

[bumpy]

OK

I have just turned off all the accessible SMPSs in the house (about 20). This includes such things as three Alexas, six phone chargers, iPad chargers, computer anxillaries etc. I doubt any great care has been taken in their design in terms of mains polution.

I stopped at visiting all my neighbours asking them to go dark.

There is a marked decrease in what I describe as a slight glare to the sound, making the hi fi more listenable. This is exactly the area I want to improve, is very encouraging, and directs me towards a way to eradicate that mains noise. I forgot to listen out for tansformer hum or random noise in the speakers as I was so please with the improvements to overall SQ

[Jimbo]

OK

I have just turned off all the accessible SMPSs in the house (about 20). This includes such things as three Alexas, six phone chargers, iPad chargers, computer anxillaries etc. I doubt any great care has been taken in their design in terms of mains polution.

I stopped at visiting all my neighbours asking them to go dark.

There is a marked decrease in what I describe as a slight glare to the sound, making the hi fi more listenable. This is exactly the area I want to improve, is very encouraging, and directs me towards a way to eradicate that mains noise. I forgot to listen out for tansformer hum or random noise in the speakers as I was so please with the improvements to overall SQ

Don't forget to switch off your Christmas tree lights - these are extremely noisy on the mains!