The switched PSU chirps

I have a chirping SMPS as well, I have a green solo and a green reflex and one smps is noisier than the other. It is not the solo or relex it is definately the SMPS.

Curiously I am decorating at the moment and have unplugged everything for a week or so and have plugged them back in so I can listen my CD player through the solo and the chirping does not seem as loud. I will check back tomorrow.

One SMPS has tone you can hear with your ear next to it but the other has a louder tone which is lower in frequency than the other, and less 'pure' and louder. It seems to be an occilating frequency (does that come under 'you don't say banner'?). It doesn't matter if I plug the SMPS directly in a wall socket or in a surge protected strip block.

I have tried it in a mains wall socket and a surge protected mains block which may have some filtering in it, it's one of those cheap ones from maplins or somewhere (lost in the dim regions of time).

I will try and pop it in the post this week since my HiFi is in bits.


I have kept up the chirping phrase on the basis that it is trying to describe the audible noise (from more than a few feet) from the smps as I have tried to say above it does seem to be some high frequency vibration from inside the device but it is not a constant single tone.

Fritz and Serverbaboon, my appologize , I thought you were talking up strictly on power up.

Hi all,

We had some back from Serverbaboon the other day, and it looks like the main thing the EU hasn't considered is the high pitched emissions of SM-PS. True, the one in your computer doesn't do the same audibly (maybe your dog is being driven wild by it...) but that's because it's big and butch! (I didn't mean your dog, unless that is, he's big and called butch).

The plug top variety mostly suffers the same problem as the energy saving light bulb - they run at just above 20kHz, which means along with other normal sounds in a household, you'll hear them at a lower frequency caused by a thing called "beating". As I've explained countless times, beat frequencies are set up in all walks of life - it's the reason why your car engine seems to emit a throbbing or wobbling sound in traffic jams - it's even why Steve McQueen's motorbike spokes seem to show the wheels revolving in the wrong direction in "The Great Escape". Apart from doing a super high frequency SM-PS of the type used in computers, which would "cost the earth" in world-wide approvals packaged as an external power supply (but hey, I guess some manufacturers don't give a toss about safety, energy efficiency limits and EMC rules - but we have to because there are plenty of people willing to blab on us), we are stuck with little plug top switchers that sing.

The younger you are the more you'll hear the high frequency whine that sounds similar to a flash gun charging. In some circumstances the sound can be a chirping - it all depends on the many sounds surrounding you and your own hearing sensitivity. The only way I know how to remove the sound is to place the SM-PS in a bell jar and attach a vacuum pump to it and evacuate all the air - what a jolly good idea for the latest Slee product