Can one hear a switching power supply?

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I dont see why a headphone amp would make a switching ps economical to use.
Yes you CAN hear a SPS. I have an LED globe which makes so much EMI (either conducted or radiated) it make AM radio reception practically impossible.
Its a little discussed topic but makes the argument for retaining incandescent globes acceptable IMHO.
 
I am DIYing a headphone amp with a LDO regulator which has lower PSRR than regular regulators, can it effectively filter out the broadband noise generated by the switching P/S?

I think LDO will help, but not much. I posted similar question before, I remember the answer is to use LC or beads after the LDO.
 
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If it is done right NO.
Yes you CAN hear a SPS. I have an LED globe which makes so much EMI (either conducted or radiated) it make AM radio reception practically impossible.
Its a little discussed topic but makes the argument for retaining incandescent globes acceptable IMHO.
I presume this is a little chhepp thing, that by the sounds of it has not been through any EMC testing, so you cannot use it as a global example of SMPS and SMPS designs.
I have done a board with two SMPS's inthe actual headphone earshell, with some analogue circuitry, it is silent.
 
As an example, I can hear TV flybacks and most flash units.
By the way, the two earliest and most used SMPS over the whole Earth surface.
Not the best examples, as you've said the earliest. TV's not that many CRTs these days, and you wouldn't use the PSU out of a flash for audio.
Done correctly SMPS's are quiet in the real world and are in numerous products, but I forget they are the devils design:rolleyes:
Oh my new flashguns are silent, no whine when they are re-charging! Must be broken:D
 

kouiky

Member
2009-06-18 4:42 pm
This might not be quite the answer you were looking for, but yes I can hear a switching power supply from some distance. What I hear are the subharmonics in the 15-20kHz range coming from the physical power supply itself. Internet routers, iPod usb chargers, certain TV sets and DVD players are the worst offenders, with routers being so bad I have to close them in another room. I had a Power over ethernet system in 2011 and it was painful.
 

kouiky

Member
2009-06-18 4:42 pm
I don't have tinitus, my hearing threshold is 0dB from 4-8kHz which was regarded as very sensitive. The switch mode psu in my router is loud enough to record at a distance and has to be in a room away from me. Thats a good idea, I should record these things.
 
:) That is sensetive, one of my sons hearing is quite bad, and in that region, his is 20-60dB down in that region, so over the years I've learnt a lot about speach (he had speach therapy for over 10 years). Do voices sound over sibliant.
What worries me is that noisy SPMS's are generaly badly designed and EMC transmitters, and routers are one of the most competetive markets, so I know it is one area where cost cutting is rife.
Communications over power wont help, it is basicly EMC pollution and being on the mains can get into all sorts of equipement.
The reason why i mentioned tinitus, is that I suffer from it and when it kicks in certain frequecies seem that extreme they hurt, luckily I seem to have it under control most of the time.
What make is your router.
New multiphase spread spectrum SMPS's are much better than the older style single transformer or inductor versions, but again it comes down to cost, though as you can use smaller SMD magnetics the cost difference is not as bad as it might be. But they are only now filtering down in to consumer and commercial designs, but they are critical in their layout and effectivly you have x number of controllers plus discrete components, then the spread spectrum controller and the muliphase clock generator, good fun to do.
 
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