Noise reduction -why the rage now ?


Is it better science ? Or more needed today with the ’surge’ of switching power supplies, smart phones and Wi-Fi routers ? Then, higher-frequencies in digital interfaces -now megahertz and gigahertz.

The problem with the "needed more today" theory is that one, listeners are hearing things they never heard before. One report is from Paul of PS Audio (on his blog) stating that a 4K power cord transformed his system. Yet he sells a Power Plant.

Two, many reports of lower noise (in the last 10 years) were in systems with linear power supplies, not switch-mode.

Three, for digital, many people were using AES/EBU or i-squared interfaces. These don’t have the noise concerns of USB.

Fourth, many people listen at night. They know better, due to the problems of a noisy day-grid.

Yet, there it is -large gains from the latest power conditioners, ground blocks and after-market power cords. To me, today’s science is much better at doing this. Along with the "need today".
jonnie22
williewonka
One might argue that the EMI/RFI generated by digital gear like phones is way above the human audible spectrum and some will debate their impact on sound quality - but I hear no evidence of sound quality degradation if I place digital devices close to components OR cables.

>>>>>This brings us back to the question: What is the signal? And why is it subject to RFI/EMI, which is not only above 🔝 the human audio spectrum, it’s not even in the same spectrum? 😀 (One is the acoustic spectrum, the other is the electromagnetic spectrum.)

One might also ask why seismic vibration interferes with the signal, too, even though it’s below ⬇️ the human audio spectrum; at least it’s in the same spectrum. 🤗 By inspection the signal in all the electronics and wire is not the audio waveform. ♒️ Hope this helps.
Microphony is different issue. RF can be "overcome" IF you use a very-advanced technique like the Nordost QPoint (just demo’ed at RMAF ’19).

But it’s still best to SHIELD parts from RF, rather than "overpower" it in the air...
I suspect you missed my points. My point is that RF is not in the audio bandwidth. And the audio signal is not the audio waveform.
geoffkait is right about RF. Radio Frequency (RF) is in the mega- and giga-hertz, way above sonic, and even ultra-sonic, both of which are in the kilo-hertz region.

That alone doesn't mean it can't create a problem we can hear. A common Boy Scout science project in the 60's was to build a crystal radio. Wire and crystal, you got a radio. Self-powered. String a wire from the garage across the yard into the upstairs window. Wrap the end around and around an empty roll of toilet paper. At the other end is a crystal. Forget what that was, I was a kid. But it was necessary. The wrapping is a crude coil rheostat.

Radio waves that are everywhere all the time cross the wire, inducting a tiny bit of current in the wire. A current that varies at radio frequency, too high to hear. Just exactly the same as FM (frequency modulated) or AM (Amplitude modulated) radio. Heck you can even look at an old analog radio, it says right on it MHz, so KZOK is 102.5 mega-hertz.

I forget if its the crystal or the rheostat, but either way its just static until you tune to a particular frequency. Anyone ever tuned an old analog radio should know about static. Then when you get it right, when your wire is tuned to a particular radio frequency, then out comes sound.

Which in the Boy Scout radio is barely enough energy to vibrate the toilet paper roll if you hold your ear real close. Which you can scoff with your modern high end rig but is pretty freaking cool when you are like ten.

Okay so anyway sorry for taking so long but as you can see they have so dumbed down education that stuff a kid used to learn in Boy Scout is now beyond the education of a theoretical physicist.

Because it should be pretty obvious by now, but its not, so I'll continue explaining. So now instead of one wire across the yard we're talking about lots of wires tangled around going everywhere from the coil in the cartridge to the phono lead to the ... well you get the idea. The wire goes into the phono stage where it gets amplified 45-65 dB which is a lot. And out comes.... static and.... some damn radio station! WTF!?!?

If you haven't had this problem goody for you. I sure have. A lot of people have. So it should be pretty obvious that RFI is a thing you can hear. With your ears.

Now a bit of a conceptual leap, same thing is happening in every wire everywhere all the time. And yeah you are not gonna hear it because you can't hear mega-hertz. Until and unless something comes along and tunes the radio frequency, which could be any damn thing. 

See? Its actually pretty easy to see how RFI can be audible. I mean, if a 10 year old Boy Scout can get it....
Yeah okay so I just asked a doc here and he made one as a kid. He's 10 years younger than me. So the intense dumbing down happened after that.