What can I do to minimize electromagnetic radiation from power amplifiers?

[orangejello]

Should we tell him about neutrinos?

I kind of get it. I used to fret about one amp that I had - an 845 based SET that was biased at a very high 1000 V if I recall correctly. It had a separate and massive power supply which utilized, among other tubes, two 866A half wave mercury vapor rectifiers. They glowed a most lovely blue-purple - a very nice light show along with the 845s in the evening with the rest of the lights turned out. Apparently at high enough voltages the 866A emitted xrays. I once took a course in radio isotope theory and remember measuring the stopping power for various isotope radiation. Wound up putting the amp in a glass rack case to ease my concerns and calling it good. Probably silly, but oh well... the mind does interesting things when you obsess about something and don't know enough to talk yourself out of it.

 

[raindance]

In my experience, most houses don’t have navigation or combat systems, ymmv of course.

I was responding to a post that asked

No, I am correct. The Hypex and Purifi PSUs and modules are CE approved. So are ICE etc. Whilst of course its not impossible for a manufacturer to completely screw things up, the fundamental components are fine and tested. You are extrapolating and generalising. I have no doubt some badly designed and untested SMPS ar class D amp could cause problems, but this is true of any product.

BTW I used to represent Keysight products and used to sell RF spectrum analysers for looking at precisely this sort of thing (yes I know what a LISN is )

The unit I measured was made by Class D Audio in the USA and contaminated every circuit in connected equipment.

 

[Panelhead]

Is that the Cherry line of amps?

 

[Panelhead]

My mistake, the Cherry are from Digital Amplifier Company.

 

[Tatteredmidnight]

I was responding to a post that asked

Sorry if that came across poorly, it was intended as a joke.

 

[restorer-john]

I simply wonder if there is not a lot of dirt added in the power line delivering no more simply just 50Hz anymore.

Would that influence our Hifi ?

Absolutely it does detrimentally influence your HiFi.

Ripple control used by the electrical companies to grid-control load switching for peak and off-peak devices (like electric hot water systems) is very audible. Luckily, it only lasts for a minute or so and manifests as patterns of mid frequency tones, like bursts of fast morse code. If you happen to be in the middle of testing or using a sensitive piece of test gear, you'll get some wild results.

Ripple control signal (internet pic)

 

[Harmonie]

Absolutely it does detrimentally influence your HiFi.

Ripple control used by the electrical companies to grid-control load switching for peak and off-peak devices (like electric hot water systems) is very audible. Luckily, it only lasts for a minute or so and manifests as patterns of mid frequency tones, like bursts of fast morse code. If you happen to be in the middle of testing or using a sensitive piece of test gear, you'll get some wild results.

Ripple control signal (internet pic)
View attachment 84523

AhhhaaaA !
Thank you

 

[raindance]

Sorry if that came across poorly, it was intended as a joke.

Yes, I figured this out and tried removing the comment before I posted, but the change didn't take!

 

[Colonel7]

Should we tell him about neutrinos?

Yes! Let's get some megascience neutrino experiments

 

[Nebbermind]

Instead of guessing and worrying over some random thoughts, why not invest in some sort of spectrum analyzer and measure what is bothering you?

 

[MakeMineVinyl]

When I was a recording engineer at a large recording studio, there was a military contractor just a couple blocks away who tested radar which would emit periodic RFI/EMI blips and beeps onto the master tape machine and console which would of course get recorded. There was nothing they could do and just had to suck it in and hope that it didn't wreck the perfect musical take which could never be repeated.

 

[Nebbermind]

There must be a lot of invisible signals out there, esp if you live near some transmission towers, substations, 3/4/5G repeaters.
If the interference is beyond the audible band, then you can filter it out. If within, nothing much you can do... Well, maybe living in isolation deep in the forest

 

[MakeMineVinyl]

There must be a lot of invisible signals out there, esp if you live near some transmission towers, substations, 3/4/5G repeaters.
If the interference is beyond the audible band, then you can filter it out. If within, nothing much you can do... Well, maybe living in isolation deep in the forest

I don't think there is much interference in the audio band aside from the VLF transmissions the government uses to communicate with submarines at sea and nuclear missile silos. If there's much activity on that band, the end is near and none of this matters, unfortunately.......

 

[solderdude]

Actually, VLF waves have such huge wavelengths they won't induce much current in wires of just 1 meter.
In case of MM cartridges and the right capacitive load you may pick up a radio station or so but not much more.

Interference from HF is more likely, you just need a few cm. This can induce voltages high enough to be rectified (as in AM detector) by one of the transistor PN crossings in a SS amp. (like the radar signals)
I guess most people that have had their phone very nearby a sensitive device and someone called that phone may have heard the familiar 'sound' coming out of their speakers before the phone even rang.
This is because the phone puts out max RF in order to attempt to establish how much RF power it needs to use to make a good connection.

 

[tomtoo]

More seriously and not related:

Do you folks in US have smart (electrical) grid ?
In France they impose you little by little communicating electrical counters.
These use Ghz waves to monitor your consumption in your home so many debates about freedom, health harmful aso.
I simply wonder if there is not a lot of dirt added in the power line delivering no more simply just 50Hz anymore.

Would that influence our Hifi ?

It never did. A lot of signals go over the powerline since many tenth of years. One example is switching on and of street lamps.

Edit says:Oh John already told. In german its called Rundsteuertechnik.

 

[tomtoo]

I see,

So we have clean power ? Even better than DC from batteries ?

Oh you can get DC from the powerline. But 800kv maybe a little to much for the home amp.
https://en.m.wikipedia.org/wiki/High-voltage_direct_current

 

[mansr]

This is what one cycle of mains voltage looks like at my desk at the moment:

Spectrum up to 1 kHz:

Spectrum up to 500 kHz:

My RF spectrum analyser would probably explode if connected directly to the mains, so I'm not going to do that.

 

[solderdude]

There seems to be plenty of time to top off those smoothing/reservoir caps behind the rectifier !

 

[Deleted member 9685]

With Gigahertz Solutions ME3851A, you can measure electric field portion of electromagnetic radiation between 5hz and 100khz.
The resolution of ME3851A is 0.1V/m which is good enough.

This is good for measuring electromagnetic radiation in near field.

Spectrum analyzers also measure electric field and magnetic field instead of electromagnetic radiation because it's impossible to measure electromagnetic radiation from nearby devices in low frequency ranges. Spectrum analyzers are expensive, by the way. If I had more money, I would buy one to measure electric field.

Electromagnetic radiation measurements become reliable beyond 2 or 3 wavelengths. The wavelength of 100khz is 3 kilometers. It's better to just measure electric field below 100khz or use Tecsun PL-600 to hear electric field above 100khz.

Whether I want to buy ME3851A or a spectrum analyzer, I need more money. I am going to make more money. I'm going to focus on making more money. That's my focus for now.

 

[solderdude]

Measuring V/m is fine if you want to know if limits are reached.
It won't say anything about how much influence there is.
A device can be very sensitive for say 30MHz but totally insensitive for 33MHz.
Using another cable can change things substantially.

Using a radio only says something about the presence of a field and says little if nothing about actual levels, modulation depth etc.

Fun for those who want to show there are fields in the Ether but not of any practical usage for determining if equipment will be influenced.

On top of that meters such as these are inaccurate and merely give an indication. One would need to measure in the proper conditions (EMC lab) to get accurate readings with far more expensive equipment.