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

[Deleted member 9685]

For example, a class AB amplifier with a linear power supply such as Dayton APA150 doesn't have electromagnetic radiation associated with class D PWM frequencies and SMPS noise.

SMPS noise in house wires contribute to electromagnetic radiation from house wires. Good switch mode power supplies have common mode choke and a few other dirty electricity suppression tricks. But, I don't know which switch mode power supplies do their best to not pollute house wires. I will have to measure.

Other than SMPS noise and electromagnetic radiation at class D chipset PWM frequencies, I suspect there could be electromagnetic radiation around audio frequencies because power amplifiers have to deliver audio signals to speakers. Speaker cables can be shielded. I don't yet know what it would take to suppress electromagnetic radiation at audio frequencies.

Do you know good ways to minimize electromagnetic radiation from power amplifiers?

 

[Trouble Maker]

 

[RayDunzl]

Do you know good ways to minimize electromagnetic radiation from power amplifiers?

Do you have a measurable problem where, if you try something, you can objectively observe the result?

 

[Mnyb]

You don't need to anything with perfectly good products from reputable brands , they all fullfill the necessary regulations .

Weird voodoo high end or DIY may not always apply for "normal" function .

Screening of speakers wires are generally not done due to high current low impendance interface , to induce any significant voltage you have to use a heck of magnetic field . Exception wierd high end instable amps ? otherwise i think the field have to reach credit card erasing strengths ? is there any brave soul that owns a tapehead demag unit ? lets try don't send the bill to me if the amps blow ...

 

[kn0ppers]

A Class AB output stage will draw half wave rectified, nonlinear currents from the supply rails. The resulting magnetic fields can induce distortions into the input circuitry of the amplifier.

 

[Wombat]

Enclose the amplifier in a Faraday cage.

Better still, get an amp that doesn't present a problem - probably 99.99 plus percent of them.

 

[raindance]

Class D amplifiers do push a ton of switching noise back into the mains and back into all components connected to them. They also radiate switching noise from all their cables. Whether this is harmful or not, is something I've been wondering about. Not about human health, but about the added issues all this noise causes for interconnected components and whether it compromises performance. All the nice measurements you see are low pass filtered so the measuring equipment doesn't see the noise.

 

[Deleted member 9685]

Do you have a measurable problem where, if you try something, you can objectively observe the result?

Tecsun PL-600 translates electromagnetic radiation between 100khz and 30mhz into audio. PL-600 is pretty good. But, ideally, I want to measure down to audio frequencies(60hz ~ 20khz).
Esmog Spion translates lower frequencies than 100khz into audio.
If I really wanted to get the feeling of electromagnetic radiation in lower frequencies, I may try Esmog Spion (5G).

I can also measure electric field or magentic field component of low frequency electromagnetic radiation with expensive equipments, but they are expensive.

 

[Mnyb]

Well the so called linear powersupply is not always as good as one migth think.

For some reason it's only C capacitance after the rectifier ? add some overdimesiong off the supply and it's draws current from the mains in very short spikes , it migth be somewhat dampened by the inductance of the transformer . And powerfactor is not very good .
Add very fast diodes in the bridge and these too can produce noise in all bands

Wonder why not LC or LCLC topology is more common ?

Many switchmode supplies draws something similar to sinusoidal current (albeit with sqiugles that are the remains of the switching frequncy, but filtered ) and are powerfactor compensated , so the current you use is actually active current going to produce amplifier power and not just driving some reactive current to the mains , that gives losses in the wires and possible overloads the fuses like a not so well designa linear supply would do ?
With the rigth filters SMSP probably polutes less than some linear supplies

SMPS has advantages too , it's not always bad as audiophile mythology will have it .

It's as always about implementation . If it's bad it's bad does not matter what tech you use .

 

[Deleted member 9685]

It's as always about implementation . If it's bad it's bad does not matter what tech you use .

Can you then recommend specific low-EMF power amplifiers?

 

[EdW]

Class D amplifiers do push a ton of switching noise back into the mains and back into all components connected to them. They also radiate switching noise from all their cables. Whether this is harmful or not, is something I've been wondering about. Not about human health, but about the added issues all this noise causes for interconnected components and whether it compromises performance. All the nice measurements you see are low pass filtered so the measuring equipment doesn't see the noise.

One possible issue, I’ve wondered about, with class D is the possibility of intermod with a ’noisy’ DAC output, perhaps playing DSD for example; could this produce tones in the audio band? We know that the March Audio Purifi amplifiers have a low pass filter in the input circuit and this could be one reason why, apart from not demodulating any spurious RF.

 

[Mnyb]

Can you then recommend specific low-EMF power amplifiers?

No ,I just assume that for listening most of what we can buy is fine buy any amplifier from a known and respected brand ?

This forum obsess about audio quality mostly .

What is your objective , what are you trying to do ?

Do you have a labatory of some kind ? do you want less EMF for some other reason than audio quality , for example music in your sensitive lab environment ?

 

[Mnyb]

I'm not qualified for giving advice about real low EMF environments on thier requirements.

But i do work in heavy industries where this can be a problem , I would say the EMF and similar is a non issue in homes , at least compared to any industrial application .

I've been places where we could not use CRT monitors at work because the picture is modulated and colapses by the sourounding fields

 

[Mnyb]

OT got curious this must be the most boring CD ever produced ....

https://www.priggen.com/CD-ROM-with...emodulated-High-Frequency-Interfering-Signals

Seriusly, some folks are uneccessary scared about EMF and such , lets not delve in to such myths

 

[Panelhead]

The electric fields are just like radiation. The three factors to reduce exposure are:

1. Time
2. Distance
3. Shielding

How you apply these to audio is up to your imagination.

 

[Unclevanya]

Can power conditioning (even modest surge protectors with filtering) provide any noise reduction in this range? At least for devices on the power distribution side within the house.

EDIT: I assumed this was about audio noise leaking into wires causing interference or audible effects... Then I read this: https://www.audiosciencereview.com/...romagnetic-radiation-from-class-d-amps.13011/

I'm going to just assume this is another backdoor attempt to convince is that all the evidential data on cell phones etc is bogus and we are all going to die horribly... So I'll not be responding to the op anymore.

 

[RayDunzl]

Can you then recommend specific low-EMF power amplifiers?

Have you considered using battery power?

 

[raindance]

Have you considered using battery power?

How would that stop switching noise?

 

[RayDunzl]

How would that stop switching noise?

What switching?

You power the device with the DC voltages that the linear or switched power supplies inside it would have output before you removed/bypoassed them..

A little surgery would be required, nothing exotic.

 

[RayDunzl]

Oh, ok, Class D output switching.

Battery won't save you there.

Have fun worrying.