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.
Additionally, in a past life, I designed switching power supplies for submarines and had to implement a method for passing EMI/EMC tests, so I'm familiar with methods to quell switching noise, just not sure whether it matters at all in this scenario.
Well...bet you weren't expecting that!Easily measurable with a scope on signal lines and chassis of all connected gear. I've seen tens to hundreds of millivolts. I don't know if it's detrimental to performance of any gear, if it's at, say 400KHz, most audio gear isn't going to try to amplify that.
You again.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?
No they don't.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.
It's a possibility although unlikely. However any amp, class d or or not should have appropriate input filtering. There is a thread here where someone reported noises with their class d amp (not one of ours). At my suggestion implemented an input filter and problem went away.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.
Wow, rampant electromagnetic radiation.....where does this stuff come from?
Don't forget incandescent light bulbs!The sun for example
Plenty common in the vacuum tube amplifier domain ('specially DIYers' efforts).Wonder why not LC or LCLC topology is more common ?
No they don't.
They have to pass both conducted and radiated emissions tests.
Secondly noisy mains is a given. Any product should be designed to cope with it.
Measurements are filtered to prevent issues with the range switching etc of the AP so that accurate results are obtained.
I can venture a guess or two why, but I am curious to hear from you since you worked on it. What is the problem with EMI/EMC in that situation? I'm especially curious about EMI, and also it pertains to this thread.
In my experience, most houses don’t have navigation or combat systems, ymmv of course.In that situation, EMI and EMC can interfere with navigation, communications and combat systems. Not very desirable with life safety on the line.
HUH?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.
Sorry, you're wrong. Many of these amps are kits and don't have to pass anything. And I'm not making this stuff up!