That not the case with a class D amp. The frequency(s) and amplitude will be power dependent.
The lower the power the relatively higher the level of the switching noise/tones.
So you can not say anything about the HF output voltages based on that graph, we need to know what 0dB was.
I am concerned about RF pollution. That’s why I didn’t plunge to class D yet.
However, there is a question of how much of that RF flowing through cabling and load is actually radiated. Loudspeaker cables doesn’t make an attuned antenna.
One of those in favor of class D measured, during normal listening levels, that radiated RF measured 1 m away of the Purifi amplifier is considerably below signal of actual AM stations. About -100 dBm.
https://audiosciencereview.com/foru...ss-d-amplifiers-measurements.9940/post-273296
He s using a 2m cable, let him use a 4m one and see the result.
Also he s using powefull broadcsast emitters as convenient comparison, because -63dBm amount to 500uV signal from his antenna and the second emitter at -75dBm is at 100uV.
Beside given the wave length 1m distance is not enough as the antenna is within Fresnel area where its actually radiated power cant be measured the way he does, someone at 200m distance would measure way higher amplitude, for the same reason the broadcasting emitters signals are accurate because they are distant enough.
That s a typical case of someone using involuntarly ignorance to prove a point.
Also he s using powefull broadcsast emitters as convenient comparison, because -63dBm amount to 500uV signal from his antenna and the second emitter at -75dBm is at 100uV.
Beside given the wave length 1m distance is not enough as the antenna is within Fresnel area where its actually radiated power cant be measured the way he does, someone at 200m distance would measure way higher amplitude, for the same reason the broadcasting emitters signals are accurate because they are distant enough.
That s a typical case of someone using involuntarly ignorance to prove a point.
This is nonsense, I have been listening to class D high power and never had any issues with what you describe.
There are millions of class D amps in use around the world with zero, none, nada complaints.
They all comply with EMI rules of your 'authorities'.
I understand what you are saying but your armchair ramblings have nothing to do with reality.
Jan
Jan, reality is to know what is a EM wave and that a 700m wavelength amplitude cant be measured at a 1m distance,
the guy who stated levels at 1m distance is just cluless.
So much for armachair rambling, when one has to resort to ad personae it means that he has no argument a all,
just use an AM radio with LW/MW/SW as detector and you ll see by yourself, i m 100% sure that you never made
such a basic test, and one more time so much about talking reality without even checking the thing, so far i ve
never seen a high frequency switching device that do not create perturbations within those radio frequencies.
the guy who stated levels at 1m distance is just cluless.
So much for armachair rambling, when one has to resort to ad personae it means that he has no argument a all,
just use an AM radio with LW/MW/SW as detector and you ll see by yourself, i m 100% sure that you never made
such a basic test, and one more time so much about talking reality without even checking the thing, so far i ve
never seen a high frequency switching device that do not create perturbations within those radio frequencies.
They are supposed to pass EMI limits to be certified CE but there are no strict controls as the certification
is done by the manufacturer of the product and no more by states independant organisms like decades ago,
that s why there s currently tons of non conform items sold on the market and nothing will happen as long
as there s no complaints.
A CE non conform item can still be legally sold but it has to be stated as evaluation product, exactly what Purifi
are labelling their kits, as evaluation kits, this way the CE sticker and EMI limits are not mandatory.
https://www.audiophonics.fr/fr/287_purifi
Edit : Try a AM radio test while you have those amps at hands.
is done by the manufacturer of the product and no more by states independant organisms like decades ago,
that s why there s currently tons of non conform items sold on the market and nothing will happen as long
as there s no complaints.
A CE non conform item can still be legally sold but it has to be stated as evaluation product, exactly what Purifi
are labelling their kits, as evaluation kits, this way the CE sticker and EMI limits are not mandatory.
https://www.audiophonics.fr/fr/287_purifi
Edit : Try a AM radio test while you have those amps at hands.
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Why do you keep coming up with such BS?
In some cases you can do self-certification, but that has to be complemented by calibrated measurements. I know, I've done self-certification for beauty equipment. It's very involved and you can't cut corners. Regulators are not stupid.
The companies I know that produce class D and SMPS and other switching equipment (streamers anyone?) pay a lot of money to official recognized certified bodies to do the certification process for them.
First you say: 'That is because regulation authorities are not aware of the huge EM pollution'. That's completely wrong.
Now you say: 'there are no strict controls as the certification is done by the manufacturer of the product and no more by states independant organisms'
which is also incorrect.
And do you really believe that all those hundreds of thousands of units that have been sold or integrated in hi-end amps or active speakers are all labelled 'evaluation units' so they can spread EMI all over the place?
Really? Maybe you should stop digging yourself in.
Jan
In some cases you can do self-certification, but that has to be complemented by calibrated measurements. I know, I've done self-certification for beauty equipment. It's very involved and you can't cut corners. Regulators are not stupid.
The companies I know that produce class D and SMPS and other switching equipment (streamers anyone?) pay a lot of money to official recognized certified bodies to do the certification process for them.
First you say: 'That is because regulation authorities are not aware of the huge EM pollution'. That's completely wrong.
Now you say: 'there are no strict controls as the certification is done by the manufacturer of the product and no more by states independant organisms'
which is also incorrect.
And do you really believe that all those hundreds of thousands of units that have been sold or integrated in hi-end amps or active speakers are all labelled 'evaluation units' so they can spread EMI all over the place?
Really? Maybe you should stop digging yourself in.
Jan
NAD C298, which is Purifi, does have the CE certification mark (see the photo on NAD Electronics' web site).
Frankly, I don't think all that EMI talk is to the point. Yes, Class D does have EMI issues to manage that Class AB doesn't. Bruno Putzeys, in particular, has been dead serious about it from early on - see, for example, his 2007 AES masterclass. He claims his products has met or surpassed regulation requirements, and very likely, he knows what he's talking about (while many reviewers so obviously don't). If there will be different requirements, Class D designers will meet them, too. On the other hand, AM radio has never been intended for high quality and nowadays seems to be relegated to auxiliary roles such as highway advisory (remember those "Urgent message if flashing" road signs?). EMI is part of it, but Class D if far from being the biggest problem - SMPSes and Ethernet-over-powerline adapters are. Even in Class D, Purifi is not the biggest offender - it is the myriad Class D chips of various quality that power the speakers of your TV and what not. Class D is the new tech, AM is the old and outgoing one.
But I digress🙂
Frankly, I don't think all that EMI talk is to the point. Yes, Class D does have EMI issues to manage that Class AB doesn't. Bruno Putzeys, in particular, has been dead serious about it from early on - see, for example, his 2007 AES masterclass. He claims his products has met or surpassed regulation requirements, and very likely, he knows what he's talking about (while many reviewers so obviously don't). If there will be different requirements, Class D designers will meet them, too. On the other hand, AM radio has never been intended for high quality and nowadays seems to be relegated to auxiliary roles such as highway advisory (remember those "Urgent message if flashing" road signs?). EMI is part of it, but Class D if far from being the biggest problem - SMPSes and Ethernet-over-powerline adapters are. Even in Class D, Purifi is not the biggest offender - it is the myriad Class D chips of various quality that power the speakers of your TV and what not. Class D is the new tech, AM is the old and outgoing one.
But I digress🙂
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Do a test with an AM receiver, this will be more telling than any discourse and tell us the results, because here you are
talking without even checking the facts while i m talking of real experience.
@alexcp
Stating that class D is the new tech and AM is the old and outgoing one is everything but an argument, it s like
saying that it could be right but that it s of no importance.
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I have a old Sony am/fm alarm clock 1989 , fixed from the junk. My 10A/ 5V SMPS totally makes whistles and noises next to it.
In fact ,the sound changes if I load it down with lots of ESP-32 controlled LED's.
My hypex uCD , I can put the radio right on the amp - no noise. the Hypex self oscillates @ >400Khz , but is designed (good)
I can hear the slightest noise , but have to put the AM wire right on the switchers.
Newer and well designed SMPS or class D present minimal interference. Some , but VERY minimal.
A cheap China Ebay SMPS , I would expect less than ideal !
Edit - forgot to mention the typical phone charger SMPS - horrible !
OS
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Very true. I am a DX-listener, and you can here them complain about, especially, SMPS causing interference in the amateure radio bands. Do a Google search and you will find plenty info, for instance: interference on radio bands @jan.didden what in audio terms is considered noise and distortion (uV signals) IS the signal in radio terms. Not saying 'your piece of equipment' has issues, but for sh**s and giggles, don't you have one of these portable SONY world receivers lying around you could try next to your amplifier?
Flat screen monitors are also quite nasty.
I'm doing the AM pocket-reciever test all the time (in LW, MW and SW bands) to get a feeling how strong and where exactly a device radiates. Class-D amps are definitely not among the worst offenders.
But mind you, a receiver is designed to pick up extremely weak signals and therefore it must react to pretty much anything, even when it is many orders of magnitude below the limits of current EMC emission standards.
I have my linear on a separate power strip , my digital (with SMPS's -PC) connects optically. Cheap SMPS's can turn the whole power strip into a transmitter.
Yes , filter my linear strip (below). Power company Sine is still distorted by all the scamerica cheap China SMPS's through out the building.
Here in "scamerica" , SMPS china junk can infiltrate despite having "CE" and other loosely regulated safeguards , which are overlooked to make more profit.
I like EU , they actually adhere to rules. Internet is the same in "scamerica"....
OS
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I apologize for the long absence. I live in Kyiv, - we often have air raid sirens. And after the bombings, there is often no electricity and internet_access for a long time. But you can still find the basic information on my Patreon http://patreon.com/nick_sukhov
No problem Nick (thx for this Information, it's sad),
the situation in which the globe finds itself and the life forms directly affected, as well as the people with their families, is terrible - I simply don't have the right words, it's stupid / unreasonable madness. But let's leave this topic and look for the beauty instead.
#
My problem with our hobbyhorse is:
I don't have access to Patreon and don't want to set one up. We are here in a DIY forum that is open in all directions; the approach we are pursuing is the “free, transparent exchange of knowledge and ideas”. We exchange views and share information completely openly. With this in mind, I would also like to see a PDF document attached to your interesting projects, preferably in English. This is the only way to archive and preserve your extensive knowledge and experience here.
If you like, I can open a new thread that deals specifically with your ABBA concept.
Kind regards,
HBt.
Psst
I've given (all of us) each of the last posts a “like” because your /our arguments are just so delicious.
EM regulations define limits of allowed emissions - thus there remains a level of allowed disturbances.
Thus finding some noise on your AM radio under totally unknown circumstances does not prove anything.
Thus finding some noise on your AM radio under totally unknown circumstances does not prove anything.