Looking for an external remedy to eliminate high frequency static noise that I believe is generated from Class D integrated amp (output stage?). I don’t want to give up on the attributes of Class D but the intermittent distraction is causing me buyers remorse. Open to suggestions (not purchasing Class A’s). TIA.
EMI generated from my Eigantakt Class D Amplifier
- Thread starter bornie
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Is the noise still there when you turn off youre mobil cellphone and other wireless stuff.
I'd experiment with something like this on the inside of the case, in areas you think might reward you. I've read of a number of people doing this sort of work on the PS Audio forum discussion of their Directstream DAC MKI, but the thread is soooooo long it might be hard to find info about the materials they used.
If you'd like to search: https://forum.psaudio.com/t/modding-the-directstream-dac-mki/2680
Edit: Here's a likely better link: https://forum.psaudio.com/t/emi-rfi-absorbers/5043
If you'd like to search: https://forum.psaudio.com/t/modding-the-directstream-dac-mki/2680
Edit: Here's a likely better link: https://forum.psaudio.com/t/emi-rfi-absorbers/5043
What is the mechanism where you see the high frequency noise?
Is it noise or static?
There is the resonant frequency that the class-D runs at, so it is something like 750 MHz (or whatever).
That is either sneaking out of the power line, or being emanated out out of the cables, or via the ether.
And then…
What is that coming into where the noise shows up?
I use a battery powered portable AM FM radio to help find EMF sources, tune it into No station (static) and wave it over the suspected object. Try both AM & FM bands, it helps if the radio has no self tuning chip, so an older or basic radio is actually better here.
Wave it over a cell phone charger, and hear if it sounds like a good idea to sleep right next to it. Most people don't care though.
Wave it over a cell phone charger, and hear if it sounds like a good idea to sleep right next to it. Most people don't care though.
The audible buzzing/static noise suddenly appears thru the tweeter & midrange on my Von Schweikert VR55’s. The bass drivers are managed thru internal Class D’s and are not affected. I’ve change Power & Speaker Cables and ran power thru a different wall outlet.
WOW, that’s interesting!!!
I honed in on your description of “intermittent“.
You may want to investigate whether an appliance in your home is running when the noise is present. Such as your furnace or refrigerator or power vent water heater, etc. basically, something with a motor.
You may want to investigate whether an appliance in your home is running when the noise is present. Such as your furnace or refrigerator or power vent water heater, etc. basically, something with a motor.
Thanks! Isolation might be the key… perhaps a thin layer of lead around the “box”… Today I’m going to try a power conditioner, just because, to see if it’s introduced on/in the AC line.
That is not likely to be a class-D amp problem.
Any “sudden” thing seems more like RF coming in through the RCAs or power… especially if it the zzzt-zzzt-zzzt of a cellphone handshaking with the tower.
The speaker cables are generally looking at a low impedance, but it is hard to say up at RF.
^this^
If it is really up in the tweeter range, then it is hard to imagine it might be a motor… but any inverter type of controller would certainly be able to get up to the tweeter range.
If it were “sudden” and always in the evening, then I would be looking for a HAM radio station nearby.
And/Or looking at using XLRs…
Republicoftexas69
Well-Known Member
I have also seen here on this forum that some folks will affix a small strip of this material on there IC and Power Cables to reduce RFI. As a bit of a tweaker I will get around to this even though I am not suffering any of these symptoms, that I am aware of. Some time implementing a fix will reveal having an issue you were oblivious to.
Awesome!!! I
Awesome!!! I have an electrician due in, in a week or so! An EMF meter might be in his tool bag!!! If not, I’ll purchase! Thank you!
This is a known also they are apps for phones for EMI
You can also you a scope ground to each device then use the probe
And wave it over devices .
now where the noise you hear is complex in itself . You can find noise but this doesn't mean it's effecting your system.
Do you have tubes anywhere ?
What makes you think it's EMI?
Class D amps can be extremely musical but they have a problem. Class D is not digital but they do induce a digital-like bi-directional noise much like or even identical to digital due to their high-speed switching modules. Bi-directional implying that the noise goes back up the AC line back into the wall and some say even as far back as the service panenl and then impacts other instruments.
That said, most likely what you are experiencing is this bi-directional digital-like noise at the int. amp's single AC inlet such that the noise is being shared there for both L&R channels.
But in your case, it's even worse than that with an integrated Class D amp. The pre-amp section must borrow power from one of the 2 channels so the pre-amp section is already bombarded with digital-like noise from the two channels.
But it's even worse than that. Now you have the two channels polluting pre-amp or line-stage and then those distortions are magnified by the gain-stage.
I've gone thru this myself years ago, ran a few experiments to confirm, etc. and to the best of my knowledge, there's not a darn thing you can do about this.
Again, Class D can be fabulous performers but there are several rules that must be followed:
1. Never buy stereo Class D amps unless each channel has its own dedicated AC inlet.
2. Never ever buy an integrated Class D amp because the linestage must borrow already distorted power from one of the channels.
That leaves only one reasonable / musical solution for Class D and that's Class D monoblock amps. Additionally, find yourself some superior passive, dedicated, and bi-directional filtering line conditioners for each of the monoblocks but also for all of your other gear too.
This is my current config as I employ Wyred-4-Sound Class D monoblock amps and compact Jena Labs The TWO passive, dedicated, and bi-directional filtering line conditions everywhere regardless of component or type. Problem is either absolutely minimized or solved.
When I decided to try Wyred-4-Sound back in 2014, I initially purchased their 575wpc Int. amp and what I experienced was insanely unmusical. I tried to reason thru what the problems could have been and just before my 30 day satisfaction guarantee expired, it dawned on me what the problem most likely was so I swapped out the int. amp for their 575wpc monoblocks and still have that same config to this day. Tremendously musical monoblocks in my book.
A good class D module is pretty low noise in terms of the 'bi-directional' noise to which you refer. Its often less noise than that generated by a tube amplifier.
Bruno Putzeys is the designer of the modules in question and I know he's very careful about radiated noise- he likes to be about 60dB below the required to pass the EU directives (to obtain the CE mark).
So unless something is wrong with a module, radiated noise isn't a thing with this amp.
Perhaps. Or perhaps not? To the best of my knowledge, the bi-directional noise generated is inherent to the high-speed switching module. Presumably, the heart of a Class D amp? If so, then it's up to the designer how best to sufficiently address the issue.
For some, sufficiently addressing the issue could be installing some cheap $5 AC filter just behind the AC inlet? And for some, that may be good enough - even though that $5 AC filter might induce addtional by-products/effects that compromise sonics in other ways - even IF it did sufficiently address the bi-directional noise.
Such remedies may not be much of a gamble for the designer, but it remains a potentially expensive gamble for the consumer. So for me anyway, monoblock amps are the only way for me to go when it comes to Class D.
Going with 'perhaps not'. The noise to which you refer is caused almost entirely by inductive parasitics. The more you keep lead lengths down and traces controlled in the module the less noise you have. This is why we used GaNFETs since they have no leads at all and its why all class D amps these days use surface mount.
Installing an AC filter won't do the job if you have a problem! But it can be helpful. In our amp, the lion's share of noise is the bridge rectifier (which you can find in tube and class AB amps) for the main power supply, which we have properly snubbed. But despite that it still makes a little bit of noise, which we put down another 60dB(!) by using an input line filter. Again, note that the bridge rectifier is far more noise than that of the module.
I can't speak for other class D designs. I once had a powered subwoofer using class D amp that made using the FM tuner a forlorn hope. It went back. IMO the CE mark on that sub was obtained by an ancient technique known as 'lying'.
Bruno Putzeys however is an excellent designer. I see it as highly unlikely one of his designs would have this problem. All bets are off if there's a malfunction. All bets are off with other manufacturers as well- each must be taken on a piece by piece basis.
It's not as amazing as you think , we can't hear what noise it finds . It's the modulation heard . So nothing
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