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Chinese class D amp modules.

Posted 25th August 2016 at 10:42 AM by Stage Sound

I have imported several class D modules from China and all but one have had RFI problems and seemed to me to unusable and probably illegal in a production item. Far to much RFI on the output and looking at the on board components they have only a single stage output filter comprising of a square grey ceramic choke and one or two mylar caps. Has anyone else found the same thing and is there a mod that is known to work? The modules are all very well made using good quality components but like behaving like a radio transmitter.
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Views 747 Comments 5
Total Comments 5


  1. Old Comment
    You might start a thread about this in the Class-D forum. That is likely to get more responses than a blog post...
    Posted 25th August 2016 at 04:50 PM by CharlieLaub CharlieLaub is offline
  2. Old Comment
    abraxalito's Avatar
    I use output transformers, this is primarily to improve the SQ but also has the desirable side-effect of reducing the EMI.
    Posted 26th August 2016 at 06:07 AM by abraxalito abraxalito is offline
  3. Old Comment
    An OPT is not practical in my ap. I want to keep the weight down and traffo's aren't cheap or compact at 500 wrms!
    Hopefully someone has managed to snuff out the RFI without killing the high end frequency response. My guess is that a dual choke 3rd order filter is a must have. There dozens of these Chinese modules and Alibaba. If you haven't already guessed it, my audio background is pure analogue
    Posted 26th August 2016 at 01:41 PM by Stage Sound Stage Sound is offline
  4. Old Comment
    abraxalito's Avatar
    If you're playing music (not continuous duty sinewaves) then a crest factor of at least 12dB seems reasonable, hence for a 500W amp a 50VA transformer will suffice. Agreed its still fairly heavy and bulky.
    Posted 27th August 2016 at 05:12 AM by abraxalito abraxalito is offline
  5. Old Comment
    Have the same problem, interfered with FM to the point I removed the amps from my system
    Posted 20th October 2016 at 12:07 AM by scholl scholl is offline

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