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.
Total Comments 5
Comments
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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
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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
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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 analoguePosted 26th August 2016 at 01:41 PM by Stage Sound
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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
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Have the same problem, interfered with FM to the point I removed the amps from my systemPosted 20th October 2016 at 12:07 AM by scholl
