Audio amp with switch-mode PS

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batdin

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I intend to make a high-quality audio power amplifier with a switch-mode power supply (half-bridge at 110kHz).
I am sure there will be a big problem with interference due to the switching noise.
I want to know if anyone has dealt with such problems and what techniques he or she used.
Thank you in advance!
 

Hi! I use with my 2 channels tda7294 amplifier smps based on ir2153 (fluo lamps driver from IR) + pair irf740a at ~ 70 kHz without any troubles. It works great for me, when computer is off (my music source) i can't hear any noise and it's difficult to understand is amplifier on or off. After the secondary rectifiers i have yellow core toroid inductors from died pc smps and 2200 uF caps.
Good luck
PS. Sorry for bad English
 

You can use Common mode and differance mode filters to reduce noise at the output and additionally use proper snubber accross the main switching device and the output rectifier
 

Yes,I think I did this properly.
The problem is that the output ground seems to contain a lot of HF switching noise.When I connect a 1nF capacitor from output ground to AC mains the noise is reduced but not eliminated.
If I connect it to AC mains ground directly,this should be solved but I am afraid that not all AC plugs have separate ground.(At least in my country).
And this noise acts as an input signal to the amplifier if a sound source is applied.
 

Hello

You can use the big yellow torroid choke coils found in PC power supplies, and really big capacitor, say 4700 µF, or 10000 µF.

Regards
 

hi,

i've made a smps with IR2153+IRF740 too, but i have minor problems with core saturation (f=60khz, core from pc power supply)...

anybody willing to share experience?
 

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