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Old 5th October 2010, 09:47 AM   #1
diyAudio Member
Join Date: Oct 2010
Default Strange RFI/EMI problem with self-made amplifier

I have built my first stereo chip amp using a Sanyo LA4227 IC for two 3W speakers.
The speakers sound well, but whenever somebody turns on/off any switch in my house (even in other room), annoying popping sound occurs in both of them, which increases with volume. What could be possibly be the reason? Poor grounding/shielding? Any help will be much appreciated.

P.S. I did not have access to a PCB so I made the circuit only by soldering the points with short copper wires.
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Old 5th October 2010, 11:23 AM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
add an RF filter to the input of your amplifier.

What feeds your amplifier? It too may need an RF filter.
The speaker lead terminals also need an RF filter.

Particularly troublesome interference equipment will need suppressing at source. These are anything with a motor inside.

Post a schematic and a pic. There may be an instability in your amplifier that is responding to fast transients and exaggerating what comes out to the speaker.
regards Andrew T.
Sent from my desktop computer using a keyboard
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Old 5th October 2010, 11:36 AM   #3
marce is offline marce  United Kingdom
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Join Date: Jun 2007
Location: Blackburn, Lancs
Your PSu circuit would help, as this is your first line of defence from mains noise.
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Old 5th October 2010, 11:41 AM   #4
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Join Date: Jul 2005
I vote for the schematic too - sounds like impulse noise, which will usually be knocked out by an LC filter
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