Strange RFI/EMI problem with self-made amplifier

res0nance · 5th October 2010, 09:47 AM

Hi,
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.

AndrewT · 5th October 2010, 11:23 AM

Hi,
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.

marce · 5th October 2010, 11:36 AM

Your PSu circuit would help, as this is your first line of defence from mains noise.

Psychobiker · 5th October 2010, 11:41 AM

I vote for the schematic too - sounds like impulse noise, which will usually be knocked out by an LC filter

5th October 2010, 09:47 AM	#1
res0nance diyAudio Member Join Date: Oct 2010	Strange RFI/EMI problem with self-made amplifier Hi, 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.

5th October 2010, 11:41 AM	#4
Psychobiker diyAudio Member Join Date: Jul 2005 Location: Montréal QC	I vote for the schematic too - sounds like impulse noise, which will usually be knocked out by an LC filter __________________ http://blog.liammartin.com

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5th October 2010, 11:23 AM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, 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.

5th October 2010, 11:36 AM	#3
marce diyAudio Member Join Date: Jun 2007 Location: Blackburn, Lancs	Your PSu circuit would help, as this is your first line of defence from mains noise.