This is first post, I built a dual mono LM3886 with two 300VA transformer and 10000uf/63v cap per rail, the sould is pretty good overall, but everytime when someone mechanical turn on or turn off the light power and sometimes the Refrigerator Compressor also influence , my speaker will have "pia" noise, but this situation not happened for my previous power amp, except this the background is very silence, is anyone experience for this , thanks.
The noise may also be coming from your ground. I'm assuming your amp has a safety ground going to the wall outlet. Your refrigerator may be injecting noise into your building's ground wiring, which is finding its way into your amp. Fortunately, there is a rather nice article on this web site which deals with this problem. Here is the link:
http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html
Chapter 2 deals, specifically with the problem of noise.
Good luck!
http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html
Chapter 2 deals, specifically with the problem of noise.
Good luck!
Don't regulate.
Attenuate the interference.
Fit an RF filter at the input of the chipamp.
Consider adding a filter direct across the RCA input sockets.
Fit mains filter. They are available ready built as IEC sockets with all the correct components inside. Obtain the lowest current rating that will safely power your equipment. They are usually available in 1A, or 3A, or 6A
A metal chassis completely enclosing your amplifier also attenuates interference, especially if you have unattenuated emissions coming from radios and motors around the house.
It is always better to attenuate interference at source. Move the mobile radio, the wireless alarm system, the wireless doorbell, the wireless computer network, etc.
Fit all motors especially and switches in general with a snubbing network. These too are available ready assembled.
Attenuate the interference.
Fit an RF filter at the input of the chipamp.
Consider adding a filter direct across the RCA input sockets.
Fit mains filter. They are available ready built as IEC sockets with all the correct components inside. Obtain the lowest current rating that will safely power your equipment. They are usually available in 1A, or 3A, or 6A
A metal chassis completely enclosing your amplifier also attenuates interference, especially if you have unattenuated emissions coming from radios and motors around the house.
It is always better to attenuate interference at source. Move the mobile radio, the wireless alarm system, the wireless doorbell, the wireless computer network, etc.
Fit all motors especially and switches in general with a snubbing network. These too are available ready assembled.
The cap across pins 9, 10 should be 150-220 pF. The values you suggest would impair audio performance.
Also note that to maintain a clean transient/step response, you should add the RC in the feedback path shown in the data sheet (AC Test Circuit #2, if I recall correctly).
A better way to address OP's issue with clicks and pops would be to use an RF filter on the input of the amp. I generally add a few RCs on the input to knock anything above 0.5-1 MHz down considerably. Given the age of this thread, I suspect OP has moved on, though...
Tom
Also note that to maintain a clean transient/step response, you should add the RC in the feedback path shown in the data sheet (AC Test Circuit #2, if I recall correctly).
A better way to address OP's issue with clicks and pops would be to use an RF filter on the input of the amp. I generally add a few RCs on the input to knock anything above 0.5-1 MHz down considerably. Given the age of this thread, I suspect OP has moved on, though...
Tom
Last edited:
Interference can be radiated and/or conducted.
If its radio interference then the amp needs a low pass filter on the input.
If its conducted down the mains then a filter on the power supply will be required.
I have got caught out with lack of power supply spike filtering before.
I unplugged my soldering iron and the spike got into my amp and blew the output transistors. I now always add local 100nf and 100uf capacitors to the amplifier pcb.
If its radio interference then the amp needs a low pass filter on the input.
If its conducted down the mains then a filter on the power supply will be required.
I have got caught out with lack of power supply spike filtering before.
I unplugged my soldering iron and the spike got into my amp and blew the output transistors. I now always add local 100nf and 100uf capacitors to the amplifier pcb.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.