View Full Version : Help with high output offset
I just finished my amp3 and pass the power-up test mention in the assembly manual, measuring with or without speaker connected, i have got have 34mV on one channel and 234mV on the other, when playing music in low volume, i also got some clicking noise on the high offset channel. i did resolder the chip and recheck all the solder joints but the problem remain unchange. the amp was power by 12V unregulator supply,what should i need to do now to lower the output offset and get rid of the chicking noise?
You should not get more than about 100mV DC offset. If you do, there is a problem.
The clicking noise is a sure sign that you have a connection problem somewhere. If the outputs are shorted to ground, for example. You may have a DC leak at the input causing your high DC offset. That would cause overload contions and clicking, too.
If there is a current leak from the input pins to ground it will cause a wild swing in DC offset at the output. All resistors to ground should be on the uptream side of the DC blocking cap input cap.
Measure your DC un the chip side of the input caps. You should see 2.5V on each input. If not, there is your trouble.
Fixed. One of the 0.1uF was shorted to the input ground. The offset now is 0mV & 34mV.
Great! Glad you got it going. Nice low offset, too.[8D]
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