----------------POWER_AMP_TRICKS-------------------- _________/\ /\_ GROUND SEE IR | \/ | _/\ /\_____|______|\ | | \/ |-\ | _|_ | \______|__ /| / \ | / _|_/ | \___/ __|+/ | | | _|_ | |/ Amps |___| | /// _|_ | | \ | <-may see mV-> /// V _|_ \| \\\ A good way to make an oscillator is to assume ground is solid ground when using a power amplifier. Yes, Amps of output current can generate enough voltage on ground to feedback on itself. There are two tricks to handle this problem. _________/\ /\_ | \/ | _/\ /\_____|______|\ | | \/ |-\ | _|_ | \______|__ /| / \ | / _|_/ | \___/ __|+/ | | | | | |/ |___| | |________________|_______________| \ | signal ground _|_ \| up stream \\\ Power Gnd @supply One method is to think of how a city by a river handles its water. It usually gets its water upstream and dumps is waste water down stream. Think of current in a speaker as waste water. Ideally, this waste is dumped closest to the Ocean. This is the same as connecting the speaker closest to the power supply. The ground for the signal path should come upstream. That way, the output IR drop cannot make its way upstream to the input ports. In other words, you can't have a "ground loop". _____/\ /\_ | \/ | _/\ /\___/\ /\_|__|\ | | \/ | \/ |-\ | _|_ | | \______|__ /| / \ | | / _|_/ | \___/ |_/\ /\____|+/ | | | _|_ \/ | |/ Amps |___| | /// _|_ | | \ | /// V _|_ \| \\\ Another trick is to attentuate the right at the input of the power amplifier. The take some extra gain in the power amplifier. This will create a "local" ground for the power Amp. Any ground loop IR will be divided down by the attentuation.