A subwoofer plate amp that I have the schematic for is like this.
1. Draw an OP amp.
2. The signal is connected to the - input through a 1K resistor. Also connected to the - input is feedback from the output through a 910 ohm resistor.
3. The signal is also connected to the + input, through a 1K resistor and a 0.022uf capacitor. Also connected to the + input is a 1 meg pot and an inductor (unknown value) in series and going to ground. Phase is adjusted using the Pot.
Go figure.
1. Draw an OP amp.
2. The signal is connected to the - input through a 1K resistor. Also connected to the - input is feedback from the output through a 910 ohm resistor.
3. The signal is also connected to the + input, through a 1K resistor and a 0.022uf capacitor. Also connected to the + input is a 1 meg pot and an inductor (unknown value) in series and going to ground. Phase is adjusted using the Pot.
Go figure.