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This is an odd request for a circuit. I want to drive multiple speakers mono not differential from the same microcontroller. I want to just drive a tone through 8 8-ohm speakers so I thought I could just use a single oscillator circuit. I want to use the microcontroller to switch / enable them to oscillate and then I can modulate the enable.

Since I don't intend to drive more than 3 at a time, and they can take a maximum of 0.4 W each, could I use a single 3W Class D op amp?

Sorry I made a crappy image before I realized there is a schematic app but in essence could I construct a circuit like this that works?

rough sketch schematic where [in] is the oscillator input and after the op amp the 8 ohm speakers are enabled by a MOSFET switch low side. The multiple [Vin] are from the microcontroller are switched GPIO.

I know speakers are represented by resistance but they are coil magnets in reality. Is there anything I am missing that would defeat this circuit?

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In principle this should work. But if you drive 3 x 8-Ohm speakers at one time you have a load impedance of 2.6 ohm which may be too low for an LM386, you will need to check the datasheet to find out. You could use 32 Ohm speakers which is a load of 10.6 Ohm.

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