Do you need the electrical signal from just one end of a microphone’s voice coil, or do you need both in order to drive a speaker?

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Is there a positive and a negative end to the voice coil, or is that not a thing?

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Both, you need a circuit. Pretty much all electronics is designed in circuits, which means two wires (if something is grounded like in a car then the car’s chassis a wire). Sound waves entering a microphone are converted into electrical energy by a transducer. In most microphones there is a little transformer to step up the voltage before it leaves the microphone. When sound leaves the microphone it is still a pair of wires. I believe there is a hot and a ground/common. You must talk both these wires up to a speaker to drive it.

Positive, negative; it’s relative. It’s a simplified view of electronics. The core concept of any electronics is voltage, which is the *difference* in electrical potential between two things. You can’t have a difference between one thing. You need two things. Sometimes thing number 2 is ground, sometimes it’s a negative counterpart. But there does have to be two things.

You could make a microphone using ground as a reference, thereby defining the signal as its voltage relative to ground. This would be single ended. You’d still need two wires though, because it can’t be referenced to ground without somehow being connected to it.

Or you could define the signal as the voltage between the two wires of the voice coil, and leave ground out of it entirely. This would be a differential signal.

Both are entirely valid ways to solve the task, and in the end kind of the same. You need two wires to create a voltage difference.

Basically, if you not connect even one end of it, you not completing the circuit, you will not get any sound. 🔇