PSA: Short Unused Speakers and Subs in the Listening Room

Speakers move when input voltage applied to the coil creates a magnetic field that attracts it towards, or repels it away from, the fixed magnet. Moving the cone with your finger does the reverse, creating a voltage in the output. This is exactly the way a microphone works.

Shorting the terminals creates a situation where the same voltage being generated by moving the cone with your finger, is simultaneously putting voltage right back into the coil resisting this same motion. As a result it moves hardly at all.

If the speaker is sealed design then you have pretty much turned it into a closed box. But if it is ported then you have created a speaker sized Helmholtz resonator.

Shorting the terminals creates a situation where the same voltage being generated by moving the cone with your finger, is simultaneously putting voltage right back into the coil resisting this same motion. As a result it moves hardly at all.

Is that why it works? Makes sense. My assumption was that with an open circuit, only voltage is created and with a closed circuit, current can flow and the internal resistance of the wire and speaker eats up the power in the circuit. I hadn’t put too much thought into it. I think I like your explanation better.

If the speaker is sealed design then you have pretty much turned it into a closed box. But if it is ported then you have created a speaker sized Helmholtz resonator.

That would be a good thing right? Or is it only a good thing if your room has a nasty resonance peak at the absorbing frequency of the shorted and ported subwoofer?

By the way, I think the low frequency performance of my system increased after shorting the unused subwoofers. I was only able to listen to one song (that wasn’t especially bass heavy) after I made the change but it seemed clearer in the bass frequency department.

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