How to Power Two Speakers with a One Channel Amp

In-depth guide to power 2 speakers with a 1 channel amp

Co-authored by Hunter Rising

Last Updated: September 1, 2022

If you have two speakers you want to power from a single-channel amplifier, the first thing you should do is determine the output impedance of the amplifier and the impedance of your speakers. Ideally, the output impedance of the amplifier should match the impedance of the speakers. If you can make the impedances match, you'll be able to successfully use your speakers with the amplifier.

Method 1

Method 1 of 2:

Speakers in Series

1
If you connect the speakers in series, you're adding the speaker impedances together. Example: You have two 4 ohm speakers you want to connect to an amplifier with an output impedance of 8 ohms. For this case, you want to put your speakers in series, so the total impedance of the speakers will be 4+4=8 ohms, matching the amplifier.^{[1]
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2
Plug the negative terminal (-) of the amplifier into the negative terminal of the first speaker.

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3
Connect the positive terminal of the first speaker to the negative terminal of the second speaker.
4
Connect the positive terminal of the second speaker to the positive terminal of the amplifier.

Method 2

Method 2 of 2:

Speakers in Parallel

1
For a parallel connection of two speakers, the resulting impedance is half of the impedance of the amplifier (assuming the speakers have the same impedance). Example: You have the same two speakers, but the amplifier has a 4 ohm output. For this case, you want to connect the speakers in parallel because the impedance would be 8/2=4 ohms, again matching the amplifier.^{[2]
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2
Plug the negative terminal (-) of the amplifier to the negative terminal of speaker 1.
3
Hook the negative of speaker 1 to the negative on speaker 2.
4
Plug the positive terminal (+) of the amplifier to the positive terminal of speaker 1.
5
Hook the positive of speaker 1 to the positive on speaker 2.

Community Q&A

Question

How do I add rear surround speakers to my stereo receiver if it only has connections for 2 speakers?

Community Answer

A stereo receiver will only play stereo (two channels) no matter how many speakers you hook up. You have to have a surround sound system to have rear speakers that actually work properly.
Question

How can I connect 2 8 ohm speakers so they remain 8 ohm?

Community Answer

The best way is to wire them in series, but make sure that you have a powerful enough amplifier to power them, with an output rating of 16 ohms or more.
Question

How do I add subs to a Sony surround system?

Community Answer

Your amp probably has a line level (like a headphone jack) sub output, so you can just buy any active subwoofer and plug it in through that.

Warnings

If the impedance of the speakers is too low, you could damage the amplifier trying to drive them.

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Please consult your amplifier manual for exceptions, variations and warnings, or you may have an expensive lesson.

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