Checking Speaker Impedance With a Multimeter

Here is a video on how to read the impedance of a speaker. If you take a reading of an 8 ohm speaker you will find that it does not read perfectly at 8 ohms. According to Anthony Lucas at Eminence Speakers “When a speaker is labeled 8 ohms, it is actually a nominal reading. An ohm meter measures the resistance to direct current (DC), but music is alternating current (AC). A speaker’s impedance to AC depends on frequency and the nominal rated impedance is sort of an average impedance over the useable frequency range of the speaker”. So do not panic if you wire up a multi-speaker enclosure and it reads below what you think it is going to read. Just observe proper polarity, hook up your speakers and ROCK!!!

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  • Hi Bill, I tested an 8 Ohm and a 4 Ohm speaker impedance with my multimeter and the readings of both where 8.2 and 4.1, I´m not shure if this is correct since you mantion that whe you read the impedance this way you get a lower value.

    Any comment would be appreciated.

    Juan Carlos

  • Hi there Juan Carlos-

    This is strange because any time I have ever read a speaker they always read low. Not all exactly the same but low. Have you tried another meter? Try another meter perhaps. What kind of speakers are they? And are they in 100% working order? Let me know. -Billy

  • Scott Shannon

    The meter measures resistance, not impedance. Impedance actually changes based on the frequency of an AC signal. Speakers are given a rating based on an average impedance over the range of frequencies it will be used. The meter is a useful tool to give you an idea of impedance, but it won’t give you the exact rating.