How to check speaker ohms

George Kimery · Post by **George Kimery** » 6 Mar 2019 9:14 am

I have a cheap multi-tester that has an ohms section. The lowest setting is 200 ohms. I connected it to my 4 ohm JBL-D130 and it read 3.6 ohms. I connected my 8 ohm TT-12 and it checks 5.5 ohms. I know ohms can be approximate when measured. I just need to know if my cheap multi-tester can check ohms by just connecting to the speaker terminals or is a more sophisticated instrument required.

Fred · Post by **Fred** » 6 Mar 2019 9:25 am

Speakers are AC devices so the rating is for AC impedance. The impedance varies with frequency. Your meter reads DC resistance and the readings youâ€™re getting are pretty normal.

Fred

Paul Arntson · Post by **Paul Arntson** » 6 Mar 2019 9:26 am

Sounds like it's working right. The ohm readings measured this way should always read a bit lower than the rating.

George Kimery · Post by **George Kimery** » 6 Mar 2019 10:08 am

I checked with the speakers not connected to an amp. Should they be connected to an amp so they are "hot" when checking?

Paul Arntson · Post by **Paul Arntson** » 6 Mar 2019 10:41 am

Nope. You get better readings when disconnected.
Matter of fact, never try to check ohms on a powered up circuit. Best case the ohm meter will get confused, worst case it will blow it out.

Gary Jones · Post by **Gary Jones** » 6 Mar 2019 12:38 pm

The rule of thumb is to multiply the DC resistance by 1.3

George Kimery · Post by **George Kimery** » 6 Mar 2019 2:00 pm

Gary, are you saying I should multiply the ohms measurements by 1.3 ?

Gary Jones · Post by **Gary Jones** » 6 Mar 2019 4:01 pm

Yes, that is exactly what I'm saying. While DC resistance is not the only component of impedance it is the most significant contribution.
Here is a brief rundown https://www.kevinchant.com/uploads/7/1/ ... edance.pdf .
I hope this helps
Gary Jones
I ain't dead yet.

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