Using DMM to read amp for common ground.

I have very limited knowledge for using a DMM, enough to be dangerous. I have a pair of SDA-CRS monitors. I would like to check my amp to see if it is a common ground amp. I have read you check between the neg speaker posts on the amp. Where do I set the DMM to get the reading & what am I looking for. I have read it several different ways and I am confused. Should I test with the amp powered on or off. Please help.


  • F1nut
    F1nut Posts: 46,494
    Amp off and unplugged. Set the meter to read ohms. Put one lead in the right negative post, the other on the left. If the meter reads zero ohms it's common ground.

    Tip: touch the leads together with the meter on and set to ohms. Note the reading, which may not be exactly zero. For example it could be 0.2. So, when testing the amp if the meter reads 0.2 it's actually zero and the amp is common ground.
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